Overview

The Air Valve element in WaterCAD and WaterGEMS V8i allows users to accurately model the effects of intermediate high points in a water distribution system. This TechNote describes the effect of using air valves at high points in WaterCAD or WaterGEMS V8i and also compares the implementation of the current capability with modeling approaches used in previous versions.

The Trouble with High Points

In the past, high points in a pipeline in WaterGEMS would not be considered for the pump operating point. Basically they would only consider the boundary conditions (reservoirs and tank elevations) in your system. So, the pump will add enough head to lift the water to the downstream known hydraulic grade. It does not consider junction elevations inbetween and simply calculates a pressure at the junction locations based on the difference between the hydraulic grade and the physical elevation. So, this sometimes resulted in a negative pressure being calculated in the vicinity of the high point. This situation can be seen in the profile below, in which the hydraulic grate line (in red) is lower than the pipe elevation (in green) at the high points.

This approach basically simulated the effect of water being siphoned over the high point, which is usually not the case in real systems, since most utilities place air release vacuum breaker valves at the high points, and since the vapor pressure of water limits the height of a potential siphon. Since neither of these factors was accounted for in most pressure pipe models, including older versions of WaterCAD and WaterGEMS, the results typically overestimated pump flow and underestimated head (i.e., the pump ran too far to the right on its curve). Basically the head added by the pump was lower than what would really be necessary to 'lift' the water to the high point

In earlier versions of WaterCAD and WaterGEMS (V8 XM and below), it was difficult to implement a workaround to this problem. Some possible solutions included placing a small tank at the high point, controling flow with a FCV (flow control valve) or using a PSV (pressure sustaining valve) to set the pressure to zero. In many cases, the modeler would simply ignore the negative pressure and accept the pump operating point.

However, even with a workaround, modelers sometimes found that the high point may be pressurized for higher flows, as shown below. This situation could prove especially problematic in the case of an extended period simulation demonstrating both flow regimes.

The Air Valve Solution

WaterCAD and WaterGEMS V8i provide an answer by incorporating a new air valve element. By placing an air valve at the high point, the pump sees the air valve elevation as its downstream boundary condition for instances in which pressure would have otherwise been negative at the high point:

Note: The Air Valve element was actually added to WaterCAD and WaterGEMS in the V8 XM release, with version number 08.09.400.34. However, the air valve in this version did not include the special behavior described in this technote; it always acts as a junction during the EPS or steady state simulation. It only operates during a transient simulation, when opening the model in Bentley HAMMER.

For instances in which the pipeline functions under pressure/full flow for its entire length (e.g., during the high-flow condition), the pump operating point is correctly based on the downstream boundary condition, similar to the behavior in older versions.

When the air valve is open, the hydraulic grade on the downstream side may be less than the pipe elevation. This can be displayed as the hydraulic grade line drawn below the pipe. This should be interpreted as a pressure pipe that is not flowing full. Full flow resumes at the point where the hydraulic grade line crosses back above the pipe. To accurately observe this phenomenon in a profile, you should ensure that the elevation of the junction immediately downstream of the air valve is above the point where full flow resumes. For example if your next-downstream junction is far away and at a low elevation, you may not observe the part-full phenomenon. This is because WaterCAD/WaterGEMS can only report/compute hydraulic grade at nodes, so it can only draw the HGL between them.

Troubleshooting

Because air valves have the possibility to switch status, they can lead to instability in the model especially if there are many air valves in the system. To improve the stability of the model, it is desirable to force some of the valves closed. This can be done by setting the property "Treat air valve as junction?" to True for those valves that are expected to be closed anyway.

For any air valve that you expect to be open and that should behave as described in this technote, ensure that you choose "false" for the "Treat air valve as junction?" attribute.

If all of the pumps upstream of an air valve are off, the pressure network is disconnected in that area and the model will issue warning messages for all nodes in that vicinity indicating that they are disconnected.

In addition, the profile between the air valve and the pumps that are Off will be inaccurate. To make the profile view accurate, you can place an imaginary tank or reservoir on a short branch with a tiny diameter pipe at an Elevation (Initial) equal to the air valve elevation. This tank (which will not contribute significant flow) can eliminate the disconnected system message and correctly represent the fluid in the upstream pipe when the pump is off

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs 

WaterGEMS V8 Modeling FAQ 

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Water and Wastewater Forum

Overview

This video demonstrates how to open older WaterCAD or WaterGEMS models in V8 XM or V8i.

Support Video Clip

(Recorded in 1024 x 768 resolution.  Right-click for playback options.) 

[View:http://communities.bentley.com/cfs-filesystemfile.ashx/__key/CommunityServer-Components-PostAttachments/00-00-13-62-75/FileConversion.wmv:640:480]

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

This tech note should help you understand how the Projectwise integration works and what you need to do in order to integrate Projectwise with WaterGEMS v8i. 

What is Projectwise?

ProjectWise is a suite of software from Bentley Systems aimed at helping manage, find, and share CAD and geospatial content, project data, and documents.

What’s new in ProjectWise?

ü    Captive Environment

ü      Spatial Reference System (SRS)

ü      Single Sign-on and Auto-login support

ü      Document creation wizards

ProjectWise integration must be enabled before WaterGEMS V8i can directly interact with ProjectWise

How to enable Projectwise?

Browse to C:\Documents and Settings\All Users\Application Data\Bentley\WaterGEMS\8\  and open ProjectWiseIntegrationLocalOptions.xml in text editor. (In Windows7 or vista, the file will be at  C:\ProgramData\Bentley\WaterGEMS\8 directory.)

Find the line that sets the PWDIR variable  PWDIR=""  and change it so that it refers to the directory where a supported version of the ProjectWise Explorer is installed, such as PWDIR="C:\Program Files\Bentley\ProjectWise\"

For the MicroStation platform, you must enable the ProjectWise iDesktop integration for Microstation when installing the ProjectWise Explorer client software. You can also Change the ProjectWise Explorer installation to enable this from the Windows Control Panel.

The ArcGIS platform will automatically detect an installed ProjectWise Explorer.

The AutoCAD platform does not currently support ProjectWise integration

What is Captive Environment?

The term captive environment refers to the state of integration when the user cannot save documents to or open documents from the local file system.  They are “captive” or forced to work in the ProjectWise environment.

Captive Environment Setup for Users

 Open ProjectWiseIntegrationLocalOptions.xml in text editor.  It’s the same file we used for Watergems integration with Projectwise.

Locate the following string below on this text file and change UseCaptiveEnvironment =“true” and save it

<ProjectWiseIntegrationLocalOptions

 PWDIR="C:\Program Files\Bentley\ProjectWise"

 UseCaptiveEnvironment=“false"/>

*** Make sure to close out of Projectwise and WaterGEMS to see this change

Captive Environment Setup for Administrators

Open ProjectWiseIntegrationLocalOptions.xml in text editor.  It’s the same file we used for Watergems integration with Projectwise and it is located on your local drive C:\Program Files\Bentley\ProjectWise\ProjectWiseIntegrationLocalOptions.xml

Locate the following string below on this text file and change UseCaptiveEnvironment =“true” and save it

 <ProjectWiseIntegrationLocalOptions

 PWDIR="C:\Program Files\Bentley\ProjectWise"

 UseCaptiveEnvironment=“false"/>

*** Make sure to close out of Projectwise and WaterGEMS to see this change

Spatial Reference System (SRS)

 •       The SRS is a standard textual name for a coordinate system or a projection, designated by various national and international standards bodies

•       The primary use of the project's SRS is to create correct spatial locations when a managing a project in the ProjectWise Integration Server's spatial management system.

•       The SRS name comes from the internal list of spatial reference systems that ProjectWise Spatial maintains on the ProjectWise server and is also known as the "key name." To determine the SRS key name, the administrator should browse the coordinate system dictionary in the ProjectWise administrator tool (under the Coordinate Systems node of the datasource), and add the desired coordinate system to the datasource. For example, the key name for an SRS for latitude/longitude is LL84, and the key name for the Maryland State Plane NAD 83 Feet SRS is MD83F. 

Single Sign-on and Auto-login support

·         Single Windows login allow you to login each time you open Microstation or any other platform

·         Auto-login gives you option to remember the datasource next time you log into this application

Document creation wizards

• No Wizard icon — Selecting No Wizard icon and clicking Set as Default means that the standard document creation dialog will open instead of the Advanced Document Creation Wizard. So when No Wizard is set, the Create Document dialog opens when you select Document > New > Document, and the Copy Document dialog opens when you select Document > Copy To. Also, clicking OK in the Create Multiple dialog will automatically create the specified number of documents (with no files attached), and copying or moving documents in ProjectWise Explorer using the drag and drop method will automatically perform the copy or move.

Selecting No Wizard here also ensures that if you attempt to create a new document in an integrated application, the application will open whatever ProjectWise dialog it normally uses to create new ProjectWise documents.

• Advanced Wizard icon — Selecting Advanced Wizard and clicking Set as Default means that the Advanced Document Creation Wizard will be used when creating documents. (The Advanced Document Creation Wizard Properties dialog controls which document creation actions will invoke the Advanced Document Creation Wizard.)

Selecting Advanced Wizard here also ensures that if you attempt to create a new document in an integrated application, the application will open the Advanced Document Creation Wizard.

• Clear Default / Set as Default — Clicking the Clear Default button signifies that you do not want to commit to a default document creation method. When you click Clear Default and the --no default wizard-- message appears in the dialog, this means that the Select a Wizard dialog will open whenever you select Document > New > Document, whenever you create multiple documents using the Create Multiple dialog, and whenever you copy or move documents using the drag and drop method. Clicking the Set as Default button sets whatever method (icon) you select from the list as the default method for creating documents.

Setting --no default wizard-- here also ensures that if you attempt to create a new document in an integrated application, the application will open the Select a Wizard dialog.

• About — When the Advanced Wizard icon is selected, clicking the About button opens an information box that provides — information — about the benefits of the Advanced Document Creation Wizard.

• Properties — Opens the Advanced Document Creation Wizard Properties dialog, which is used to specify which document creation actions will invoke the Advanced Document Creation Wizard, and which pages on the wizard will be hidden from the user.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please confine any comments you have on this Wiki entry to this "Comments or Corrections?" section. THANK YOU!

Overview

This Technote describes the process by which a user can export their model to an i-model file. It assumes Bentley WaterCAD, WaterGEMS or HAMMER V8i (SelectSeries 3). 

When installing WaterCAD/GEMS or HAMMER, the i-model publishing engine shows as a dependency on the download page. 

What is an i-model?

How to Publish an i-model

In WaterCAD/GEMS or HAMMER
 - First, you will want to select the desired scenario and time-step.

 - File > Export > Publish i-model

The following dialog opens with the defaults set so that all elements and properties are included in the i-model.

 - The top left pane is a summary of the element types to be included in the i-model.  If a box by the element type is checked, that element type is included.  The Table/Properties column reflects the selections on the right side of the dialog in terms of which elements and properties are to be included.

 - The bottom left portion of the dialog box is used to identify which elements are to be included in the i-model.

 - If the "Publish a subset of elements based on the Flex Table filters" box is checked, only those elements that are in the filtered flex table will be included in the i-model.

 - If the "Exclude topologically inactive elements" box is checked, only active elements (Is Active? = True) are included in the i-model.

 - The user will usually not need to include all element properties in the i-model.  The right side of the dialog is to identify which properties of the elements are going to be included in the i-model.  The default is "all properties".  If the user wants to only include a subset of peoperties, the user should create a flex table with only those properties and select that flex table from the drop down list.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]  

External Links

Water and Wastewater Forums

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

This technote will explore the new pump station element and pump combination curves feature to provide a better understanding of how they are used and what they can do.

Pump Station Element

The new pump station element provides users a way to indicate pumps which are located in the same structure, serving the same pressure zone.  

• The element can be accessed by clicking on this icon in the layout toolbar    
• It doesn't contain any data fields that require data input

• It has polygon geometry on the drawing pane

How to layout a pump station

1. Select the pump station icon from the layout toolbar
2. On the drawing pane, left click once to set the first point for your polygon
3. Move your cursor to the next position and you should notice a line being drawn
4. Repeat steps 2 and 3 until you have laid out your polygon
5. When you get to the last node and want to finish or close the polygon, right click the mouse button and select 'Done'.

How it works

In order to associate pumps to the pump station element, you must go into the properties of each pump that you want to associate to the station and change the field labeled "Pump Station". When you click the field you will have the option to 'select' the actual pump station polygon by clicking on it or choosing the pump station from the drop down menu. See the red box in the screenshot below.  

 In order to identify the association of a pump with a pump station in your model, you will look for a dotted line connecting the pump to the pump station. This can be seen in the screenshot below. 

Combination Pump Curves

This feature allows for multiple pump curves, efficiency curves, wire-to-water efficiency curves(overall efficiency curve), and system head curves to all be displayed on a single graph.

The combination pump curve feature can be accessed in two ways.

1. Right clicking on the pump station element. After right clicking, a context menu will come up and you can select 'Combination Pump Curves'. 
2. Go to Analysis > Combination Pump Curve. This opens the combination pump curve manager. From here you would click the 'new' icon, which looks like a white piece of paper, and then double click the new pump combination curve.

Both options above result in the following window opening:

 In the screenshot  below, I have divided the combination pump curves window into 4 sections for discussion purposes.

 Section1

As you can see in the screenshot above, this section displays the active pump station and shows all the pump configurations that are possible. If you would like to change the pump station you are currently viewing, you would click on the ellipsis button next to the pump station pull down and then select another pump station.

What do the columns mean?

Section 2

In the screenshot above, we can see on the left is where you would select which curve(s) you wanted to display in the graph. You would select the ones you wanted by checking the box next to them.

The four choices are:

1. Head Curve
2. Efficiency Curve
3. Wire-to-Water Efficiency Curve (Overall Efficiency)

4. System Head Curve

NOTE: You do not need to run your model to be able to generate a head, efficiency, or wire-to-water efficiency curve. If you would like to generate a system head curve however, you will need to run/compute your model.

On the right side of this section you see the "Time (hours)" list. This list only becomes available to use when the system head curve box is checked. Here you would select the time you want to see the system head curve displayed for and at least one time has to be checked to plot a system head curve. 

The first three choices for curve display are simple because all you do is check the box next to them. The system head curve however, involves some more information to be provided. When this box is checked, the user must specify the 'representative pump'. This is the path through the station that the head loss is calculated from and the results from the pump you select usually don't vary that significantly from the other pumps. You can also see the options to specify a 'Maximum Flow' and 'Number of Intervals'.  Maximum Flow will determine the horizontal extent of the system head curve and the number of intervals will specify the number of points along the curve that will be calculated.

