Create Watersheds Using InfoSWMM Subcatchment Manager

Subject:  Create Watersheds Using InfoSWMM Subcatchment Manager

  

The Subcatchment Manager of InfoSWMM will  help calculate most of the  physical parameters associated with a Watershed or Subcatchment in SWMM 5 from a Digital Elevation Data (Step 1).  The Subcatchments area created from a Flow Direction Raster (Step 2) and a Flow Accumulation Raster (Step 4) after filling in any Sinks in the DEM (Step 3).  The created watersheds (Step 5).   The physical parameters estimated from the DEM are shown in Figure 1.

Figure 1.  Physical Data Estimated from a DEM using the Subcatchment Manager in InfoSWMM.

Step 1.  Find, Create or Otherwise Locate a TIN, DEM or DTM for the project area with elevation data that you can  use with the InfoSWMM Subcatchment Manager.

Step 2.   Create a Flow Direction Raster using the Watershed Command.

Step 3.   Check to see if there are Sinks in the Elevation Data that have to be filled using the Filled Sink Command.

Step 4.   Create a Flow Accumulation Raster

Step 5.   Create the Watersheds from the Flow Direction and Flow Accumulation Rasters.

Three Flow Divider Link Example in SWMM 5

Subject:  Three Flow Divider Link Example in SWMM 5

You can have more than 2 downstream OUTLET Type links in the SWMM 5 dynamic wave solution.  Each link, Under5, Over5 and ReturnFlow is an OUTLET Link with a rating curve depth/flow table.  Depending on the depth in the storage node DIVIDER, the flow is computed from the table for links Under5, Over5 and ReturnFlow.

Output Statstics Manager to find negative flows in InfoSWMM

Subject:  Output Statstics Manager to find negative flows in InfoSWMM

Output Statstics Manager to find negative flows with these parameters:

1.       Pipe Features
2.       Use a Domain with your force mains
3.       Select Flow
4.       Event Dependent
5.       Total – NOT Mean or Peak to  find the negative and positive flows
6.       Large NEGATIVE Flow Threshold
7.       Large NEGATIVE Volume Threshold
8.       Zero for Interevent Time to pick up all values
9.       You will get a table that shows you the minimun flows, and a histogram of the flows

Drawing features to show multiple attributes in InfoSWMM and InfoSewer

Subject:   Drawing features to show multiple attributes in InfoSWMM

Your network data usually has a number of different attributes that describe the features it represents (Figure 3). While you'll commonly use one of the attributes to symbolize the

data—for example, showing one quantity in the InfoSWMM Map Display —you may sometimes want to use more than one.   One way to show multiple attributes inInfoSWMM is to copy layers and then use the Layer Properties to color, map or otherwise display the multivariable data (Figure 1).  For example, Figure 2 shows the important Subcatchment parameters of Slope, Imperviousness and Width as graduated colors, dots and a pie shape, respectively.

Figure 1.  Use the Symbology Tab to select the attribute you want to show and the way to show the attribute.

Figure 2.   The Subcatchment slope is shown in graduated colors, the percent impervious in scattered dots a a measels map and the Subcatchment Width is shown in a pie graph with the size of the pie a function  of the total  width.

Figure 3.  Physical Data Estimated from a DEM using the Subcatchment Manager in InfoSWMM.

Flow Dividers in SWMM 5 Dynamic Routing

Note:  Flow Dividers in SWMM 5 Dynamic Routing

You can  have flow dividers in SWMM 5 dynamic routing by using Storage Nodes for the dividers, OUTLET links for the downstream links and minimizing downstream HGL effects. The needed components are:

1.   A Storage Node for the divider node as a OUTLET Link does not have a Surface Area,
2.   Two or More OUTLET Links as the downstream diversion and cutoff links,
3.   Two or More Rating Curves to divide the flow up based on either depth or head,
4.   Pumps, Outfalls or Steep Sloped Links Downstream of the diversion and cutoff links to minimize downstream HGL  effects

The Keep and Dampen options and their effect on the four main terms of the St Venant equation in SWMM5

Note:  The Keep and Dampen options and their effect on the four main terms of the St Venant equation. 

