High and Low Estimates of InfoSWMM/ICM Subcatchment Dimension for SWMM Hydrology

High and Low Estimates of InfoSWMM/ICM Subcatchment Dimension for SWMM Hydrology

These are the estimates for both SWMM 5, InfoSWMM and ICM SWMM Hydrology, the low estimate is 0.2*SQRT(Area in Feet) and the High Estimate is 5*SQRT(Area in Feet), Figure 1.  You can use higher or lower numbers to calibrate to monitored data but these are just guidelines using the InfoSWMM Subcatchment Manager Width Tool (Figure 2).

Table 1.  High and Low Estimates of the ICM Subcatchment Dimension for SWMM Hydrology or the SWMM 5 Subcatchment Width.

Subcatchment Area  (Acres)	Low Estimate  Width (Feet), W = 0.2*SQRT(Area)	High Estimate  Width (Feet), W =5*SQRT(Area)
1	41.74	1,043.55
5	93.34	2,333.45
10	132	3,300.00
25	208.71	5,217.76
50	295.16	7,379.02
100	417.42	10,435.52
200	590.32	14,758.05
300	722.99	18,074.84
400	834.84	20,871.03
500	933.38	23,334.52
600	1022.47	25,561.69
700	1104.39	27,609.78
800	1180.64	29,516.10
900	1252.26	31,306.55
1,000	1320	33,000.00
5,000	2951.61	73,790.24
10,000	4174.21	104,355.16
50,000	9333.81	233,345.24
100,000	13200	330,000.00

Figure 1  InfoSWMM Subcatchment Manager Width Estimator.

How do V-notch weirs work in SWMM 5?

How do V-notch weirs work in SWMM 5?

Hi Keith, As you change the Length which is actually the Top Width you change the area and hydraulic radius of the Weir. 

The height of a V-Notch weir is the Height Value in the SWMM 5 Weir Property Dialog (Figure 1) 

The Length in the Dialog for a V-Notch is the Top Width of Triangular Shaped V-Notch Weir. 

The slope of the sides of the V-Notch Weir is Square Root (1 + Top Width / Height / 2 * Top Width / Height / 2)

The full area is the Height * Height * Side Slope

The hydraulic radius is the Height / ( 2 * Height * Side Slope)

The two values Height and Length for a SWMM 5 V-Notch Weir determines the area, hydraulic radius and side slope of the weir.

Figure 1.   Parameters for a V-Notch Weir in SWMM 5

How to Import Subcatchments from GIS into InfoSWMM

How to Import Subcatchments from GIS into InfoSWMM

Step 1:  Add your shapefile using  the Add Data command.

Step 2:  Your imported shape file has no subcatchment data before we initialize the project.

Step 3:  Add your subcatchment data using the GIS Exchange Cluster Import

Step 4:  Now you have the Subcatchments in the DB Tables and can now calculate the area.

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Step 1:  Add your shapefile using  the Add Data command.

Step 2:  Your imported shape file has no subcatchment data

Step 3:  Add your subcatchment data using the GIS Exchange Cluster Import

  

Step 4:  Now you have the Subcatchments in the DB Tables and can now calculate the area.

We still have to enter 1/10000 to get the right units for subcatchment area using the Auto Area Calculation under Tools preferences.  You first import the shape file and then you turn on Auto Area Calculation, enter a value for the Area Scaling Factor and then use the tool Utilities, Update DB from Map, All Subcatchment to get the Subcatchment Area in hectares.

How are Flooded Time, Surcharged Time and Flooded Volume Calculated in InfoSWMM and H2OMAP SWMM?

How are Flooded Time, Surcharged Time and Flooded Volume Calculated in InfoSWMM and H2OMAP SWMM?

The time, volume and flooded rate shown in the InfoSWMM and H2OMAP SWMM Report File Node Flooding Summary (Figure 2) are calculated as follows (Figure 1):

For All Nodes NOT Outfalls ( this includes Junctions, Storage Nodes, Dividers)

If the New Volume is greater than the Full Volume of the or there is Overflow then at each time step the Time Flooded is increased

If the New Volume is greater than the Full Volume of the or there is Overflow then at each time step the Volume Flooded is increased by the Overflow *Time Step

If the New Volume is greater than the Full Volume of the or there is Overflow AND Surface Ponding is Used then the Ponded Volume is New Volume – Full Volume

If the Node Depth Plus the Node Invert Elevation is above the Node Crown Elevation then at each time step the time surcharged is increased.   The InfoSWMM andH2OMAP SWMM Map Display variables should be FLOOD_VOLM for the No Surface Ponding option (Figure 3) and PONDED_VOL if you are using the Global Surface Ponding Option (Figure 4).