Section 3

This section is small, but critical to using the Combination Pump Curves feature. It consists of the compute button and the chart options button. As can be seen above, clicking the chart options button will bring up the chart options settings. Here you can change just about anything you can think of for your graph display. The compute button is what ties the changes that you make by selecting to display one or multiple curves to the graph area. You will need to click the compute button after you make any of the following changes:

1. If you want to add/remove a pump combination using the  'Is Active?' check box
2. If you want add/remove a type of curve (i.e. head curve, efficiency curve, system curve, wire-to-water-efficiency curve)

3. If you want to add/remove a time from the system head curve

Section 4

The final section, as seen in the screenshot above, is the graphical display. The 5 main parts are the title of the graph, the X and Y axes, the graphing area, and the legend. Most of the options for these parts of the display can be changed or adjusted using the chart options icon from section 3. The legend is associated with the ID's found in section 1. (i.e. Head |X|, where  X = some number, is referring to the ID given to each pump combination curve as see in section 1)

Solving Combination Pump Curves

 Identical Pumps

• When pumps run in parallel, they all have the same value for head (unless adjacent pipe headloss is significant.)

• For each head where the flow is > 0, flows from each pump are additive (e.g. A pump station with 3 pumps that have a head of 100 ft. Pump 1, 2, and 3 produce flows of 50 gpm, 50 gpm, and 60 gpm, respectively. The flow from the 3 pumps will therefore be 160 gpm. The coordinate for the point on the combined pump curve would be (160, 100))

• Will have 'n' number of combinations where 'n' is the number of pumps in the pump station. (e.g. If you have 3 pumps then you have 3 combinations)

 Non-Identical Pumps

• The number of combinations is based on the number of pump curves that you have (e.g. 2 pumps with type A curves, 2 pumps with type B curves, 2 pumps with type C curves)

There are a total of 24 possible combinations as can be seen in the table below.

Why doesn't the sum of the pump flows match the intersection of the system head curve?

When computing a model with multiple pumps in parallel, in some situations you may notice that the sum of the pump flows do not match the operating point of that particular combination, in the pump combination tool. This is expected behavior for a pump station in which the head loss through each pump is different.

When generating a combination pump curve, the system head curve is based on one single representative pump. This means that the system head curve will reflect the head necessary to overcome head losses through the selected pump. In most cases, the head losses through each pump in series will be similar, so the selection of representative pump would not make a difference. Meaning, if the headloss through each individual pump is the same, the system head curve will represent the system head curve of the entire station.

However, if the head loss through one particular pump is significantly greater than other pumps in the station, it could have a relatively large effect on the system head curve. Because of this, when the pumps are all turned on, their operating points will be different, since the one(s) with higher head losses will need to add more head. Because of this, there really isn't a single operating point for the pump station in this situation, but instead a separate operating point for each one. Therefore in these cases, the intersection between the system head curve and combined pump curve is not the operating point of the station. So, you would not be able to simply add up all the flows and compare to the operating point. In these cases, the representative system head curve can be viewed as an approximation.

Furthermore, if you are comparing the operating point in the Combination Pump Curve tool to the sum of the flows from multiple pumps in the station being turned on, they may not match if there is A) significant headloss between the pumps and the common downstream node or B) no common downstream node (each pump having its own parallel pipe going all the way down the system). The key is that the flows on the system head curve in the combination pump curve tool are forced through the specified "representative pump", as opposed to being evenly dispersed among those pumps. For instance if you have five pumps running in the model, the flow may be 1000 gpm X 5 = 5000 GPM, yet if you look at the combination pump curve for those five pumps together, the system head curve might intersect at something lower such as 4000 gpm. The reason is because that entire 3000 gpm is forced through that single pump, so if the piping just downstream is undersized, you can end up with more headloss compared to the same flow dispersed among the five pumps. So again, in these cases the system head curve can be viewed as an approximation.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

The purpose of this technote is to discuss the Criticality feature available in the Bentley WaterGEMS and WaterCAD. Additional information can be found in the Help menu for the products. There is also a Quick Start Lesson available for Criticality until Help > Quick Start Lessons.

Background

Bentley WaterGEMS V8i provides the user with a flexible tool to evaluate and identify the most critical elements in a water distribution system. Using this process, the user can shut down individual segments of the system and view the results on system performance. This is simulated in a single run rather than in a series of different scenarios.

A variety of indicators is reported for each outage during the criticality analysis. Depending on the type of run, criticality analysis can report the flow shortfall, volume shortfall or pressure shortfall in the distribution system for each segment outage.

Getting Started

Before conducting a criticality analysis, the segments to be removed from service during the analysis must be identified. Often this will be defined by the valves in the system, wherein a closed valve will disrupt service to parts of the model. Included in this, the user must identify which types of valves will be used in the analysis. The user will also have to decide which scenario will be used for the analysis.

Once identified, this information will be entered into the Criticality manager. The steps to do this and compute the criticality analysis are detailed below.

Running a Criticality Analysis

Segmentation Analysis:

The Criticality manager can be opened by going to Analysis > Criticality, or by clicking the Criticality icon in the toolbar.

This will open the following dialog:

Next, click the Options tab. In this section, you will identify how the segments in the analysis will be defined.

The recommended procedure is to place isolation valves on the pipe elements. If you don’t have sufficient data on the location of isolating valves, each pipe element can be isolated. In this case, each distribution segment consists of a single pipe, not including the nodes at each end. You can set this up by way of the “Consider Valves?” option at the top of the page. By default, this item is checked. When it is checked, the segments are defined by the valves. If it is unchecked, the pipes are isolated individually.

When the “Consider Valves?” option is selected, the default status of the valves is available. By default, these will be set to “Always Use.” If you have some valve types that you don’t want used in the criticality analysis, change this field to “Do Not Use.” Note: if you don’t have a given valve type in the model, you can leave this with the default setting.

There is a valve override section at the bottom of the page. This item is used in cases where an individual valve will not be considered in the analysis, such as if the valve is broken open. Once the options are set as needed, click the New icon in the upper left and choose the scenario you will be using in the analysis. Once this is done, you will have to select the segmentation scope of the analysis. You can either choose a subset of the model or the entire network. With Subset is selected, you can select the subset by clicking the ellipsis button. If you choose Entire Network, all elements in the model will be used.

Next, click the green Compute icon. You may be prompted about update valve placement data. Typically, you will click Yes for this. The criticality analysis will then run. The results will be available in the Segmentation Results tab.

In the middle pane will be a list of all of the segments. In the right pane, you will see the distribution of segments and their properties, such as the number of pipes in a segment and the number of affected nodes. The displayed results are governed by the highlight segment in the middle pane.

Note: this is true of viewing results for the Outage Segments and Criticality sections below as well.

You can view the segments graphically by clicking the Highlight Segments icon at the top of the middle pane.

If you minimize Criticality manger, you can then view the segments on the model itself.

Analyzing Outage Segments:

Once the segmentation is completed, you then do an outage analysis. This allows you to determine which segments are affected when a certain valve is closed. To do this, highlight “Outage Segment” in the left pane and select the green Compute icon.  

The results from this section will show you how an outage affects a model, including the number of affected elements. You can also view these outage segments graphically in the model. Highlight one of the outage segments in the middle pane and select the Highlight Segment icon. When you minimize the window, the outage segment chosen will be highlighted.

Criticality Analysis:

The final step is to see how the outages affect the demand. This is the most important function of the criticality analysis. It will determine if the system can supply the needed demand if a section is closed, and if it cannot, how much demand is not supplied as a result of the closure.

Highlight “Criticality” in the left pane. At the top of the right pane is an item called “Run Hydraulic Engine?” If this is unchecked, the model will check the connectivity of the model with certain segments are closed. If you select the green Compute icon, you will be able sort the results to see which outage segments will cause the largest disruption by looking at the “System Demand Shortfall” column.

If you place a check in the “Run Hydraulic Engine?” icon, the program will hydraulically compute the model as well. If the demands are not met in that segment, the check box in the column “Are all demands met?” will not be checked.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]  

External Links

Water and Wastewater Forums

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

 Overview

This TechNote explains the steps needed to perform a Pipe Break Analysis in WaterGEMS and WaterCAD V8i.

Background

Bentley WaterGEMS/WaterCAD V8i provides a very useful tool to analyze pipe breakage over time and also calculates a projected pipe break rate and auxiliary costs based on historical pipe break data.  It is important to note that WaterCAD/GEMS computes and displays the results based on the data entered by the user, and it does not come up with the pipe break history. Hence, it is important to accurately enter this data. The results of pipe break analysis are useful in themselves but they also serve as one of the inputs to Pipe Renewal Planner.

Before You Begin

You will need:
1) The WaterCAD\WaterGEMS model
2) Pipe break history data, which can be entered directly in WaterGEMS/WaterCAD or imported from an external source file (i.e. Excel spreadsheet), which can be in either of these two formats:

·         A table with one record per pipe consisting of pipe ID in one column and the number of breaks in another column (Pipe Break Table)

·         A table with one record per pipe break (failure) with the pipe ID serving as one of the fields in each record (Failure History)

3) Define Pipe Break Groups by creating selection sets of pipes that share similar properties with respect to pipe breakage. These properties would include similar age, material, laying condition and loading and period of break records. Pipe Break Groups can be modified or created by selecting Components > Pipe Break Groups.

Note: It is usually best to create selection sets of such pipes before starting the pipe break analysis. Name the group with a label that reflects the pipes in the group. If a pipe is not assigned to a group, its individual break rate will be used as the scaled break rate.

Setting Up Scenario with Pipe Break Alternative

Create a scenario to use with the Pipe Break Analysis, or use existing scenario if you wish.  Make sure to set the scenario with the Pipe Break Alternative as current. (See TechNote on Scenario and Alternatives if you need help setting them up).

The alternative associated with the Pipe Break Analysis is “Failure History”. 

1)     Go to Components > Alternatives

2)     Expand the Failure History alternative then double-click on Base Failure History

3)     Enter the “Duration of Pipe Failure History” value on top.  If it is different for several pipes, check the “Use Local Duration of Pipe History” field, then you can enter the correct value for each pipe in the Duration of Pipe History column.

4)     Data for the pipe break analysis can be entered in the alternative window, or it can be entered in the Pipe Break Analysis window (see below).

Start Pipe Break analysis

Go to Analysis > Pipe Break, or click on the Pipe Break icon on the toolbar:

1)     In the wizard, click on New

2)     Select the scenario from the drop-down list in which you want to perform the pipe break analysis

3)     Now, to bring in the pipe break history, you can either enter it manually in the table, or use the Import button to bring it from a data source file (i.e. Excel spreadsheet, Access, etc). To import data from a file, click on the Import button

4)     In the Import wizard screen, select the data source type and browse to the location of the file. Click on Next.

5)     Confirm the scenario in which this data will be imported, and the key field to be used. Click on Next.

6)     On this screen, you will map the fields in the data source file with the fields in the model.  Choose the Key Field, which is likely to be Label.

Note: You can also use the import wizard to bring in Pipe Break Group data, but in order to do that, the Pipe Break Groups have to be defined first (which will be discussed later on).

7)     Click on Finish. If prompted, click on Yes to synchronize the drawing.

8)     Close out of ModelBuilder Summary. Review imported data in the table.

Pipe Break Group

To assign pipes to pipe break groups, you can do by either:

a)     Assign pipes of different groups to different selection sets

b)     Create Pipe Break Groups and then use the import feature to bring in the data from a data source file (i.e. Excel spreadsheet).

c)     Add pipes from the drawing manually to Pipe Break Groups

a.  Creating Selection Sets for each Pipe Break Group

First create selection sets of pipes for each one of the different pipe break groups.

1)     Open the Pipe Break Analysis

2)     Click on the Pipe Break Group tab to setup the pipe break groups.

3)     Click on the Pipe Break Group button

4)     Click on the New button in the next window.

5)     Click on the “Add Pipes from Selection Set” icon

6)     Then choose the selection set to bring in.

7)     Repeat the steps above to bring in all other pipe break groups.

b.  Create Pipe Break Groups, then Import Pipe Break Group data

If you have the pipe break groups listed in a data source, then you can use the steps below to assign them in your model. It can look like this for the Pipe Break Table:

or this, if it is a Failure History (note how each pipe is listed once for each break record):

1)     Open the Pipe Break Analysis

2)     Click on the Pipe Break Group tab to setup the pipe break groups.

3)     Click on the Pipe Break Group button

4)     Click on the New button in the next window.

5)     Create the pipe break groups for your model and rename them to match the name in the data source file. 

6)     Enter the “Duration of Pipe Group Failure History” for each group you created

7)     Next, click on Close. Then go to the Pipe Break tab, and click on the import button.

8)     Follow the steps above to map the fields in the data source with the Pipe Break Group (label) in the model. Note: make sure to select the correct table format for your data source (if Failure History is selected, the "Number of Breaks" field will not be available).

9)     Click on Finish.

10)  Now click on the Pipe Break Group tab, then click on the Pipe Break Group button.  The pipes should now be listed under its associated group. Click on Close.

Setting Analysis Options

1)     Click on the Options tab

2)     Under “Break Rate Scale”, move the scale to select the extent to which the overall scaled pipe break rate for the pipe is based on the individual pipe's history (a value near 1) or the group's history (a value near 0). Moving the slider to the left, lowers the value 'a' in the following equation, and increases the importance of the group while moving it to the right increases 'a' and decreases the importance of the group.

     Projected break rate = a (Individual break rate) + (1- a) (Group break rate)

3)     Check the “Compute Pipe Break Auxiliary Results” box if you want to display projected number of breaks and their break costs. Enter the Projection Period and Interest Rate to be used in projecting breaks and cost.

Run the Analysis

1)     Click on the Compute button

2)     Review the results under the Pipe Break tab

The results that are calculated by the Pipe Break Analysis include:

·         Break rate (breaks/yr/mi) - based on length and number of breaks for individual pipe over the duration of break history for that pipe

·         Break rate (Pipe Group) (breaks/yr/mi) - based on the number of breaks and total length of pipe in the group that this pipe belongs to over the duration assigned in the pipe group dialog.

·         Break Rate (Scaled) (breaks/yr/mi) - based on the weighted sum of the individual pipe break rate and the break rate for the group that the pipe belongs.

·         Projected breaks - the product of the scaled break rate, the projection period and the length of pipe. Estimate of the number of breaks over the projection period assuming that past break rates persist.