The four terms are are used in the new flow for a time step of Qnew:

Qnew = (Qold – dq2 + dq3 + dq4) / ( 1 + dq1)

when the force main or gravity main is full dq3 and dq4 are zero and  Qnew = (Qold – dq2) / ( 1 + dq1)

The dq4 term in dynamic.c uses the area upstream (a1) and area downstream (a2), the midpoint velocity, the sigma factor (a function of the link Froude number), the link length and the time step or

dq4 = Time Step * Velocity * Velocity * (a2 – a1) / Link Length * Sigma

where Sigma is a function of the Froude Number and the Keep, Dampen and Ignore Inertial Term Options.  Keep sets Sigma to 1 always and Dampen set Sigma based on the Froude number, Ignore sets Sigma to 0 all  of the time during the simulation

the dq3 term in dynamic.c uses the current midpoint area (a function of the midpoint depth), the sigma factor and the midpoint velocity.

dq3 = 2 * Velocity * ( Amid(current iteration) – Amid (last time step) * Sigma

dq1 = Time Step * RoughFactor / Rwtd^1.333 * |Velocity|

The weighted area (Awtd) is used in the dq2 term of the St. Venant equation:

dq2 = Time Step * Awtd * (Head Downstream – Head Upstream) / Link Length or

dq2 = Time Step * Awtd * (Head Downstream – Head Upstream) / Link Length

Normally, dq1 (Friction Loss / Maroon in the Graph) balances dq2 (Water Surface Slope Term or Green in the Graph) but often for links with a large difference between upstream and  downstream depths dq4 (Red in the Graph) can have a significant value.  If dq4 or dq3 are important then the depth of water to increases to pass the same flow using the Keep option over the Ignore.   If you have a link with a Froude number near or over 1.0 (Supercritical) then using Keep or Dampen  for the Options may result in depth differences.   The effect of Keep is to increase the "loss" terms in the St VenantEquation.   The effect of Dampen and Ignore is to decrease the sum of the "loss" terms in the St. Venant Solution and lower the simulated depth.

Surcharged Node and the Link Connection in SWMM 5

Subject:   Surcharged Node and the Link Connection in SWMM 5

A surcharged node in SWMM 5 uses this point iteration equation (Figure 1):

dY/dt = dQ / The sum of the Connecting Link values of  dQ/dH

where Y is the depth in the node, dt is the time step, H is the head across the link (downstream – upstream), dQ is the net inflow into the node and dQ/dHis the derivative with respect to H of the link  St Venant equation.  If you are trying to calibrate the surcharged node depth, the main calibration variables are the time step and the link  roughness:

1.   Mannings's N
2.   Hazen-Williams or
3.   Darcy-Weisbach 

The link roughness is part of the term dq1 in the St Venant solution and the other loss terms are included in the term dq5.  You can adjust the roughness of the surcharged link  to affect the node surcharge depth.

Figure 1.  The Node Surcharge Equation is a function of the net inflow and the sum of the term dQ/dH in all connecting links. Generally, as you increase the roughness the value of dQ/dH increases and the denominator of the term dY/dt = dQ/dQdH increases. 

Figure 2.  The value of dQ/dH in a link as the roughness of the link increases.

How to Divide the Inflow at a Node in InfoSWMM

Subject:  How to Divide the Inflow at a Node in InfoSWMM

In SWMM 5 only the Kinematic Wave solution allows a flow divider at a node to divide the Inflow to node to two  downstream  links, but you can use the Inflow/Outflow Outlet type in InfoSWMM to divide the inflow based on a Inflow/Outflow Diversion Table (Figure 1).  For example, in InfoSWMM it is possible to have two downstream links from a Node that are Outlet types Inflow/Outflow so that the low flow goes down one link and the high flow goes down the other link (Figure 2 and Figure 3).   The low flow and the high flow  link  use different diversion tables in which the tables are constructed so that the flow is positive in one link and zero in the other to a dividing flow value and then zero and positive for the same two links after the dividing flow value ( 5 cfs in the example).

Figure 1.  Types of OUTLETS in InfoSWMM and SWMM 5

Figure 2.  Example low flow and high flow Outlet Links to divide the total  inflow at the upstream node at 5 cfs.

Figure 3.   The flow is divided into the low and high flow links at the dividing flow of 5 cfs.

Example SWMM 5 Model for Activated Slude

Note:   Example SWMM 5 Model for Activated Sludge

Here is one example of how to model an activated sludge tank.  The image is Wikipedia (http://en.wikipedia.org/wiki/Activated_sludge)  and is the watermark background in the SWMM 5 GUI.  There is 100 lps inflow, 20 percent recycle and 10 percent sludge drawoff.   You can adjust the amount of recycle and sludge altering the pump type 2 flows or if you want to increase the inflows – add more flow in the RawWater inflow node.