Figure 1.  Levels of Surcharged and Flooding in SWMM 5.

Figure 2.  SWMM 5 Node Flooding Summary or the InfoSWMM and H2OMAP SWMM HTML Report file.

Figure 3.  The Map Display of the Node Flooding using the No Surface Ponding Option should use the Map Display Variable FLOOD_VOLM

Figure 4.  The Map Display of the Node Flooding using the Surface Ponding Option should use the Map Display Variable PONDED_VOL which shows the Maximum Stored Pond Volume.

Inflow Time Series in InfoSewer

This is how InfoSewer can use a time series of inflow at a specific node:

1.       Use a mean loading of 1 so that the values in the Inflow Time Series stay the same as your inflow units in InfoSewer (Figure 1)

Figure 1.   Load with a Pattern of Inflow will create a loading to the node based on your inflow time series.

2.      Create a PATTERN that is equal to your inflow time series
3.      The pattern has to have the same time steps as your default Run Manager Pattern option, normally this will  be one hour
4.      The factor column is your inflow in cfs, gpm, lps or mgd (Figure 2)

Figure 2.  The Inflow Time Series Pattern is your Flow

5.      The Base Load should equal your Inflow Pattern (Figure 3)

Figure 3.  Base Flow from the Inflow Time Series Pattern

How to Use the Map Display for the Maximum Adjusted d/D or Maximum q/Q in an EPS InfoSewer Simulation

How to Use the Map Display for the Maximum Adjusted d/D  or Maximum q/Q in an EPS InfoSewer Simulation

You can do a Map Display of the adjusted d/D values (Figure 1)  from the Gravity Main Range Report (Figure 2) to show those pipes that are full thematically.  For example, the links in red in Figure 1 show the effect of the pump blockage and the links in green are those NOT full due to the pump blockage.  You will need to copy the adjusted d/D or the maximum q/Q values from the Range report to the Link Information Table to have some values to Map (Figure 3 and 4).   The maximum adjusted d/D or the Maximum q/Q can be mapped using the new link information (Figure 5).

Figure 1  Map Display of the Maximum Adjusted d/D from the Gravity Range Report.

Figure 2.   Maximum Adjusted d/D or Maximum q/Q can be copied from the EPS Range Gravity Main Report.

Figure 3.  Create a new variable In the Link Information Table.

Figure 4.  New variables for the Map Display from the Range Report in the Pipe Information Tables for Each Link.

Figure 5.  Link Information new Parameters of Variables can be used to Display the maximum d/D or q/Q during the EPS simulation.

LID and BMP Modeling in InfoSWMM and H20Map SWMM

Subject:   LID and BMP Modelling in InfoSWMM and H20Map SWMM

The attached PDF file describes some of the Low Impact Modeling and Best Management Practice modeling options in InfoSWMM and H2OMap SWMM (Figure 1)

Low Impact Development (LID)                                                           Page 3

Low Impact Development (LID)                                                           Page 4

LID Controls and Connection to the Subcatchments                          Page 5

Simulation Options for LID's                                                                 Page 6

Water Quality Features                                                                         Page 7

External Loading Buildup                                                                    Page 8

Simulation Options for Quality                                                            Page 9

Buildup/Washoff Options                                                                    Page 10

LID's are Unlimited Per Subcatchment                                            Page 11

Map Display of the Number of Units per Subcatchment                Page 12

LID Controls in DB Tables                                                                   Page 13

LID Layers                                                                                            Page 14

LID Storage Layer                                                                               Page 15

LID Process Components Page                                                            Page 16

LID Processes                                                                                     Page 17

LID Usage in DB Tables                                                                      Page 18

LID Usage at the Subcatchments                                                        Page 19

Rain Barrel LID                                                                                   Page 20