·         Annual cost - the product of the scaled break rate, the length of pipe and the cost per break. Estimate of the annual cost of breaks.

·         Present worth - the product of the scaled break rate, the length of pipe and the cost per break multiplied by the series present worth factor. Estimate of the present worth of all break costs over the projection period.

The results can also be color coded under the Element Symbology, to display the number of breaks, break rate, or any of the other calculated fields:

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

General WaterGEMS V8 FAQ 

External Links

Water and Wastewater Forums

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

SCADAConnect - Citect

One of the methods to bring SCADA data into a hydraulic model via SCADAConnect is by using a Citect Connection directly. To establish the connection and to import the data, there are a few specific steps in the Connection Manager and Data Source Manager of SCADAConnect.

Connection Manager (for Citect)

Information that needs to be entered in the Connection Manager will be different based on the location of the Citect Server hence the Connection Manager needs to be configured accordingly.

1)    Within SCADAConnect, go to Tools > Connection Manager.
2)    The Connection Manager opens.
3)    Click the New button and select Citect.
4)    The Connection Manager screen will change as below.

Note

Citect SCADA is not supported on 64 bit architecture so the following message may show up when clicking on Citect in the Connection Manager.  You will need to open the 32 bit version of WaterGEMS/WaterCAD directly (from installed directory typically, \Program Files (x86)\Bentley\WaterGEMS (or WaterCAD).




Remote Server

In a condition where the Citect Server is located on the same machine where the hydraulic modeling software is installed, there is no need to enter the server name. So, leave the Server name field blank. However, the server name is required when the Citect Server is on some remote machine. So, put a check mark on Remote Server and enter the Server name. Typically, the server name is the same as the computer name of the remote computer.

Only for Remote Citect Server (Not Required for Local Citect)

If the Citect server is on a remote machine then certain information needs to be updated on the server side so that a remote computer can communicate with it. The following change is for Citect version 7.20. Any version lower than this, may not require the change.

1)    From Start > Programs > Citect > CitectSCADA 7.20 > Runtime Configuration
2)    Click on Computer Setup Editor.



The following window will open



In this window, either create or update the CtAPI node and make sure it has the sub-items as shown.

CtAPI
     AllowLegacyConnections = 1
     Remote = 1

Save the settings file (File > Save on Computer Setup Editor) and exit out of the Computer Setup Editor window.

Authentication

Enter the User Name and Password used in the Citect Server in the Connection Manager window. (To add/edit users in Citect 7.20, Open Citect Explorer > My Projects > Project Name > System > Users)

Test Connection

After entering the server name (for remote Citect), User Name and Password, click on Test Connection. If you receive “Connection Unavailable”, follow the Citect Connection Troubleshooting steps. If everything is ok, a “Scada connection succeeded” message will be displayed.

Click OK on the Connection Manager to exit out of this window.

Data Source Manager (for Citect Source)

There is not a lot of change or user input needed in the Data Source Manager with a Citect Source. To create a new item for a Citect source, click on the New button dropdown, select New Citect Data Source and update the field as shown:

1)    Connection:  Select the connection created in the Connection Manager step from the dropdown.
2)    Table Name: TAG
3)    Name: NAME
4)    Value: VALUE
5)    Time Stamp: DATETIME

Click OK to exit out of the Data Source Manager.

The rest of the SCADAConnect related methods are the same as of the regular/database connection option. So, follow the instruction as described in the Help document.

Citect Connection Troubleshooting

 1)    Make sure the 32 bit version of the hydraulic modeling software (WaterGEMS/WaterCAD) is running. To check, go to Help menu > About and look at the lower left corner.



2)    Make sure the necessary Citect dll files are copied to the correct location. On a 64 bit computer with WaterGEMS, it would typically be, C:\Program Files (x86)\Bentley\WaterGEMS\. The necessary dlls can be copied from the Citect installed directory, typically
C:\Program Files (x86)\Citect\CitectSCADA 7.20\Bin\ .The files to copy are:

CiDebugHelp.dll
Ct_ipc.dll
CtApi.dll
CtEng32.dll
Ctg32.dll
CtRes32.DLL
CtUtil32.dll

Should there be any difficulty finding these files, please contact Bentley Technical Support team.

3)    Make sure the Remote Citect (if connecting to a remote Citect Server) is reachable from the client machine. This can be done using the ‘ping remoteComputerNameHere’ command on the command prompt.

4)    Make sure the User name and Password combination is valid.

5)    Make sure Advance Logging is enabled and look at the log file. Calling Bentley Technical Support might be a good option at this step.

6)    Make sure that the latest patch has been applied. To download the latest patch, contact your local IT support, download from the website http://appsnet.bentley.com/myselectcd/default.aspx  or contact Bentley Technical Support team.

See Also

Product TechNotes and FAQs

Water and Wastewater Forum

Haestad Methods Product Tech Notes And FAQs

External Links

Bentley homepage

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Background

This technote is meant to help with confusion about how modelbuilder can be used to set boolean fields.

Setting Boolean (True/False) fields using Modelbuilder 

There are a few different ways these fields can be set using modelbuilder. The setting somewhat depends upon whether you are updating a model or if the you are creating a new model.

Creating a New Model

If you are creating a new model you will be using an excel spreadsheet, shapefile(s), DXF(s), or some other data source to tell modelbuilder how to build your model. There are 2 ways that work well if you need to set a boolean field during your modelbuilder run. Both need to be performed before you run modelbuilder. 

    1)   Adding a column with 0's and 1's

    I.   Add an integer column to your data source that contains either 0's for False or 1's for True. See screenshot below for an example.

    II.   When you get to the object mapping step of the modelbuilder wizard, map this field to the boolean field in the   program. (e.g. The field in your data source that contains the binary values is called Tru_Fals. You would map this field to the boolean field you want to set.) In the screenshot below, Tru_Fals is mapped to "Has User Defined Length?".

     III.   If the setting boolean field will expose or makes another field active, as in the example above, map sure to map it too.

NOTE: If you aren't sure if another field will be exposed or made active the best way to find out is to open a model and change the properties of that field in the specific element for which it is applicable. 

    2)   Creating a prototype

    I.    By creating a prototype, you can configure the default values for any new element that is created from that point forward. Prototypes can be accessed from "View" off the main menu bar.

NOTE: If you are not familiar with how to set up a prototype, the included Help documentation provides a good explanation. You can find this specific help document for prototypes by doing a search for the help document titled "Using Prototypes". If the search option in Help is not exposed you should click the first icon at the top of the help page which should say "Show".

    II.   Once a prototype has been created you can then run modelbuilder without having to worry about setting the boolean fields. However, if some elements should be true (checked) and others false (unchecked), you will need to use method #1 described further above.

Updating an Existing Model

If you are just updating elements in a model that already exist with modelbuilder, the best way that I have found to set the boolean fields is by doing a global edit on the element's flextable. There are two situations which you may encounter if you are updating an existing model: 1) Updating all elements 2) Updating just selected elements

    1) Updating all elements

     I.   Open the flextable for the element who's boolean value field you want to set.

    II.   If the field that you want to edit is not already in the flextable, add it to the actively displayed fields using the 'Edit' icon    located at the top of the flextable.

    III.   Once the field is added, right click on the boolean column and select 'global edit' from the context menu. Set the field to either true or false.

    IV.   Run modelbuilder

    2) Updating selected elements

    I.   Select only the elements that you want to change the boolean field for by using one of the selection methods such as, point and click, building a query, or selection by polygon. 

    II.   Once the elements are selected, create a selection set by right clicking in the drawing pane and selecting 'Create Selection Set' from the context menu.

    III.   With the elements still selected (highlighted) in the drawing pane go to 'View'  from the main menu toolbar and pick flextables {or hold CTRL + 7}. This should open the flextable manager window. In this window right click on the flextable that you are going to be setting the boolean field for and select  'Open on Selection'. This should open the flextable with only the elements that you have highlighted in the drawing pane shown.

    IV.   Follow steps I - IV above under 'Updating all elements'. 

See Also

Building a Model Using Model Builder

Updating a Model Using Model Builder

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

Fire flow analysis is a common tool used in WaterCAD and WaterGEMS to ensure adequate protection is provided during fire emergencies. There are two types of fire flow analysis available to the user: manual and automated. This article concerns how automated fire flows are set up and how to interpret the results.

Setup of automated fire flow analysis

1. In WaterCAD/WaterGEMS select the Analysis pull-down menu, then Alternatives.
    
2. In the Alternatives dialog box, select the Fire Flow alternative, then click Edit.
   
3. Specify values for the Needed Fire Flow, the Fire Flow Upper Limit, Apply Fire Flows By, Residual Pressure, Minimum Zone Pressure, and specify any Selection Set being used.
   • Needed Fire Flow - Flow rate required at a fire flow junction to satisfy demands.
   • Fire Flow Upper Limit - Maximum allowable fire flow that can occur at a withdrawal location. It will prevent the software from computing unrealistically high fire flows at locations such as primary system mains, which have large diameters and high service pressures.
   • Apply Fire Flows By - There are two methods for applying fire flow demands. The fire flow demand can be added to the junction's baseline demand, or it can completely replace the junction's baseline demand. The junction's baseline demand is defined by the Demand Alternative selected for use in the Scenario along with the fire flow alternative.
   • Residual Pressure - Minimum residual pressure to occur at the junction node. The program determines the amount of fire flow available such that the residual pressure at the junction node does not fall below this target pressure.
   • Minimum Zone Pressure - Minimum pressure to occur at all junction nodes within a zone. The model determines the available fire flow while assuring that the minimum zone pressures do not fall below this target pressure. Each junction has a zone associated with it, which can be located in the junction's input data. If you do not want a junction node to be analyzed as part of another junction node's fire flow analysis, move it to another zone.
   • Use Minimum System Pressure Constraint - Check this box if a minimum pressure is to be maintained throughout the entire pipe system.
   • Minimum System Pressure - You can specify a minimum pressure allowed at any junction in the entire system as a result of the fire flow withdrawal. If the pressure at a node anywhere in the system falls below this constraint while withdrawing fire flow, fire flow will not be satisfied.
4. Specify any Local Fire Flow Constraints for the system junctions.
5. Click Close, then click Close in the Alternatives dialog box.
6. Click GO on the main toolbar pallet on the drawing pane, place a check in the Fire Flow Analysis box, then click GO.
   
7. View Results in Results tab. The Fire Flow Results folder will inform you whether the fire flow constraints were met or not, as well as how many nodes were computed.
   • Failed to Converge - This result shows how many nodes were unable to converge on a solution based upon the criteria specified in the Fire Flow Alternative.
   • Satisfied Constraints - Shows how many junctions satisfied the fire flow constraints specified.
   • Failed Constraints - Shows how many junctions failed the fire flow constraints specified
   • Total Nodes Computed - Shows how many fire flow nodes were computed.
     
8. Viewing the Fire Flow Tabular Report Results:

•   Close the Calculation dialog box and click the Tabular Reports button from the toolbar or click Report, then Tables.

• Select Fire Flow Report.
  
• Click OK.
  

Fields in the Fire Flow Report

1. Label - Label of junction in system.
2. Zone - Corresponding pressure zone of junction.
3. Fire Flow Iterations - The number of iterations done to compute results.
4. Fire Flow Balanced? - Check box indicating whether calculations were successfully balanced during iterations.
5. Satisfied Fire Flow Constraints? - Check box indicating whether the specified fire flow was met.
6. Needed Fire Flow - Shows specified needed fire flow for calculation.
7. Available Fire Flow - Shows the available amount of water at the junction at the calculated residual pressure.
8. Total Flow Needed - Shows the amount of total flow needed at the junction during calculation. If the option to add the fire flow to the baseline demand was used, this field will show the needed fire flow plus the demand at the junction.
9. Total Flow Available - Shows the available fire flow plus the baseline demand if the option to add the baseline demand was used. If no baseline demand was added to the calculation this will show the available fire flow only.
10. Residual Pressure - Shows the specified residual pressure used during the calculation. Typically this is 20 psi.
11. Calculated Residual Pressure - Shows the pressure that was calculated for the available fire flow.
12. Minimum Zone Pressure - Shows the minimum zone pressure that was specified during setup of the analysis
13. Calculated Minimum Zone Pressure - Shows the lowest pressure calculated in the same pressure zone as the junction that had the fire flow calculated.
14. Minimum Zone Junction - Displays the name of the junction with the lowest zone pressure which corresponds to the calculated minimum zone pressure column.
15. Minimum System Pressure - Displays the minimum pressure specified across the system when this option is turned on.
16. Calculated Minimum System Pressure - Displays the minimum pressure in the system for each junction's fire flow calculation
17. Minimum System Junction - Displays the name of the junction with the lowest pressure across the entire system and corresponds to the calculated minimum system pressure column.

See Also

WaterCAD product information

WaterGEMS product information

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

eSeminar on Fire Flow Analysis in WaterCAD 7.0 (Recommended)

WaterCAD User Guide

WaterGEMS User Guide

Advanced Water Distribution Modeling and Management online textbook

Bentley LEARN Server

Overview

Pressure Dependent Demands (PDD) allows you to perform a hydraulic simulation in which the nodal demand is treated as a variable of nodal pressure. This TechNote describes how to set up a PDD simulation in WaterCAD, WaterGEMS, and HAMMER, and also provides suggestions for PDD input data.

Background

Some types of water demands are volume-based, in that the demand is independent of available pressure. Examples of volume-based demand sources are washing machines, dishwashers, and toilets. Other demands are pressure-dependent, meaning water usage decreases with a decrease in pressure. Pressure-based demand examples include showers, sprinklers, and leaks.

Typically, water modeling programs assume that all demands are volume-based, and maintain the user-input demand regardless of the calculated available pressure. Although this assumption works well under the normal range of pressure conditions, it loses accuracy if an episode such as a fire or pump outage causes a significant decrease in system pressure.

One option for modeling demands that vary based on pressure is to set up model nodes as simple flow emitters. Because the flow emitter approach places no upper limit on the amount of water demanded with increasing pressure, it is most useful for determining water consumption by a free-discharge element such as a sprinkler or broken pipe. However, other pressure-based demand types result in no additional consumption once the pressure is above a certain threshold value, such that use of flow emitters in the model could skew water consumption to be unrealistically high in higher-pressure areas. Another limitation of flow emitters is that they will result in calculation of a negative demand, or inflow, when the pressure is negative.

WaterCAD and WaterGEMS V8 XM and V8i have a Pressure Dependent Demands (PDD) feature that allows for more control over demand calculation. In many instances where pressure affects water use, the PDD feature will provide a more realistic result than simply placing flow emitters on nodes.