How to Make Icons and Expand the Toolbars in InfoSWMM and InfoSewer

Subject:  How to Make Icons and Expand the Toolbars in InfoSWMM and InfoSewer

You can customize the toolbars in InfoSWMM and InfoSewer by clicking on Customize and performing 4 steps:

Step 1.  Click on Customize

Step 2.  Move the tool from the Command list to the toolbar.

Step 3.  Change the Button Image for the Default Style.

Step 4.  The Toolbar now has a new Icon for the InfoSWMM command.

Step 1.  Click on Customize

Step 2.  Move the tool from the Command list to the toolbar.

Step 3.  Change the Button Image for the Default Style.

Step 4.  The Toolbar now has a new Icon for the InfoSWMM command.

Example Dual Drainage SWMM 5 model

 Example Dual Drainage SWMM 5 model

How to Edit the Subcatchment Polygons in InfoSWMM with Arc Map

Subject:  How to Edit the Subcatchment Polygons in InfoSWMM with Arc Map

You can edit the polygon boundaries of the Subcatchments in Arc GIS by using the Editor command and either editing the vertices or by using the Reshape Feature Tool to adjust the boundaries or snap to the polygon lines or vertex points.    You should start the editing session by right mouse clickining on the Subcatchment Feature layer

Vertex Editing and Reshape Feature Tool

 

The Pump summary table of SWMM5.0.022 and the Percent Time off Columns

Subject:  The Pump summary table of SWMM5.0.022 and the Percent Time off Columns

The pump summary table at the end of the SWMM 5 report file has two columns for the time off the pump curve BUT the two columns are only informative if the pump is a type 4pump.  If the pump type is 1, 2 or 3 then the low column is always 0 and when the volume, depth or head is either below the lowest point in the point curve or above the highest point in the pump curve the pump summary table lists the time off either low or high in the High column.

xMin is  the 1^st point in the pump curve for either volume, depth, head or depth, respectively for pump1, pump2, pump3 and pump4 type pumps

xMax is the last point in the pump curve for either volume, depth, head or depth, respectively for pump1, pump2, pump3 and pump4 type pumps

Average Residence time in InfoSWMM and H2OMAP SWMM

Subject:  Average Residence time in InfoSWMM and H2OMAP SWMM

Here is one way to estimate the residence time:

1.       Plot the System Outflow and Storage in the InfoSWMM Report Manager

2.       Click on the Report Button and copy the Outflow and Storage Time Series

3.       Paste to  Excel

4.       Calculate the Residence time as Storage / Outflow and Graph

5.       You will have an understanding of the residence time in your network

6.       If you have a dry weather flow then a hot start file will give a better estimate at the start of the simulation 

An Example of the Importance of the Term DQ4 in the SWMM 5 St Venant Solution

Subject:   An Example of the Importance of the Term DQ4 in the SWMM 5 St Venant Solution

The four terms are are used in the new flow for a time step of Qnew:

Qnew = (Qold – dq2 + dq3 + dq4) / ( 1 + dq1)

when the force main or gravity main is full dq3 and dq4 are zero and  Qnew = (Qold – dq2) / ( 1 + dq1)

The dq4 term in dynamic.c uses the area upstream (a1) and area downstream (a2), the midpoint velocity, the sigma factor (a function of the link Froude number), the link length and the time step or

dq4 = Time Step * Velocity * Velocity * (a2 – a1) / Link Length * Sigma

where Sigma is a function of the Froude Number and the Keep, Dampen and Ignore Inertial Term Options.  Keep sets Sigma to 1 always and Dampen set Sigma based on the Froude number, Ignore sets Sigma to 0 all  of the time during the simulation.

The value of dq4 increases when there is a significant difference in the cross sectional  area of the downstream end of the link and the upstream end of the link.  In this  example, the downstream storage node causes a backflow in the link.   The flow may look unstable in the link  flow time series but the change in flow is simply due to the water sloshing back and forth.  There is not continuity error as the term dq4 keeps the water in the link  in balance.

Use the SWMM 5 Scatter Graph to show the Pump Curve used during the Simulation

Subject:  Use the SWMM 5 Scatter Graph to show the Pump Curve used during the Simulation

You can use a scatter graph to show the relationship between the pump during the simulation and the Storage Depth.   If the pump is on the curve based on the pump summary table then the scatter graph should  look like the pump curve.  The pump summary table in the  SWMM 5 RPT also shows you the time off the pump curve low and high. 