Swale LID                                                                                          Page 21

Components Per Subcatchment                                                          Page 22

LID Report Variables                                                                           Page 23

LID Report Text File                                                                            Page 24

LID Summary Report                                                                          Page 25

LID Report at a Time Step                                                                   Page 26

LID Graphs by Subcatchment                                                              Page 27

LID Import and Export to SWMM                                                         Page 28

Figure 1.  LID Options include on a Subcatchment include Rain Barrels, Bio-Retention Cells, Infiltration Trench, Porous Pavement and Vegetative Swales

Download PDF File 

Steps in Using RDII Analyst for InfoSWMM, ICM and InfoSewer

Subject:  Steps in Using RDII Analyst for InfoSWMM, ICM and InfoSewer

Step 1: Create a Base UH  in the Operation Tab of the Attribute Browser using RDII Analyst (Figure 1)

Step 2: Assign a UH to at Least 1 Node Using the Inflow Icon  

Step 3: Open Up RDII Analyst and Click on New to Create a RDII Session    

Step 4: Define the Flow and Rainfall File     

Step 5: Review the Imported Flow Time Series Step 6: Review the Imported Rainfall  Time Series          

Step 7: Units and RDII Analyst Dates are Controlled by the Simulation Manager   

Step 8: Extract DWF from the Flow Time Series    

Step 9: Assign a UH to at Least 1 Node Using the Inflow Icon  

Step 10: View the DWF Pattern         

Step 11: Create the RDII Time Series          

Step 12: View the RDII Time Series   

Step 13: Run Once Feature to See how Good the Current RTK Parameters are in matching the monitored flow

Step 14: You can use Graph Control to show the mean of the Observed and Predicted RDII on one Graph.        

Step 15: Calibrate the RTK Parameters        

Step 16: Run the GA 

Step 17: Assign the Intermediate Answers  to the UH     

Step 18: View the Calibration Graph  

Step 19: Event Identification   

Step 20: Assign the Found DWF Pattern     

Step 21: Node DWF and RDII Inflow

Step 22: 3 RDII UH's Used in the Simulation of the RDII Flows 

 Figure 1.  RDII Analyst is part of the InfoSWMM or H2OMAP SWMM Suite but the derived RTK parameters can be used in either InfoSWMM, SWMM5, ICM or InfoSewer

InfoSewer Flow Attenuation Sensitivity

InfoSewer Flow Attenuation Sensitivity 

The three Run manager parameters, Maximum Number of Segments, Minimum Travel Distance and the Minimum Travel Distance in InfoSewer and H2OMAP Sewer affect the shape and flow attenuation of the flow in a link.  The effect of using the flow attenuation is to reduce the peak flow and spread out the flow compared to the No Flag option (Figure 1). 

Figure 1.  Effect of the Flow Attenuation Option in infoSewer and H2OMAP Sewer

InfoSWMM 2D Report Variables

InfoSWMM 2D Report Variables

The Junction Graph variables for 2D Depth, 2D Speed, 2D Froude Number, 2D Unit Flow, 2D Inflow, 2D Volume and 2D Angle for a InfoSWMM 2D simulation for up to 1000 years can be plotted in the Report Manager of InfoSWMM.  This is an image of the 2D inflow over a 10 year period (A), all seven graph variables (B) for the mesh triangle associated with the 1D node (C).  The 2D inflow is + for flow out of the node to a mesh triangle and – for flow from the mesh triangle to the  1D junction.

How are Negative Transect Elevations Used in SWMM5?

Subject:   How are Negative Transect Elevations Used in SWMM5?

You can have negative elevations in the Transects of SWMM 5 as the elevations are transformed internally to relative depths above the node inverts in the SWMM 5 engine (Figure 1).   The slope of the link is calculated from the link offset elevations (Figure 3) and the cross sectional information for the irregular link in SWMM 5 (Figure 2) is computed from the Transect data (Figure 4).   The Water Surface elevation of the link is based on the node inverts (Figure 5).

Figure 1.  Transect Editor of SWMM 5

Figure 2.  The Transect Data is Used in the Irregular of HEC-RAS Shape of SWMM 5

Figure 3.  The slope of the link with the Transect is calculated from the link upstream and downstream offset elevations – not the Transectdata which is relative.