Using PDD, you can:

• Analyze pressure-dependent demands at a single node, subset of nodes, or all nodes
• Define the reference pressure at which 100 percent of the specified reference demand can be met
• Define the threshold pressure beyond which an increase in pressure results in no additional demand increase
• Combine PDD and volume-based demands at individual nodes
• Determine the actual supplied demand at a PDD node, as well as the demand shortfall
• Obtain a result of zero for pressure-dependent demands when the pressure is less than or equal to zero
• Present the calculated PDD and the associated results in a table and graph

Setting Up the PDD Function

1. Go to Components > Pressure Dependent Demand
2. Click the New button to create a new PDD function
3. The Function Type can either be Power Function or Piecewise Linear
   1. The Power Function option is used to define the exponential relationship between the nodal pressure and demand. The ratio of actual supplied demand to the reference demand (i.e., percentage of defined nodal demand designated as pressure-dependent) is defined as a power function of the ratio of actual pressure to reference pressure. (Defining of reference pressure and pressure-dependent demand percentage is done in the Alternative, as described in the next section.) Using a power equation for your Pressure Dependent Demands is like you are assuming that each 'demand' in your system acts like an orifice. The orifice equation can be written like this: Q = K*P^0.5 Where Q is flow through the orifice, P is pressure upstream of the orifice, and K is some coefficient (which is a function of orifice area, coefficient of discharge, etc.) You can specify a desired Power Function Exponent. The default value provided is 0.5, which is the exponent used in the orifice equation.  By checking the box for "Has Threshold Pressure?" you can define a pressure value that maximizes the computed pressure-dependent demand (i.e., demand remains constant when the pressure exceeds the threshold value). If you do not define a threshold pressure, demand will increase with pressure regardless of how high it is. Since many PDD simulations are focused on the effects of lower pressure conditions, it is often not necessary to define a threshold pressure. 
      
      See the screenshot below for Power Function:  
      
      
      
      Example: If pressure on J-10 is 40% of the Pressure (Reference) set in the Pressure Dependant Demand Alternative (explained below), then going by the graph above (or by computing 0.40^0.5), the demand on that given junction will be 63.2% of what was set initially. In other words, if J-10 had a demand of 100gpm, and the Pressure (Reference) is set to 150psi, then if pressure on J-10 drops to 60psi (which is 40% of the 150psi), the demand will not be 100gpm any more--it will be 63.2 gpm.

       

      The Piecewise Function allows you to manually specify the relationship between reference pressure and demand, as shown in the screenshot below:
      
      
      
      Example: If pressure on J-10 is 65% of the Pressure (Reference) set in the Pressure Dependant Demand Alternative (explained below), then going by the table above, the demand on that given junction will be 80% of what was set initially. In other words, if J-10 had a demand of 200 gpm, and the Pressure (Reference) is set to 150psi, then if pressure on J-10 drops to 130psi (which is 65% of the 200psi), the demand will not be 100 gpm anymore, it will be 80 gpm.

   Create a Scenario that Assigns a PDD Function to an Alternative

   This section describes how to create and configure a new Scenario and Alternative to run your PDD analysis.

   1. Go to Analysis > Scenarios. Create a new Scenario.
   2. Double-click on the scenario you just created. Click on the drop-down menu right next to Pressure Dependant Demand. Click on New.
      
   3. Assign a name to the new alternative or keep the default as Pressure Dependent Demand Alternative - 1
   4. Go to Analysis > Alternatives. Expand the Pressure Dependant Demand alternative and double-click on the one you just created.
   5. Select the Global Function you created earlier. See screenshot below:
      
   6. Set the Pressure (Reference), or check the Reference Pressure Equals Threshold? box if you want it to apply.
   Often, the Reference Pressure will be defined as the typical pressure at a node under typical demand conditions. However, if you are analyzing pressure-dependent demands for multiple nodes with significantly different typical pressures, you will need to override this system Reference Pressure on a node-by-node basis, as described in the next section.
   1. You can set a percentage of the demand that can be pressure dependent. For example, in that case that J-10 has a demand of 200 gpm, you can set 20% (40 gpm) that will not be affected regardless of pressure changes on that node, and the rest of the 80% (120 gpm) will comply to the Pressure Dependent Demand function. If that doesn't apply, keep Percent of Demand that is Pressure Dependent to 100%
      
   2. Click on Close.

   Assigning PDD on Specific Nodes

   1. To override the PDD settings locally on specific junctions, go to the Junction/Hydrant Tab on the Pressure Dependent Demand Alternative window.
   2. Check the box under "Use Local Pressure Dependent Demand Data?" Then, select the Local Function from the drop-down menu (you can also create a different PDD function that can be used on selected junctions).
   3. Check the Reference Pressure Equals Threshold? or set the Pressure (Reference), if it applies.
   4. You may want to set the Reference Pressures for your nodes equal to their "typical" pressures, as computed in a separate representative Scenario. One way to do this is to:
      1. Go to your "typical" scenario, open a junction table, sort it by ID, click the first cell in the Pressure column, hold the Shift key, and click the last cell in the column. Then, CTRL+C to copy the data to your Windows clipboard.
      2. Return to your PDD alternative, go to the Junction tab, and right-click and Global Edit the "Use Local Pressure Dependent Demand Data?" column to set all values to TRUE.
      3. Sort the junctions by ID.
      4. Click the Pressure (Reference) column heading to select the cells in that column, then CTRL+V to paste pressure values from your clipboard. Spot check the pressures to be sure they pasted correctly.
         
         

   Set up Calculation Options

   1. You'll also need to set up the Calculation Option for the new scenario you created. Go to Analysis > Calculation Options.
   2. Click on New button. Double click on the newly created calculation option.
       
   3. Set Use Pressure Dependent Demand? to True.
   4. For Pressure Dependent Demand Selection you can either choose or a Selection Set (with nodes where the PDD alternative will apply to, with all the rest always using their regular demands) you created from that list.
   5. Now, assign this Calculation Option to the PDD scenario, by double-clicking on the scenario, then choose the PDD calculation option under the Calculation Option drop down menu.
      
      
      
      Now you can run the scenario.

    Additional Resources: eSeminar by Dr. Tom Walski

4. See Also

   Product TechNotes and FAQs

   Haestad Methods Product Tech Notes And FAQs

   [[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]

    

   External Links

   Bentley Technical Support KnowledgeBase

   Bentley LEARN Server

Thanks for the suggestions

Overview

This Technote explains how to interpret and troubleshoot calculated results for an automated fire flow analysis in WaterCAD or WaterGEMS V8 XM or V8i. Before reading this Technote, it is recommended that the user complete the Fire flow Quick start lesson. This is located in the WaterCAD/WaterGEMS help, under Contents > Quick Start Lessons > Automated Fire Flow Analysis.

Background

Fire Flow analysis is a common tool used in WaterCAD and WaterGEMS to ensure enough protection is provided during fire emergencies. The user is able to enter constraints in order to determine how much fire flow is available at hydrants while adequate system pressure is maintained. Several tools available to aid in understanding fire flow results.

How Does Automated Fire Flow Work?

Fire flows are computed at each node by iteratively assigning demands and computing system pressures. When you execute a fire flow analysis, WaterCAD\GEMS will:

1. Calculate a steady-state simulation for all nodes designated as fire-flow nodes. At each node, it begins by running a Steady-State simulation using only non-fire demands, to ensure that the fire flow constraints (e.g., minimum residual pressure, minimum zone pressure) that have been set can be met without withdrawing any Fire Flow from any of the nodes.
2. Evaluate the Fire Flow Upper Limit and Available Fire Flow at each of the fire-flow nodes.Assuming the fire flow constraints were met in the initial run, the program performs a series of steady-state runs in which flow is applied to each specified fire-flow node and results are evaluated against fire-flow constraints. Note that the fire flow for each individual node is evaluated using a separate analysis (i.e., needed fire flow is not applied simultaneously to all fire-flow nodes).
   1. The program performs a series of steady-state analyses in which the Fire Flow Upper Limit discharge is applied to each node in turn. If the fire flow constraints are met for the Fire Flow Upper Limit discharge, the node satisfies the fire flow constraints and no further analysis is required for that node.
   2. The program then performs a series of steady-state analyses in which it iteratively assigns lesser demands to nodes that do not meet Fire Flow Upper Limit constraint to determine the Avalable Fire Flow. The Available Fire Flow is the maximum fire flow that each node can supply without violating fire flow constraints.
   3. If the Available Fire Flow is greater than or equal to Needed Fire Flow, the node satisfies the fire flow contraints. If Available Fire Flow is less than Needed, it does not.
3. Run a final Steady-State calculation that does not apply Fire Flow demands to any of the junctions. This provides a baseline of calculated results that can then be compared to the Fire Flow conditions, which can be determined by viewing the results presented on the Fire Flow tab of the individual junction editors, or in the Fire Flow Tabular Report. 

Interpreting the Fire Flow Alternative 

Configuration for an automated fire flow analysis is done under the Fire Flow alternative. This is found under Analysis > Alternatives > Fire flow. When computing a scenario, the fire flow alternative assigned to that scenario is used.

At a minimum, you should specify values for the needed Fire Flow, Fire Flow Upper Limit, Apply Fire Flow By, Residual Pressure Lower Limit, Zone Pressure Lower Limit and Fire flow nodes selection set. Below is an explanation of each of the main fields found in this alternative (when double clicking on it): 

Note: If the above options need to be configured differently for each junction/hydrant, you can specify "local" fireflow constraints by clicking the "specify local fireflow constraints?" check box next to the junctions/hydrants in the list at the bottom of the fireflow alternative. If this box is not checked, that particular fireflow node will utilize the global constraints entered at the top of the fire flow alternative.

  Note: it is important to understand that for the minimum zone pressure constraint, the program checks pressures for all other nodes in the model that are assigned to the same zone as the fireflow node in question. The zone is an attribute of the node. Say for example there are two nodes in the fireflow selection set: J-1 and J-2. J-1 is assigned to Zone A and J-2 is assigned to Zone B. Fireflow nodes are checked independently during the analysis, so when J-1 is being computed, the program will check pressures at all other nodes that are also assigned to Zone A and compare against the minimum zone pressure constraint. Then, when the analysis moves on to J-2, it will be checking pressure at all nodes assigned to Zone B. So, the program isn't running a fireflow analysis on a particular zone - it considers pressures at nodes assigned to certain zones, based on the fireflow node it is currently analyzing.

Configuring your model to run a fire flow analysis 

After you've configured your fire flow alternative, the next step is to assign that alternative to the scenario you would like to compute.

1. First, go to Analysis > Calculation Options. If you have an existing calculation option set that you're using in other scenarios, click on it and click the "duplicate" button. If you'd like, you could also click the "new" button to create a new calculation option set. Provide a meaningful name for your new calculation option set and double click it to open the properties. In the properties, set the Calculation Type to Fire Flow. 

2. Next, go to Analysis > Scenarios. Create a new scenario by choosing New > base scenario, or right click an existing scenario and choose "child". Provide a name for the new scenario, such as "Automated Fire Flow Analysis".

3. Double-click your fire flow scenario to open the properties. Select your fire flow alternative from the dropdown next to "Fire Flow" and select your fire flow calculation option from the dropdown next to "Steady state/EPS solver Calculation options".

4. Make your fireflow scenario current by right clicking it's name in the scenario manager and choosing "make current" or by selecting it from the Scenario dropdown menu bar at the top of your WaterCAD/WaterGEMS window.
5. At this point, the automated fireflow analysis can be computed by going to Analysis > Compute. To understand the process that WaterCAD/GEMS uses, please see the section further above, entitled "How does the automated fire flow routine work?".

Interpretting Automated Fire Flow Results

There are several ways you can view the results of your automated fire flow analysis. Below describes the most common.

Using the Fire Flow Report

1.  Make sure that your Fire Flow Analysis scenario is the current scenario and that you've succesfully computed it.
2. Click Report > Element Tables > Fire Flow Report. The Fire Flow report is essentially a custom flextable including only the relevant fire flow results for both junctions and hydrants. The fields seen here can be added to the junction and hydrant flextables, but it is generally more convenient to use and keep this separate fireflow flextable when reviewing results of an automated fire flow analysis.

Note: if you look at the general results in other flextables, such as "pressure" in the junction table, you will be viewing the baseline steady state results for your model, without any fire flow demands present. It is recommended that you only look at the fireflow table, so as not to be confused.

The first thing you will notice is a column titled "Satisfies Fire Flow Constraints?" This will be checked only if the particular fire flow node (designated by the "label" for each row in this report) can provide at least the needed fire flow, while satisfying the fire flow constraints - the pressure constraints and sometimes the velocity constraints, if applicable.

Here is a description of some of the other fields (columns) available in the fire flow report:

Note: if your table does not display one or more of the below fields, you can add it using the yellow "edit" button at the top of the flextable. 

Using the Fire Flow Results Browser

The Fire Flow Results Browser will allow you to check results for others elements in your model, during individual fire flow runs. Normally, the only results available after a fire flow analysis are the residual pressures at each fireflow node and minimum zone/system pressures. If you'd like to see other results, such as pipe velocities, hydraulic grades, valve status, etc, during a specific fire flow test, you can use this tool. First, you'll need to make sure that you have set up your Fire Flow Alternative for this function before running the fire flow analysis:  

After you have set up your Auxiliary Output Settings and run the Fire Flow analysis, go to Analysis > Fire Flow Results Browser.  

Select a fire flow node from the list to see the results for its adjacent pipes, and for the elements included in the output selection set (defined in the fire flow alternative). With a fire flow node selected, you can then establish color coding, annotations or simply check auxiliary results using the elemenet properties or flextables. For example, if you wanted to see the status of Valve X when Hydrant Y was flowed, click Hydrant Y in the list and then open the properties of Valve X. 

Color Coding Fire Flow Results 

Another good way to review an automated fire flow analysis is to use color coding. For example, you can color code junctions and hydrant based on the values for total available fire flow, to see areas where the available fire flow is lacking. Another useful color coding could be one based on the "satisfies fire flow constraints?" attribute. For example, you could color code such that junctions with "false" for this attribute show up as red, with a larger size. This would be done by using the "color and size" option, in the color coding dialog. 

You can also use color coding with the fire flow results browser. For example, you could color code pipe velocities so that when you click fire flow nodes from the fire flow results browser list, the colors will update to show the velocity distribution when that particular node was flowed.  

Troubleshooting

Fire flow results not available 

In some cases, you may notice that the results in your fire flow report show "N/A" after computing the model.  