How to Import the SWMM 5 Report File as a Layer in infoSWMM

Subject:  How to Import the SWMM 5 Report File as a Layer in infoSWMM

The idea of this blog of note is to show how one may extract information from the SWMM 5 or InfoSWMM RPT file and import the Excel  File as a feature in InfoSWMM.  This blog has an example Excel file to illustrate the linkage. The steps are:

Step 1:  Copy the whole row  from Conduit Summary from the InfoSWMM Browser

Step 2:  Add the two columns length and  slope from the Link Summary Table and the InfoSWMM Browser

Step 3:  You need a few calculations based on the table values from SWMM 5 to estimate the CFL  time steps in the .

Step 4:   Add the Excel Spreadsheet as a layer in InfoSWMM – the Named Range should be added to insure valid numbers and not Nulls after the join

Step 5:  You can now plot the CFL Time Step for the Links using the Layer Properties command in Arc Map

  

Step 1:  Copy the whole row  from Conduit Summary

Step 2:  Add the two columns length and  slope from the Link Summary Table

Step 3:  You need a few calculations based on the table values from SWMM 5 to estimate the CFL  time steps.

The CFL Step      = Length / (Full  Velocity + (Gravity * Full Depth)^0.5)

Full Velocity        = Full Flow / Full  Area

You also need to create a Name A Range for you data so that the data does not show up as Nulls

Step 4:  Add the Excel Spreadsheet as a layer in InfoSWMM – the Named Range should be added

Step 4:  Join the Excel  Table to the InfoSWMM Conduit Feature Layer

Step 5:  You can now plot the CFL Time Step for the Links using the Layer Properties command in Arc Map

How to Approximate a Timer in the RTC Rules of SWMM 5

Subject:   How to Approximate a Timer in the RTC Rules of SWMM 5

SWMM 5 does not have a explicit timer in its Real Time Control (RTC) rules but you can approximate it by using a Control Curve as in the attached example model.  The Control Curve will modify the setting of the Weir by the Inflow to the Storage node.  You can have normal weir flow settings based on the invert elevation of the weir and the Surface node water surface elevation but in addition you can control the weir setting by:

1.   Closing the weir when the inflow is low,
2.   Closing the weir by staggered Storage node depth,
3.   Opening the weir gradually when the inflow increases
4.   Closing the weir by a combination of Node Depth IF statements and Control Curve rules

For example, you can have the Weir Setting controlled the Node Depth,  Link Inflow and Node Inflow  simultaneously approximately with the depth and the inflow parameters closing the weir by proxy instead of by time since the closing.

The Importance of Viewing Results at the Proper Time Scale in SWMM5 and InfoSWMM Models

Subject:   The Importance of Viewing Results at the Proper Time Scale

In SWMM 5 when you are simulating rapidly changing flow – such as pump flows – it is important to  remember that you are only seeing the results of the simulation at your selected report time step.  Here is an example model with the same number of pump starts for all three simulations (318), the same  average time step during the simulation (10 seconds) but different report time steps.  The conception of the pump starts is totally different visually depending on the selected report time steps.  You should always compare the starts using the pump graphs and the pump summary table.    The percent utilized and the number of pump start ups tells you  the mean pump start length or in this case 153 seconds or 45.1 percent of 30 hours divided by 318 pump starts.

How to Make a Smaller Model out of a Large Model in InfoSWMM

Subject:   How to Make a Smaller Model out of a Large Model in InfoSWMM

InfoSWMM and H2OMAP SWMM will export only those ACTIVE elements to SWMM 5 as defined by the Facility Manager. 

You can use to feature to make smaller SWMM 5 models and then reimport the exported smaller SWMM 5 model back into a H2OMAP SWMM or InfoSWMM scenario.

How to Copy from a SWMM 5 Table to Excel

Subject:  How to Copy from a SWMM 5 Table to Excel 

Step 1. Highlight the rows you want to copy to Excel 

Step 2:  Use the Copy to Clipboard or Copy to File command 

Step 3:  Paste in Excel or open the exported text file  

How to Make a SWMM 5 Calibration File from InfoSWMM

Subject:  How to Make a SWMM 5 Calibration File from InfoSWMM 

1^st Step:  Graph a Link  in InfoSWMM using the Date /Time Format

2^nd Step:  Click on the Report Button and copy the 1^st two columns of data

3^rd Step:  Save the  copied columns to a data file, replace the semi colon and add the name of the link  to the top of the data file as shown below

4^th Step:  Connect the created calibration data file t o the SWMM 5 Calibration Data Link Flow Rate

5^th Step:  Run the  Simulation and you should see two  graphs on the screen for the designated link