Figure 4.  Transect Data Transformed into Tables of Area, Hydraulic Radius and Width from the Transect Data internally in SWMM 5.

Figure 5.  HGL of the Water Surface Elevation from the Node Invert and Link Offset Elevations.

How Does Green Ampt Cumulative Event Infiltration work in SWMM 5?

Subject:   How Does Green Ampt Cumulative Event Infiltration work in SWMM 5?

This graph shows the values of the internal SWMM 5 parameters for Green Ampt Infiltration for the pervious area of a Subcatchment during a simulation.  The parameters are:

·         F or FTOT which is the cumulative event infiltration at the start of a time interval in the internal units of feet in SWMM 5,
·         FU or current moisture content of the upper zone of the of the soil
·         FUMAX which is the saturated moisture content of the upper zone in feet and stays constant during the simulation 

Figure 1.  How FTOT, FU and F change over time

Figure 2.  A closer look at how FTOT or F and FU Change over time in a Green Ampt Pervious Area Simulation.

How is Capillary Suction Head Used in SWMM 5 Green-Ampt?

Subject:   How is Capillary Suction Head Used in SWMM 5 Green-Ampt?

How sensitive is the infiltration loss and rate to the capillary suction head parameter in the SWMM 5 Green-Ampt  infiltration method.   Figure         1 shows how the total infiltration loss and total loss rate vary as you change the suction head from 12 to 6 to 3 inches.    Internally the suction head is used in infil.c of SWMM 5 by adding the suction head to the ponded water on the pervious area in the parameter c1 of the implicit Green-Ampt SWMM5 solution.

C1 =  (Suction Head + Depth of Ponded Water) * IMD or Initial Moisture Deficit

Figure 1.  The sensitivity of the total infiltration loss to the capillary suction head in a continuous simulation

How is the Soil Saturated Conductivity Used in SWMM 5 Green-Ampt?

Subject:   How is the Soil Saturated Conductivity Used in SWMM 5 Green-Ampt?

How sensitive is the infiltration loss and rate to the Soil Saturated Conductivity parameter in the SWMM 5 Green-Ampt  infiltration method.   Figure 2 shows how the total infiltration loss and total loss rate vary as you change the soil saturated conductivity from 1 to 0.1 to 0.01 inches/hour.  Internally, Ks is used to check saturation and in the computation of the soil infiltration rate. Two of the checks are:

·         In low rainfall everything infiltrates as irate less than Infil>Ks and
·         In the check to see if the soil is already saturated. 

 

Figure 1.  The three parameters for Green-Ampt Infiltration in SWMM 5

Figure 2.  The sensitivity of the total infiltration loss to the soil saturated conductivity in a continuous simulation

There are Four factors in Rainfall Dependent Infiltration and Inflow or RDII in SWMM 5

There are Four factors in Rainfall Dependent Infiltration and Inflow or RDII in SWMM 5:

1.   The fractional response to Rainfall or R from 0 to 1
2.   The Time Base of the Unit Hydrograph or T in hours * Dimensionless K Shape Factor
3.   The Sewershed Contributing Area in acres or hectares and
4.   The Maximum, Initial Abstraction and Recovery Rate for R on a Monthly Basis in units of inches, mm or mm/day,
5.   The fifth and probably the most important factor is the Rainfall

How is RDII Storage Simulated in SWMM 5?

Subject:  How is RDII Storage Simulated in SWMM 5?

If you are using the SWMM 5 Rainfall Dependent Infiltration and Inflow(RDII)  feature you can also use the RDII storage parameters to change the RDII runoff by simulating the storage in the Sewershed.   The code in RDII.C as implemented by Lew Rossman of the EPA keeps track of used and unused initial abstraction or IA (Figure 1)

When there is rainfall the following actions are taken:

·         The raindepth available to be convoluted by the RDII unit hydrograph method is reduced by unused IA
·         The amount of IA used up is then updated 

When there is no rainfall

·         A portion of the IA already used is recovered using the recovery rate parameter and the variable IAUsed

Figure 1.  The long term effect of the RDII storage on the generated RDII Unit Hydrographs.  IA1, IA2 and IA3 are the Storage values for the short, medium and long term UH's.