1. Make sure your scenario is set up correctly. Ensure that the correct fire flow alternative is assigned to the scenario that you are computing and ensure that its calculation options have the calculation type set to "fire flow". If this is set to "hydraulics only", fire flow results will not be computed.
2. Make sure the scenario computed succesfully. If any messages show up under your user notification (Analysis > User notifications) with a red circle next to them, it means that the calculation failed. You'll need to address these fatal errors first, before results will be available. 
3. "N/A" entries can also be caused by omission from the fireflow selection set. In your fire flow alternative, make sure that all the nodes you'd like to study are included in the selection set selected for "Fire flow nodes". The fireflow routine will only analyze and provide results for nodes in this selection set. If desired, a filter can be used in the fire flow report so that nodes not included in the fire flow nodes selection set are not displayed.
4. Make sure that you are not trying to use the fire flow results browser, if you haven't set up your fire flow alternative to save auxiliary results. Doing so can cause results in the fire flow flextable to show "N/A". This can be fixed by clicking the "reset to standard steady state results" button at the top of the fire flow results browser.

Understanding why a node cannot provide the desired fire flow

In the fire flow report (flextable), you may notice that one or more fire flow nodes does not satisfy the fire flow constraints. Meaning, the total available fire flow is less than the needed fire flow or below what you expected. There are several reasons why this could occur.

1. First, check the calculated residual pressure field. This is the pressure at the fire flow node, at the total available fire flow. So, if this is equal to the residual pressure constraint, it means that the residual pressure constraint would be violated if any more flow was passed, so the fire flow routine stopped. If the calculated residual pressure is less than the residual pressure constraint, it probably means that the residual pressure was below the constraint even with the base demands (with no additional fire flow added). In this case, you should check the pressures in the model with baseline demands - they should all be above the constraints entered in the fire flow alternative.
2. Next, check the calculated minimum zone pressure field. This is the lowest pressure out of all nodes in the same zone as the fire flow node in question, at the total available fire flow. So, if this is equal than the minimum zone pressure constraint that you entered, it means that the fire flow constrainted would be violated if any more flow was passed. So, the fire flow calculation stopped and reported the total available fire flow such that this would not be violated. If the calculated minimum zone pressure shows as less than the constraint, it probably means that the pressure somewhere else in that zone was less than the constraint, even with only the base demands (with no additional fire flow added). You should check the pressures in the model with baseline demands - they should all be above the constraints entered in the fire flow alternative.

   
   To check which specific node had the lowest pressure in the zone, check the "Junction with minimum pressure (zone)" field. In many cases, this may be a node at the suction side of the pump or at some other location that you may not be concerned with. In this case, it is recommended that you assign a different zone to these nodes. For example, create a zone called "low" and use that. This way, it won't be in the same zone as any fire flow nodes and thus won't be considered (unless you're using the minimum system pressure constraint).

3. If you elected to use the minimum system pressure constraint in your fire flow alternative, you'll also need to check the calculated minimum system pressure. This is identical to the zone pressure constraint (see above), except it checks pressure at ALL nodes in the model. You can also check the "Junction with minimum pressure (system)" field to see which node caused the fire flow routine to stop.
4. If you elected to use the Velocity constraint in your fire flow alternative, you'll also need to check the "Velocity of maximum pipe" and "Pipe w/ Maximum Velocity" fields. If the velocity in any pipe inside the chosen "pipe set" selection set exceeds the constraint you entered, the fire flow routine will stop. So, similar to the pressure constraints, you may notice the "Velocity of maximum pipe" is equal to or less than the constraint, indicating the reason why no additional fire flow could be extracted.
5. Lastly, in rare cases, the fire flow routine may stop at a certain Total Available fire flow due to an unbalanced model. Meaning, at certain flow rates, the steady state simulation may not be able to converge on a balanced hydraulic solution within the maximum number of trials. This can occur in large, complex models, with low or near-zero flows, and/or when other data input in the model is not correct. It causes the results to be invalid and the fire flow run to stop. 

   
   If your available fire flow is less than the upper limit, yet all the constraints described above are not violated, chances are that this was caused by the network becoming unbalanced. To check, try running a manual fire flow analysis on that junction. For the manual run, just make sure the calculation type in your calculation options is set to “Hydraulics only” and that you have entered the value for the total needed fire flow as an additional, fixed demand on that junction. Run the analysis and check your user notifications for an unbalanced error. One solution to this is to increase the max trials value in the calculation options, but you should also consider investigating other causes, such as data entry errors.

Note: be aware of the presence of local fire flow constraints. At the bottom of your fire flow alternative, you can set node-specific constraints, which override the global constraints set at the top. This could potentially cause confusion when viewing fire flow results. For example, the total available fire flow for a certain node may be less than what you believe the needed fire flow value is, but still showing as satisfying the fire flow constraints. If you had a local "needed fire flow" set to a lower value, this could be valid. So, make sure you include and check the "Fire flow (needed)", "Fire flow (upper limit)" "Pressure (residual lower limit)" and "Pressure (Zone lower limit)" fields in your fire flow report/flextable.

Consider the following Fire Flow Flextable, with no minimum system pressure or maximum velocity constraints used:

J-10 - This node passed the fire flow test, as indicated by the "Satisfies fire flow constraints?" check box. It reports a Total available fire flow of 2012.68gpm, which is above the total needed fire flow of 462.68. Although the needed fire flow is actually 450.00gpm, we have chosen to add fire flows to base demands, and there is a base demand of 12.68gpm on this node. The total available amount of 2012.68gpm accounts for this base demand as well. Meaning, the total demand on this particular node can be up to 2012.68gpm without violating any fire flow constraints. The reason is because at the upper limit (2012.68gpm), both the residual pressure and minimum zone pressure are 59.2psi, which is above the constraints. The fire flow analysis stopped at the upper limit value to prevent unrealistically high flows from being computed. 

J-169 - This node passed the fire flow test with a reported total available fire flow of 557.82gpm. This is above the needed fire flow but below the upper limit. The reason why the fire flow test stopped at this flow is because a higher flow rate would violate the zone pressure constraint. As you can see, the calculated minimum zone pressure (lower limit) is equal to the user-entered minimum zone pressure constraint of 20psi and the "junction w/ minimum pressure (zone)" shows J-170. This means that although the residual pressure at J-169 (24.3psi) is above the constraints, J-170 is in the same zone as J-169 and had the lowest pressure, 20psi. 

J-171 - This node passed the fire flow test with a reported total available fire flow of 489.28gpm. This is above the needed fire flow but below the upper limit. The reason why the fire flow test stopped at this flow is because a higher flow rate would violate the residual pressure constraint. Although the minimum zone pressure of 23.5psi is above the 20psi constraint, the residual pressure (calculated pressure at J-171) is equal to the residual pressure constraint of 15psi. At a higher flow rate than 489.28gpm, the residual pressure would drop below 15psi, which would violate the pressure constraint. So, the fire flow analysis reports the maximum flow available without violating the constraint. 

J-159 - This node failed the fire flow test, as indicated by the unchecked "Satisfies fire flow constraints?". This is because the total available fire flow is 327.06gpm, which is less than the total needed flow of 453.17gpm. The reason why this node can only supply 327.06gpm is because of the residual pressure constraint. As you can see, even though the minimum zone pressure (60.4psi) is well above the zone pressure constraint, the calculated residual pressure is equal to the residual pressure constraint. This means that the pressure constaint would be violated at a flow any higher than 327.06gpm. 

J-154 - This node failed the fire flow test, because the available fire flow of 289.24gpm is less than the needed fireflow of 455.39. The reason it can only supply this much flow is because of the minimum zone pressure constraint. As you can see, although the residual pressure (28.5psi) is above the constraint, the minimum zone pressure is equal to the constraint, with J-158 as the "junction w/ minimum pressure (zone)". This means that J-158, which is in the same zone as J-154, is preventing any additional flow from being extracted, without violating the minimum zone pressure constraint. 

J-1 - This node failed the fire flow test with a total available flow of zero. This means that even without any demand at all on J-1, the baseline pressures in the model fall below the constraints. This is indicated by the calculated residual pressure of -1.4psi. This means that with zero demand on this node, the pressure at J-1 is -1.4psi. Since this is well below the constraint of 20psi, the fireflow test fails and the available fire flow is reported as zero. This particular junction is located on the suction side of a pump station, so it probably should be excluded from the fire flow nodes selection set. Meaning, it is probably unnecessary to compute fire flow for this node. 

J-2 - This node also failed the fire flow test with a total available flow of zero. In this case, it is because the minimum zone pressure constraint was violated. This means that without any demand at all on this node, the pressure at J-1 is -1.4psi. J-1 is in the same zone as J-2 and as seen above, it is at the suction side of the pump. So, assigning a new zone to J-1 should resolve this problem, since it would no longer be considered during the check of zone pressure. 

J-3 - This node, along with other junctions below it, show "N/A" for all calculated fields. This is because these nodes are not included in the fire flow nodes selection set, set in the fire flow alternative. 

Fire flow results browser not working

If you attempt to use the fire flow results browser tool, you may run into problems if it is not configured correctly. Symtoms could be: 

1. Nothing showed up in the list.
2. Some results show "N/A" in the properties/flextables after clicking a fire flow node from the list.

This is caused by improper configuration in the fire flow alternative. Open the fire flow alternative and check the "Auxiliary output Settings" section. If you'd like to be able to check auxiliary results for any fire flow node, regardless of whether it passed or failed the "needed fire flow", select "All nodes" for the "Fire flow auxiliary results type". Doing this will ensure that all nodes show up in the list. At this point, at a minimum, you will be able to see auxiliary results for pipes adjacent to the fire flow node that you select in the results brower. If you'd like to see results for more elements, you'll need to choose a selection set for the "Auxiliary output selection set". If you want to be able to see auxiliary results for all nodes, you can create a selection set of all nodes. To do this, close the fire flow alternative, go to Edit > Select All. Right click anywhere in the drawing pane, choose "create selection set" and give it a name, such as "ALL ELEMENTS". Then, select this in your fire flow alternative for the output selection set. Now, when you compute the fire flow simulation, you'll be able to check results for all elements in the model, for your fire flow nodes.

Note: the more fire flow nodes available in the list and the more elements included in the output selection set, the longer the calculation will take to perform and the more disk space it's saved results will take up.

Frequently Asked Questions

WaterGEMS V8 Automated Fire Flow FAQ 

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

WaterGEMS V8 Automated Fire Flow FAQ 

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]  

WaterGEMS V8 Modeling FAQ 

External Links

Water and Wastewater Forums

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

Often, new water models are constructed by first importing much of the network data from a GIS data source such as a geodatabase. However, GIS data is frequently updated as more is learned about the system, new facilities are constructed, or old facilities are abondoned, for instance. Therefore, it is often necessary to update the water model with new information from GIS as it becomes available The ModelBuilder tool in WaterCAD/WaterGEMS provides the means to do this.

With ModelBuilder, you can import, create, and update both a GIS or other databases and water model files. The process described in this TechNote will demonstrate how to add new elements, as well how to update existing elements in the water model from from a geodatabase file.

This TechNote is a continuation of "Building A Model Using Model Builder;" however, it can be used independetly. The procedure described here uses a geodatabase as a source of modeling information and WaterGEMS as the modeling software. However, ModelBuilder supports a variety of other data source formats, and analogous steps can be followed in other Bentley modeling software applications such as SewerGEMS, SewerGEMS Sanitary, StormCAD, and SewerCAD.

Note: You will only be able to establish a connection to an ArcGIS geodatabase data source if you are running WaterGEMS (or SewerGEMS, or SewerGEMS Sanitary) within the ArcMap interface. However, other data source types are available when working within other interfaces (Stand Alone, Microstation, or AutoCAD) or when using non-"GEMS" software.

For this example, we will assume that the GIS data source has been updated with a new well.  Also, the existing discharge line has been abandoned and replaced with a new 20" line. So, for this update, ModelBuilder should do the following:

1. Add the new well system , which includes adding:
   1. the new well as a reservoir element
   2. the well pump
   3. a pipe connecting the well to its pump
   4. a junction
   5. a pipe connecting the pump to a junction
2. Split an existing pipe
3. Abandon an existing pipe (Deleted from source file so remove from model)
4. Add new discharge line

Preview of Source File

As mentioned, for this example the source file of modeling information is a geodataBase (GDB). This GDB contains four modeling elements (or hydraulic features).

1. Well
2. Tanks
3. Pump
4. Pipe

The modeling attributes in each of the features are shown below.

Updating the Model Using ModelBuilder

The steps below describe how to update the existing model. Some of the screens may look different depending on the source data you are using.

Open ModelBuilder

Choose ModelBuilder from the Tools menu, and ModelBuilder will open.

The initial window (see below) shows previously created database connections. For this example, we will assume that any databse connections previously used with our system have been deleted. If an applicable link were already present, it could be double clicked for more details, or the "Sync In" button could be used to update the model from the database.

For our example, click the New button shown to create a new database connection.

Specify the Data Source

After you intiate a new connection, the "Specify your Data Source" dialog appears. First, select the data source type (ArcGIS Geodatabase Features in our example), and then click Browse to identify the source file. 

Also on this screen, you can:

• Select which source data to use
• Select or deselect tables/ layers to be used
• Add an SQL query that can be applied to filter the table if required
• Preview the source data table

When the "Show Preview" box is checked, only the highlighted Table from the left will be displayed. Remember, if existing link is double clicked then the changes should be seen in the preview. If the changes are not there, start new model builder by clicking on "New" button on the first screen of ModelBuilder. In the image below, notice the number of pipes are different.

 Click Next.

Specify Spatial and Connectivity Options

 Depending upon the source file this screen may look different. In this step, first provide the unit of your Source Data. If not sure try with "ft". Second, "Create nodes if none found at pipe endpoint"; when this box is checked, ModelBuilder will create a pressure junction at any pipe endpoint that: a) doesn't have a connected node, and b) is not within the specified tolerance of an existing node. This field is only active when the Establish connectivity using spatial data box is checked. (This option is not available if the connection is bringing in only point type geometric data for example, Well or Wet-Well.)

 Note: Pipes will be connected to the closest node within the specified tolerance. The unit associated with the tolerance is dictated by the Specify the Coordinate Unit of your data source field.
Click Next.

Specify Element Create/Remove/Update Options

Depending upon the requirement the selection of options may vary. For this particular example following options are selected.

 Note: For detail information, press F1 and help file will be launched.
Click Next.

Specify Additional Options

This step is particularly important if the source file has Unique ID. In this workflow, there is a unique ID so GIS-ID has been selected. If there is no unique ID, Label will work the same. If Sync Out feature (updating the source file based on model updates) is planned to use then maintaining Unique ID is highly preferred. Help file explains each options in details, press F1 to launch help.

 Click Next.

Specify Field mappings for each Table/Feature Class

If the existing link had been double clicked then everything in this step should be good. If a new button had been clicked then all the necessary elements and the fields need to be mapped. Follow the "Specify Field mappings for each Table/Feature Class" from "Create A Model Using ModelBuilder" and come back to this step.
Click Next.

Create Model Now?

 Select "Yes" and click on "Finish".

Click Finish.

ModelBuilder Summary

Close the Summary after reviewing.

Click "Yes" in the next screen (below).

Finally the screen should look like below. Notice the existing features are turned off and new layers of the WaterGEMS are checked.

This concludes the model updating process using ModelBuilder.

See Also

Building A Model Using Model Builder

Updating Source File Using Model Builder

Setting Boolean (True/False) Fields using Modelbuilder

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs 

WaterGEMS V8 Modeling FAQ 

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Water and Wastewater Forum

Overview

It's always a huge challenge to maintain the synchronization between the source file and the Model. With the latest release of V8i, the powerful ModelBuilder got even powerfull and now we can update the source file also.

This is continuation of the "Building A Model Using Model Builder" and "Updating A Model Using Model Builder"  however it can be used independently. These steps can be followed in several modeling software applications like, WaterGEMS, WaterCAD, SewerGEMS etc. The procedure described below uses GeoDataBase as an original source of modeling information and WaterGEMS as a modeling software.

Mantra, when updating source file, "The Hydraulic model is now source file and the GIS data is the target"

Let's assume the Hydraulic model got updated. An existing pipe got tapped in two places and a new loop of 8" pipe is established. With this update the ModelBuilder should do the following to the source file:

1) Split the existing pipe in two places (Meaning, create new features in source file)
2) Update the pipe attributes (Meaning, update the pipe information in source file)

Preview of Source File

Symbology has been applied to the modeling elements to better illustrate the updates.

Following image will show the population of the Unique ID in Pipe Table.

Updating Source File Using ModelBuilder

The steps described here will help to update the source file. This example updates the GeoDataBase source file however; any type of source file that was used to build the model can be updated. Before updating the source file directly it is recommended to make a back up copy of the source file that's planned to update by ModelBuilder.

Open ModelBuilder

  Tools > ModelBuilder

ModelBuilder, as shown below, will show up.
Let's assume a worst case scenario that the existing link got deleted or file name /path got updated. If filename/path is the same, the existing link can be double clicked.

Specify your Data Source

The "Specify your Data Source" will show up. First select the Data Source type and then ‘Browse' for the source file, as shown. If the existing link on ModelBuilder is double clicked, there should not be any warning messages and/or the missing Tables.

In this step,
- source data can be selected
- tables/ layers can be selected/ deselected
- SQL query can be applied to filter the table if required
- source table can be previewed

When "Show Preview" box is checked, only highlighted Table will be displayed. Remember, if existing link is double clicked then the changes should be seen in the preview. If the changes are not there, start new model builder by clicking on "New" button on the first screen of ModelBuilder.

 Click Next.

Specify Spatial and Connectivity Options

Depending upon the source file (Hydraulic Model elements) this screen may look different. In this step, first provide the unit of your Source Data. If not sure try with "ft".

 Note: Source file does not have any Junction attributes.
Click Next.

Specify Element Create/Remove/Update Options

Depending upon the requirement the selection of options may vary. For this particular example following options are selected.

 Note: For detail information, press F1 and help file will be launched.
Click Next.

Specify Additional Options

This step is particularly important if the source file has Unique ID. In this workflow, the Unique ID is maintained in "Label" field of the model so; the "Label" is selected in "Specify key field". If Source file has different Unique field then "GIS-ID" needs be selected. If there is no unique field in the source file then select "Label".

If the Unique ID field in source file name is say "WXYZ" then field "WXYZ" must be present in the Hydraulic Model. (User Data Extension from Tools menu is used to create "Custom" fields in Flex Table.) When new elements are created, Unique ID field (or WXYZ) will not be populated. As ModelBuilder will look for Unique ID under WXYZ field to update/create the new elements in source file, this Unique ID (WXYZ) must be populated with unique ID otherwise no new fields will be created.

 Click Next.

Specify Field mappings for each Table/Feature Class

If the existing link had been double clicked then everything in this step should be good. If a new button had been clicked then all the necessary elements and the fields need to be mapped. Follow the "Specify Field mappings for each Table/Feature Class" from "Create A Model Using ModelBuilder" and come back to this step.
Click Next.

Create Model Now?

 Select "No" and click on "Finish".

Click Finish.

Sync Out

Select the link that was just updated/used and click Sync Out.

Finally the screen should look like below with all the updates and new features as per the Hydraulic Model in the Source File. 

This concludes the updating of the source file process using ModelBuilder.

See Also

Updating A Model Using Model Builder

Building A Model Using Model Builder

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs 

WaterGEMS V8 Modeling FAQ 

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Water and Wastewater Forum

Overview

The purpose of this technote is to discuss common steps to calibrate a model using Darwin Calibrator in Bentley WaterGEMS. Additional information can be found in the WaterGEMS Help menu. 

Background

In order to accurately model a water system, the user will often need to calibrate the model. Darwin Calibrator allows the user to calibrate a model either manually or, with efficient genetic algorithms, in a more automated fashion. It allows for multiple calibration candidates to be presented so the best possible solution to a given system can be found. Solutions can also be exported into a new scenario for use in an existing water system.

Darwin Calibrator is included with a license for Bentley WaterGEMS V8. It is also available in Bentley WaterCAD V8 with an additional license configuration. 

Setting Up a Calibration Study

In order to calibrate a model, Darwin Calibrator makes adjustments to the pipe roughness, demand, and/or element status. For this reason, the first step for any calibration study is to have a completed model with all demand and roughness data entered.

With a completed model ready, you are set to start using Darwin Calibrator. You can open Calibrator by going to Analysis > Darwin Calibrator or by select the Darwin Calibrator icon.

The Darwin Calibrator window will then open.

To start a new calibrator study, select the New icon in the upper left and select New Calibrator Study. You will then see tabs and available features appear on the right part of the window.

The next step is to create your adjustment groups. While you can also set up the field data snapshots, it is recommended that the adjustment groups are created first, rather than let available data determine how many adjustment groups to have. For clarity, the focus will be on creating roughness groups, though the general steps will be the same for demand groups and status groups.

Go to the Roughness Groups tab. Click the New icon to create a new item. It is up to the engineer how many groups to create. The recommended workflow is to group elements that have similar characteristics such as age or material, since it can be assumed that two pipes of the same age or material will see similar changes to the actual roughness. To add elements to the roughness group, click the cell in the Element IDs column and select the ellipsis button.

A new window will open. Choose the “Select from Drawing” icon.

The Select toolbar will appear, allowing the modeler to choose elements from the drawing using a few different ways, including manual selection and query, among others. Once you have the elements selected, click the green check mark to complete the selection.

You will now see the elements in the table. Click Okay to return to Darwin Calibrator.

The selection of Demand and Status groups follow similar steps. Click the in the Demand Group or Status Element tab to select the elements.

Note: Status Elements are used when a particular part of the system is believed to contain a closed valve or pipe. It is recommended that Status groups contain one or very few pipes.

With the adjustment groups selected, now it is time to enter the field data snapshots. Return to the Field Data Snapshots tab. Make sure the representative scenario is set to the one to be used in the calibration study. Darwin Calibrator will pull results from a given scenario to compare to the adjusted values from the calibration study.

Next, select the New icon below the Field Data Snapshot tab. You will see a new field data snapshot appear.

Adjust the date/time information and identify a demand multiplier, if necessary. For example, if you have knowledge that your demand is higher or lower by a specific percentage, you can set that value here. The default value is 1.

Next, the observed data for the field data snapshot will need to be entered. This is entered in the lower right of the window, below the Observed Data tab. With the field data snapshot highlighted, click the New button under the Observed Target tab. A new line will appear with the Element cell blank.

Click inside the cell, and then click the ellipsis button. Select the element that you have the data for from the drawing, or use the Find option. Once you have selected the node, it will be available in the pulldown. With the node selected, the Attribute and Valve columns will be editable. Choose either Hydraulic Grade or Pressure for the attribute and then enter the appropriate value. Enter as many elements as you have field data for.

If you have a field data snapshot for another time during the model run, you can create a new one with a different time. You can then enter observed data for this time as well.

Next to the Observed Data tab is the Boundary Override tab. This is also important in a calibration study since it is possible that a tank level or pump/valve status is different from how it is depicted in the model. To get the most accurate results, applicable boundary overrides should be applied.

Click the Boundary Override tab and select the New icon below the tab. A new item will appear. Select the element as before, keeping in mind that this should be a tank, valve, or pump. Depending on the element chosen, the Attribute field will offer different selections. For a tank, the Attribute can be either Hydraulic Grade or Tank Level. For pumps and valves, setting and status are the options. Again, enter the appropriate value for the attribute selected.

Demand Adjustment is the last tab. This is used to adjust demand for individual elements, such as flow from a hydrant. Enter data here as necessary.

Manual Calibration Run

With the field data and boundary overrides entered, and the adjustments groups created, you are ready to run a calibration study. This section will discuss the manual calibration run. As before, the steps below will show a calibration study using roughness adjustment groups. Similar steps can be taken with demand groups.

The manual calibration study allows the user to enter multipliers or set values to change the existing roughness coefficient, demand, or status to a new value. After computing the study, you can compare the simulated results to the field data entered that given time.

To start a new manual run, click the New icon in the upper left and choose “New Manual Run”. A new item will appear below the calibration study label. On the right side of the window will be a series of tabs. In the roughness tab, you will see the roughness groups created earlier. To make a certain roughness group active, make sure the check box under “Is Active?” is checked. For the Operation column, choose either Multiply or Set, depending on which you wish to use. For Value, enter the appropriate value. Then click the Compute button.

Note: Multiple manual runs can be created so that a number of values can be entered for the roughness.

When completed a solution will appear that will include the results from the calibration study. Click “Solutions” directly under the manual run. This will display a fitness value for the solution or solutions. Fitness is a correlation between the observed data from the field data snapshot and the calculated value from the calibration study. The smaller the value, the better the fit. 

Returning to the left side of the window, click “Solution 1” to view the results. Under the Solution tab will be the adjusted roughness values for the pipes included in the calibration study. Under the Simulated Results tab will be the elements included in the field data snapshots. Columns for the observed data and the simulated data with the new roughness coefficients are presented, along with a column showing the difference between the observed and calculated values.

Optimized Calibration Run

The optimized calibration study uses a genetic algorithm to find the best possible solution available within certain parameters. The optimized calibration study has no true optimality and only knows the best solution relative to other solution already found during computation. However, the optimized calibration study runs through a large number of possible solutions and can often find a very good solution to fit the model.

The process is similar to the manual run. Click the New icon in the upper left and choose New Optimized Run. Under the Roughness tab, you will see the roughness groups created earlier. To make a certain roughness group active, make sure the check box under “Is Active?” is checked. For the Operation column, choose either Multiply or Set, depending on which you wish to use. Instead of entering a new value manually for the roughness, you will enter minimum and maximum values, as well as an increment. Then click the Compute button.

Darwin Calibrator will then try different values for roughness that fall within the values entered in the Roughness tab and compare the resulting values to the observed data from the field data snapshots. Darwin Calibrator will continue this until it finds the best solution available. The results are viewed just as the manual run, however there is an option to view as many as ten solutions. See the Tips section below for more information about this.

Updating the Model

If you are satisfied with the results, you can export the new roughness coefficients, demands, or status to a new physical alternative. To do this, highlight the solution you wish to export. The “Export to Scenario” icon will become active.

Choose this icon and a new window will appear.

To export to a new scenario, check the “Export to Scenario?” box. Do the same for the alternatives. With the check boxes selected the new results will be exported to new physical or demand alternatives (depending on the type of calibration study done). If you export to a scenario and do not export to an alternative (by unchecking the associated box or boxes), the data for that alternative type will be exported to the Base alternative.  

Note: The data in your original model will not change unless you use this export feature.

Tips

After computing a calibration study, you will sometimes see results that do not have a good fitness or do not make sense. Below are a few general tips to look at. More information on Darwin Calibrator can be found in the WaterGEMS Help documentation.

Try running a manual calibration study with no adjustments to the roughness or demand. In other words, keep the multipliers for the adjustments groups at 1. Then look at the fitness. If you have a very high fitness number, this is an indication that something is wrong with the model setup. Review your model and make sure the results look reasonable and that no unusual user notifications are generated.

Verify that the boundary overrides and demand adjustments are properly entered. This is very important since otherwise Darwin Calibrator will use values in the model at the times of the field data snapshots instead. Since the results in the model results might not be the same as what is actually occurring in the field, it is important to make these changes. Accurate data model-wide is important as well. Good, accurate data will mean the calibration study will work optimally.

If you are computing an optimized run, you can change some of settings in the Options tab. Highlight the optimized run on the left side of the window, then choose the Options tab on the right. Detailed information for the options can be found in WaterGEMS Help. Changing the Maximum Trials and the Non-Improvement Generations items to higher values will allow Darwin Calibrator to try more adjustments and possibly find better solutions. You can also change the Fitness Tolerance and the Solutions to Keep. It is recommended that the Advanced Options remain set to the default values.

Since Darwin Calibrator’s genetic algorithms can only compare a result to results that came before, making changes to the options can create new sets of solutions. It is recommended that you run several optimized runs even if the initial calibration study is good. A better solution might be generated after changing the parameters.

WaterGEMS and WaterCAD also come with a sample model that has completed manual and optimized calibration studies. This is a good resource to see the general setup of a calibration study, and can allow you to calculated models and see how the results differ not only with between manual and optimized runs, but also in changing the options. This sample can be found at the following file path.

C:\Program Files\Bentley\WaterGEMS\Samples\Example5.wtg

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

The purpose of this TechNote is to discuss common steps to design new pipe layouts and pipe rehabilitation projects using Darwin Design in Bentley WaterGEMS. Additional information can be found in the WaterGEMS Help menu. 

Background

Darwin Designer is an efficient method of designing new pipe layouts and pipe rehabilitation projects. It allows the user to design pipes for an existing model either manually or, with efficient genetic algorithms, in a more automated fashion. It allows for multiple design candidates to be presented so the best possible solution to a given system can be found. Solutions can also be exported into a new scenario for use in an existing water system.

Darwin Desginer is included with a license for Bentley WaterGEMS V8. It is also available in Bentley WaterCAD V8 with an additional license configuration. 

Getting Started

Darwin Designer is accessed by going to Analysis > Darwin Designer, or by clicking the Darwin Designer icon above the drawing pane.

Once Darwin Designer is open, click the New icon in the upper left select “New Designer Study”. An item will appear in the window on the left, and a series of tabs will appear at the top right. Next, choose either “New Manual Run” or “New Optimized Run,” depending on the type of study you will be conducting. A new item will appear below the name of the design study. These can be renamed.

The next step is to create your demand or rehabilitation groups. As stated above, Darwin Designer can be used to design new pipes or rehabilitate existing pipes. By entering pipes or pipe groups into these tabs, the program will know what type of study is being done. In other words, new pipe design and existing pipe rehabilitation must be done in separate Designer studies.

It can be efficient to apply more than one pipe to a given design or rehabilitation group. Darwin Designer will assign the same diameter to each pipe in the group (or all of the pipes in the same rehabilitation group will receive the same rehab action).

The steps to add pipes to a new design or rehabilitation group are the same. First, click the New icon. A new pipe group label will appear. A collection field will appear under the column “Element IDs.” Click in this cell and then click the ellipsis (“…”) button. This will open a new dialog where you can select the elements to go into the group.

Choose the “Select from Drawing” icon to open the Select toolbar. You can add or remove elements by activating the Add or Remove icon (Add is active by default). You can also add elements by drawing a polygon around a given group, or using a query. Selecting by selection set is available under the Query selection as well. Once completed, click the green checkmark icon. You will return to the previous dialog. Click Okay to return to Darwin Designer. Note that the collection cell will say that items are now included.

Next, go to the Cost/Property tab. Here you will enter the cost information for a given pipe size or rehabilitation action. To create a new item, choose the New icon and choose either “Design Option Groups” or “Rehabilitation Option Groups.” Next in the table on the right, begin to enter data. For Design Option Groups, enter the material, diameter, Hazen Williams C factor, and the Unit Cost. For Rehabilitation Option Groups, you will include an action, and then the diameter function, unit cost function, and roughness function for the pre- and post-rehabilitation scenarios.

Now go to the Design Type tab. Here you can select the Objective Type, and available budget for the project.

Now return to the Design Events tab. Choose the Representative Scenario from the pulldown. Darwin Designer will use data from the selected scenario when running the analysis. Next, select the New icon to create a new event. When you do this, you will see new information in the upper right of Designer dialog. Some of the fields will be unavailable to editing; this is pulled directly from the scenario assigned to the event. Items like minimum and maximum pressure and velocity will assure an efficient Designer run.

In the bottom right part of the Designer dialog, you can assign boundary overrides, demand adjustments, and pressure and flow constraints. These are used when the results calculated in the representative scenario might be different from when is observed in the field or allow a different set of constraints for certain elements.

Manual Calibration Run

Manual selections are used to force Darwin Designer to use specific designs in calculating costs of a new network design or existing rehabilitation study. The difference between the manual design run and the optimized design run is the Manual Selection column in the Design Groups and Rehabilitation Groups tabs. After you select a table to use for a group, you then set that group to use a specific pipe size or specific rehabilitation action.

Manual runs can be useful when you want to test hand calculations you have made or to reproduce an optimized design with some forced manual overrides for some pipes. You could also create a manual design run where you force the groups of pipes to specific sizes, since optimized design runs will choose the best fit.

To create a new manual design run, click the New icon and select “New Manual Design Run.” Go to the Design Group tab and select the Cost/Properties to be associated with the pipe group. Next, choose the size of pipe to be used for the manual run under the Manual Selection column. When you click the drop down, you will see a list of the pipe diameters assigned to the Cost/Property selection. It is possible to globally set the Cost/Properties column, but the Manual Selection column must to done individually.

To compute, highlight the manual design run and click the Compute icon. After completion, a solutions will be available to view and export to the model.

To view the results, highlight Solutions. This will display the fitness and total cost for each solution. To see the results from individual solutions, choose one of the solutions from the list. You will be able to view the breakdown of costs and the simulated model results for the solution.

Optimized Calibration Run

The optimized design study uses a genetic algorithm to find the best possible solution available within certain parameters. The optimized design study has no true optimality and only knows the best solution relative to other solutions already found during computation. However, the optimized design study runs through a large number of possible solutions and can often find a very good solution to fit the model.

The process is similar to the manual run. Click the New icon in the upper left and choose New Optimized Design Run. Under the Design Group or Rehabilitation Group tab, choose the Cost/Properties field associated with the pipe group. You do not need to manually select the size since Darwin Designer will do that for you. Once completed, click the Compute button.

Darwin Designer will then try different pipe sizes or rehabilitation actions that fall within the constraints entered in the Design Event tab until the best solution is found based on the objective type. Darwin Designer will continue until it finds the best solution available. The results are viewed just as the manual run, however there is an option to view as many as ten solutions. See the Tips section below for more information about this.

Updating the Model

If you are satisfied with the results, you can export to a new scenario, as well as new physical and active topology alternatives. To do this, highlight the solution you wish to export. The “Export to Scenario” icon will become active.

Choose this icon and a new window will appear.

To export to a new scenario, check the “Export to Scenario?” box. Do the same for the alternatives. With the check boxes selected the new results will be exported to new physical or active topology alternatives. If you export to a scenario and do not export to an alternative (by unchecking the associated box or boxes), the data for that alternative type will be exported to the Base alternative.  

Note: The data in your original model will not change unless you use this export feature

Manual Cost Estimating

Manual Cost Estimating is a method of estimating the construction cost of piping. This feature is available in Darwin Designer even for WaterCAD users with limited licensing features, such as no license for optimized or manual Designer runs.

After creating a new Designer study, go to the Cost/Properties tab. Select the New icon and choose “Design Option Groups.” Enter the material, Hazen Williams C factor, and unit cost for each diameter of pipe.

Next, go to the Design Group tab and click the New icon to create a new group. In the Element ID column, click the ellipsis button and choose the element or elements to be included. For Manual Cost Estimating, no information is needed in the tabs for Design Event, Rehabilitation Groups, or Design Type.

Next, click the New icon from above the left column and choose New Manual Cost Estimate Run. Highlight this run and click the “Is Active?” box for any pipe group you want included in the analysis. Choose the Design Option Group entered in the Cost/Properties tab in the Cost/Properties column. You can use the Global Edit feature to assign these. The other item to set up is the “Use Diameter from Representative Scenario” item. If this box is checked, this will assure that the costs are based on the diameter of the pipes in the scenario. If it is unchecked, you will need to manually enter the scenario to be used.

To compute the Manual Cost Estimating run, click the Compute icon. You will get a single solution. Highlight “Solutions” to get an overview of the total cost. Highlight “Solution 1” to view a breakdown on how the costs are distributed

Tips

After computing a designer study, you will sometimes see results that do not have a good fitness or do not make sense. Below are a few general tips to look at. More information on Darwin Designer can be found in the WaterGEMS Help documentation.

If you are getting strange results, you can try the following: First, make sure you are using the correct design data, including the correct representative design scenario and that scenario includes all pipes to be sized by Darwin Designer. Second, make sure that the representative design scenario runs successfully within Bentley WaterGEMS V8i. If it does not, then Designer will not be able to function correctly. Third, make sure that the correct demands are present. For EPS representative scenarios, make sure your patterns are correct and that you are using the correct time from start value in your design events. Fourth, make sure that you have applied the correct and necessary boundary conditions, including tank levels, pump operation, etc. Fifth, make sure that the range of pipe sizes and rehab actions you are using are reasonable and that you are allowing Darwin Designer a sufficient range of pipe diameters to come up with a reasonable design.  Last, make sure that you have a reasonable number of design and/or rehab groups

Since Darwin Designer applies a competent genetic algorithm to optimize the design, it does not require or have any domain-specific knowledge about the water system. This can have a side-effect for some design cases, like giving up-or-down pipe sizes. In particular, the solutions are evaluated by comparing the fitness values of solutions. Darwin Designer will assume a pipeline with pipe sizes that go up and down (to meet required pressures as closely as possible) is better than one that has a constant size that exceeds the pressures at some locations, since there is no specific penalty assigned to the fitness of a solution that has pipes that change up and down in size. It is up to you to control the eventual design and this can be done by different means.

The first means is simply to make manual adjustments to a design after Darwin Designer has finished. Cleaning up a design may technically move you away from the cheapest design, but an inexpensive design that won't be constructed is of little use. You may find that not much cleaning up is necessary. Quick edits to diameters or rehab actions like can be performed effectively in Darwin Designer by using a manual design run.

Another thing to consider when analyzing a Darwin Designer design is whether the chosen pipe sizes are a function of the lengths of pipe in your model. More information on this can be found in Help under the topic “Advanced Darwin Designer Tips.”

Another means of achieving more constructible designs from Darwin Designer is to group in the same group pipes that would be constructed the same size. For example, a rising main would most likely be constructed a single size, and it would thus make sense to include all the model pipes that make up the rising main in the same design group. What you don't want to do by grouping pipes is artificially design the system even before you have had a chance to optimize it.

When using the optimized designer run, you can change the results simply by changing some of the parameters under the Options tab. For instance, changing the Random Seed to another value will yield different results, possibly a solution that is better than the first pass through the simulation. You can also change items like the penalty factor, probability, and population size. More information on this can be found in Help under the topic “Advanced Darwin Designer Tips.”

WaterGEMS and WaterCAD also come with sample models and lesson files to help with the general setup of a Darwin Designer study. This is a good resource and can allow you to view completed models. The steps for the lesson files can be found in under Help > Quick Start Lessons. The lesson model files are found at the following file path:

C:\Program Files\Bentley\WaterGEMS\Samples\Designer

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

Darwin Scheduler allows you to optimize pump operations. By using genetic algorithm optimization to control nominated pumps during an extended period simulation (EPS), it avoids a manual trial and error approach to finding the most efficient operating schedule. Solutions and costs calculated using Darwin Scheduler can be exported back to the selected scenario.

Background

Previously, the only way to optimize pump operations in a model was to use trial and error, changing settings in the model manually and then computing the model. Darwin Scheduler was introduced with WaterGEMS and WaterCAD V8i, and allows for optimized solutions to be calculated with a genetic algorithm similar to that found in Darwin Calibrator. This tool allows for a more efficient analysis of a model. The optimization only knows the best solution relative to other solution already found during computation. The power of this is in that the study runs through a large number of possible solutions and can often find a very good solution to fit the model.

Darwin Scheduler is used in EPS models only. It is recommended that the model is well-calibrated so that you get the best results.

Darwin Scheduler is included with a license for Bentley WaterGEMS V8. It is also available in Bentley WaterCAD V8 with an additional license configuration. 

Getting Started

Darwin Scheduler is accessed by going to Analysis > Darwin Scheduler, or by clicking the Darwin Scheduler icon above the drawing pane.

Once Darwin Scheduler is open, click the New icon in the upper left select “New Scheduler Study”. An item will appear in the window on the left, and a series of tabs will appear at the top right. Next, choose “New Optimized Run”. A new item will appear below the name of the scheduler study. These can be renamed. In the Scenario tab, choose the scenario that will be optimized.

Next you will need to identify the pumps or pump stations that will be optimized during the Scheduler study, as well as constraints used by the genetic algorithm. Make sure the Scheduler study is highlighted. Select either the “Pumps to Optimize” or “Pump Stations to Optimize” and choose the pumps or pump stations that will be optimized. The preferred usage for Darwin Scheduler is pump stations. In either the “Pumps to Optimize” or “Pump Stations to Optimize” tab, click the New icon. Next, click in the cell for Pump Station or Pump (depending on the usage). Click the ellipsis button (“…”) to activate the Select tool and choose the element you want to add.

In the Constraints tab, the various constraints on the system are entered. These include node pressure, pipe velocity, number of pump starts, and tank levels/elevations. These are the parameters that the solution must satisfy to be viable. This will assure that a solution does not have a very low pressure or empty tank in the results. Note that you have the option to enter overrides for given elements in the system.

The next step is to set the Objective Elements. Darwin Scheduler associates the optimization with an energy pricing pattern. In this section, you can use the icons to add the pumps, variable speed pump batteries, and tanks that will be included in the optimization. Once the pumps are added, you must choose an Energy Pricing pattern for the pump.

If one has not been already created, you can click in the cell and choose the ellipsis button (“…”), which will open the Energy Pricing manager. More information on the Energy Pricing manager can be found in WaterGEMS or WaterCAD Help or the Energy Cost technote also available.

Once the Energy Pricing pattern has been created, you can select it from the pulldown. Note that if all pumps will be using the same pattern, you can also right-click on the column header and choose “Global Edit” to set the patterns for use. In the Tanks tab, the tanks that will be included in the optimization can be selected, but no patterns are associated with them.

Next, select the “Objective Type” tab. There are two choices: Minimum Energy Use and Minimum Energy Cost. Minimum Energy Use will try to minimize the energy used in the system. Minimize Energy Cost uses energy tariffs and peak demand charges to calculate the cost of the energy used in the analysis.

Optimized Run

The next step is to create a new optimized run. Highlight the Scheduler study on the left of the manager and click the New icon. One of the options will be New Optimized Run. This new run can be renamed by clicking the Rename icon or right-clicking on the optimized run and choose Rename.

If you highlight the new optimized run, a new set of tabs will appear on the right side of the manager. This is where you define the parameters specific to this particular optimized run.

The “Pump Stations to Optimize” and “Pumps to Optimize” tabs contain the same information for these two different element types. Each of the pump stations or pumps you identified in your Scheduler study will be displayed. If the pump station or pump is to be included in the optimization, be sure that the item “Include in Optimization?” has a checkmark in it. Next you will need to identify whether the pump is a fixed speed or variable speed pump in the “Decision Type” column. If you choose Fixed Speed, the columns for minimum and maximum speed, as well as the increment, will be unavailable and the pump will be assumed to be set to the relative speed factor you have identified in the pump properties. The pumps are variable speed pumps, you can choose the minimum and maximum speeds that the pump may be able to operate at that allows for the best optimization.

The “Objective Elements” tab allows you to choose if the objective elements identified in the Scheduler study will be available for this particular optimized run.

The Options tab allows you to make adjustments to how Darwin Scheduler will solve for the optimization. Darwin Scheduler uses a genetic algorithm to find the best possible solution. The type of genetic algorithm is select in the Options tab. You can choose the Simple Genetic Algorithm option or the Fast Messy Genetic Algorithm. The Simple Genetic Algorithm will often take less time to compute.

There are a number of other items that can be changed. In most cases, the default settings are sufficient. However, if you make changes to any values here, you could generate a different set of results. For that reason, it is often recommended that you compute several different optimized runs using a different set of options. For instance, in the Genetic Algorithm Options tab, you can select a random seed number. If you enter a different seed number and leave all other parameters that same, you will see a different set of results. Since Darwin Scheduler doesn’t have any optimality and only knows the best solution relative to other solution already found during computation, changing this value could lead to better results.

Once you have set up the parameters, you are ready to compute. Highlight the optimized run on the left side of the manager and select the Compute icon. The computation time will vary depending on the complexity of the model and the setup of the Scheduler study. Once completed, the top solutions will be displayed. The number of solutions is defined in the Options tab.

Understanding the Results and Updating the Model

To review the results from the Scheduler study, highlight the item “Solutions”.

You will see a general overview of the energy cost or energy use results for each of the solutions generated. For details on each solution, choose one of the solutions from the tree. A new set of tabs will appear.

In the “Pump Stations Decisions” and “Pump Decisions” tab, the type of decision is verified (fixed speed or variable speed). By highlighting an individual pump station or pump in the table at the top, information on the speed settings and the number pumps (for pump stations) or lag pumps (for pumps) running are identified.

In the Constraints tab, simulated results for the node pressure, pipe velocity, number pump starts, and tank levels are generated. These are the expected results if the optimization from this solution is exported into the model.

In the Objective Elements tab, a breakdown on the energy cost or energy use for each pump and tank identified in the optimized run will be displayed. These results are based on the energy pricing pattern created for the Scheduler study.

In addition to the numeric results, there are also graphical results that are available. With one of the solutions highlighted, a Graph icon will become active. The graph generated will display the pump speed settings and the number of pumps/lag pumps running for a given solution. You can also generate reports for the solution by choosing the Report icon at the top of the Darwin Scheduler manager.

Running the Scheduler study does not change the properties in the model. After reviewing the results, if you want to export the optimization results into a new scenario in your model, this can also be done in the Darwin Scheduler manager. Choose the solution that you wish to export and choose the Export icon. A new dialog will open that allows you to export the results to a new or existing scenario. It is generally recommended to export to a new scenario so that the original data is not overwritten.

To export to a new scenario, check the “Export Scenario?” box. You can change the default name by simply typing in one in the Name field. By creating a new scenario, new Physical, Active Topology, and Operational alternatives will also be created. You can change the name of these new alternatives as well.

Tips

After computing a Scheduler study, you will sometimes see results that do not have a good fitness or do not make sense. The first thing to check is if the model is well-calibrated. This will have a large effect on the performance of the Scheduler study. WaterGEMS has a calibration tool called Darwin Calibrator that can aid in calibrating a water model.

Making adjustments to the settings in the Options tab is another option. As stated earlier, simply changing the Random Seed number will generate new results after running the study again. You can also make changes to any number of other options. For more information on this, please look at the information in WaterGEMS or WaterCAD Help.

Finally, there is a set of Frequently Asked Questions available in the Help documentation that may prove beneficial. Search Help for “Darwin Scheduler FAQ” to find this information.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

The purpose of this technote is to discuss the Pipe Renewal Planner feature available in the Bentley WaterGEMS V8i Select Series 2. Additional information can be found in the WaterGEMS Help menu.

Background

It is often advantageous to know about vulnerable parts of a system so that potential problems can be fixed before they cause system disruptions. Pipe Renewal Planner provides the user with a method to calculate a weighted score for each pipe based on user-defined aspects of the model.

Pipe Renewal Planner can give the user guidance to determine which pipes in the model may be most vulnerable and allow them to remedy issues that have caused the pipe to have a high score.

This is a new feature included with WaterGEMS V8i Select Series 2 (build 08.11.02.31) or later. It is available as a licensing add-on for WaterCAD V8i Select Series 2.

Before using Pipe Renewal Planner

Pipe Renewal Planner provides the user with a method to calculate a weighted score for each pipe based on user-defined aspects of the model. Pipe Renewal Planner can include any aspect that can be entered for a pipe or calculated for the pipe. These include capacity, projected pipe breaks, material, and depth of cover, among others. Scores determined by Pipe Renewal Planner are highly dependent on the specific system and on the availability of data.

Before using Pipe Renewal Planner, the user needs to identify which aspects will be used in scoring pipes and which properties are going to be used as a basis for calculating the aspect scores. It may be necessary to define new properties in User Data Extensions and import values for properties from external data sources using ModelBuilder or copy/paste features. In order to import values, it is essential that there exist a common key field shared by the WaterCAD V8i model and the external data source.

Calculation of raw scores for aspects such as capacity (fire flow) and criticality (shortfall) can be time consuming such that it may be advisable to have already computed these analyses before computing Pipe Renewal Planner. However, if any properties are changed that may affect scores, it is possible to recompute the scenario from within Pipe Renewal Planner.

Also keep in mind that doing the default Pipe Renewal Planner analysis will use fire flow (capacity) results, criticality and segmentation analysis, and pipe break analysis. It is recommended that this is reviewed beforehand, as this technote will only touch on these in general terms. Please review the available technotes or Help items on these features for more information.

Using Pipe Renewal Planner

You can access Pipe Renewal Planner by selecting Analysis > Pipe Renewal Planner or picking the Pipe Renewal Planner icon from the toolbar.

This opens the welcome dialog if no analyses have already been run.

To start a new analysis, click the New icon in the upper left. A new pipe renewal planner label will appear in the list on the left, while the section to the right will be populated with default aspects: pipe break, criticality, and capacity (fire flow).

Each aspect has a select number of properties associated with them. The Selection Set column allows you to choose either the entire network or a predefined selection set of elements for the aspect analysis. The Weight column is a way for you to decide how much emphasis will be placed on a certain aspect in Pipe Renewal Planner. The Scenario column defines which scenario the data for the individual aspect comes from. These different scenarios can be computed ahead of time, which will save some computational time for the Pipe Renewal Planner analysis itself. Computing the scenario ahead of time will also allow you to verify that the results for the aspects are reasonable. However, if you have not computed the scenario, you can put a checkmark in the Compute Scenario column and Pipe Renewal Planner will compute the scenario during the analysis.

In addition to the default aspects, you can also add new aspects for the pipe renewal planner to account for. To do this, either click the New icon below the General tab or simply click in the empty cell beneath the default aspects. Then click in the cell and select the ellipsis button.

This will open the Aspects manager. Select the New icon to create a selection. Then select which property you would like to be considered in the analysis.

Whether you use the default aspects or create new ones, you will need to select the Representative Scenario for the analysis. This does not need to be the current scenario. The representative scenario will be used as the source of element properties and the location to save results except where another scenario is explicitly called out.

Note: Two Pipe Renewal Planner configurations cannot share the same representative scenario. If a scenario is selected, it is not available as the representative scenario from the pulldown menu for other Pipe Renewal Planner configurations.

Computing and Viewing Results

The individual aspects will need to be set up before computing the Pipe Renewal Planner analysis. For information on how run a fire flow analysis, a criticality and segmentation analysis, and a pipe break analysis, please review posted information in Help or in the technotes found in the Hydraulics and Hydrology Technotes page.

Note: the raw score for capacity (fire flow) for a given pipe is equal to the difference between the "target" velocity (the "Pipe velocity greater than" field in the fire flow alternative) and the maximum velocity in that pipe (over all the fire flow events). In order for a pipe to be considered during this part of the calculation, it must either be adjacent to a fire flow node or be included in the "auxiliary output selection set" in the fire flow alternative.

Once you have your aspects selected and applied, you will be ready to compute Pipe Renewal Planner. Click the green Compute icon in the Pipe Renewal Planner manager.

Note: If you have not computed the scenarios associated with the aspects, you will be prompted to do so. You can either compute the scenarios individually or put a checkmark in the Compute Scenario column for the different aspects.

If you click the Results tab, you will see the results of the analysis.

The overall score for the pipe is found in the Pipe Score column. It is the weighted sum of the individual aspect scores. A higher value indicates a pipe with potential problems in need of repair, rehabilitation, replacement or some other remedial action. Scores are presented on a 0 to 100 scale unless the user has set up some different scaling.

Other data included in the results tab include the scores and results for the individual aspects. The data can be sorted by right-clicking on a column header and choosing the Sort function. By choosing “Sort Descending,” the highest score will be at the top.

You can also view the data graphically in the drawing pane by setting up color coding in the Element Symbology manager. Open this by clicking View > Element Symbology. Right-click on Pipe and select New > Color Coding. This will open a new manager.

Choose “Pipe Score” from the Properties pulldown and select the range. You can initialize the color coding on the right side of the manager. More information on color coding can be found under Help.

See Also

Understanding Automated Fire Flow Results

Running a Criticality Analysis

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]  

External Links

Water and Wastewater Forums

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

The Network Navigator consists of a toolbar and a table that lists the Label and ID of each of the elements contained within the current selection. Predefined queries can help you select certain queries with an ease without spending too much time.   

To open the Network Navigator, click the View menu and select the Network Navigator command, press , or click the Network Navigator button on the View toolbar.

Physical Overview of Network Navigator

Predefined Queries

The Network Navigator provides access to a number of predefined queries grouped categorically, accessed by clicking the [>] button. Categories and the queries contained therein include

Network

Network queries include "All Elements" queries for each element type, allowing you to display all elements of any type in the Network Navigator. 

Network Review 

Network Review Queries include the following:

Nodes In Close Proximity - Identifies nodes within a specific tolerance.
Crossing Pipes - Identifies pipes that intersect one another with no junction at the intersection.
Orphaned Nodes - Identifies nodes that are not connected to a pipe in the model.
Orphaned Isolation Valves - Identifies isolation valves that are not connected to a pipe in the model.
Dead End Nodes - Identifies nodes that are only connected to one pipe.
Dead End Junctions - Identifies junctions that are only connected to one pipe.
Pipe Split Candidates- Identifies nodes near a pipe that may be intended to be nodes along the pipe. The tolerance value can be set for the maximum distance from the pipe where the node should be considered as a pipe split candidate.
Pipes Missing Nodes - Identifies which pipes are missing either one or both end nodes.
Duplicate Pipes - Identifies instances in the model where a pipe shares both end nodes with another pipe.

Network Trace

Network Trace Queries include the following:

Find Connected - Locates all the connected elements to the selected element in the network.
Find Adjacent Nodes - Locates all node elements connected upstream or downstream of the selected element or elements.
Find Adjacent Links - Locates all link elements connected upstream or downstream of the selected element or elements.
Find Disconnected - Locates all the disconnected elements in the network by reporting all the elements not connected to the selected element.
Find Shortest Path - Select a Start Node and a Stop Node. The query reports the shortest path between the two nodes based upon the shortest number of edges.
Trace Upstream - Locates all the elements connected upstream of the selected downstream element.
Trace Downstream - Locates all the elements connected downstream of the selected upstream element.
Isolate - Select an element that needs to be serviced. Run the query to locate the nearest isolation valves. In order to service the element, this will identify where shut off points and isolation valves are located.
Find Initially Isolated Elements - Locates elements that are not connected or cannot be reached from any boundary condition.

Input

Input Queries include a number of queries that allow you to find elements that satisfy various conditions based on input data specified for them. Input queries include:

Duplicate Labels - Locates duplicate labels according to parameters set by the user. See Using the Duplicate Labels Query for more information.
Elements With SCADA Data - Locates elements that are have SCADA data associated with them.
Inactive Elements - Locates elements that have been set to Inactive.
Pipes with Check Valves - Locates pipes that have the Has Check Valve? input attribute set to True.
Controlled Elements - Locates all elements that are referenced in a control Action.
Controlled Pumps - Locates all pumps that are referenced in a control Action.
Controlled Valves - Locates all valves that are referenced in a control Action.
Controlled Pipes - Locates all pipes that are referenced in a control Action.
Controlling Elements - Locates all elements that are referenced in a control Condition.
Initially Off Pumps - Locates all pumps whose Status (Initial) input attribute is set to Off.
Initially Closed Control Valves - Locates all control valves whose Status (Initial) input attribute is set to Closed.
Initially Inactive Control Valves - Locates all control valves whose Status (Initial) input attribute is set to Inactive.
Initially Closed Pipes - Locates all pipes whose Status (Initial) input attribute is set to Closed.
Fire Flow Nodes - Locates nodes included in the group of elements specified in the Fire Flow Alternative's Fire Flow Nodes field.
Constituent Source Nodes - Locates all nodes whose Is Constituent Source? input attribute is set to True.
Nodes with Non-Zero Initial Constituent Concentration - Locates all nodes whose Concentration (Initial) input attribute value is something other than zero.
Tanks with Local Bulk Reaction Rate Coefficient - Locates all tanks whose Specify Local Bulk Rate? input attribute is set to True.
Pipes with Local Reaction Rate Coefficients - Locates all pipes whose Specify Local Bulk Reaction Rate? input attribute is set to True.
Pipes with Hyperlinks - Locates all pipes that have one or more associated hyperlinks.
Nodes with Hyperlinks - Locates all nodes that have one or more associated hyperlinks.

Results

Results Queries include a number of queries that allow you to find elements that satisfy various conditions based on output results calculated for them. Results queries include:

Negative Pressures - Locates all nodes that have negative calculated pressure results.
Pumps Operating Out of Range - Locates all pumps whose Pump Exceeds Operating Range? result attribute displays True.
Pumps Cannot Deliver Flow or Head - Locates all pumps whose Cannot Deliver Flow or Head? result attribute displays True.
Valves Cannot Deliver Flow or Head - Locates all valves whose Cannot Deliver Flow or Head? result attribute displays True.
Empty Tanks - Locates all tanks whose Status (Calculated) result attribute displays Empty.
Full Tanks - Locates all tanks whose Status (Calculated) result attribute displays Full.
Off Pumps - Locates all pumps whose Status (Calculated) result attribute displays Off.
Closed Control Valves - Locates all control valves whose Status (Calculated) result attribute displays Closed.
Inactive Control Valves - Locates all control valves whose Status (Calculated) result attribute displays Inactive.
Closed Pipes - Locates all pipes whose Status (Calculated) result attribute displays Closed.
Failed Fire Flow Constraints - Locates all elements whose Satisfies Fire Flow Constraints? result attribute displays False.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]  

External Links

Water and Wastewater Forums

Bentley Technical Support KnowledgeBase

Bentley LEARN Server