How Does Horton Infiltration Work in SWMM 5?

This sketch summarizes what happens in a SWMM 5 Subcatchment for Horton Infiltration during a storm event:

1.       The event starts out with the potential infiltration rate at the maximum infiltration rate but
2.      Decay starts happening right away and the potential infiltration rate starts decreasing until it reaches the minimum infiltration rate (assuming the storm last long enough),
3.      The actual infiltration rate is the minimum of the rainfall rate or the potential infiltration rate,
4.      Using the Huff distributions for rainfall the runoff does not start happening until the rainfall rate exceeds the potential infiltration rate in these models
5.      The runoff ceases after the rainfall rate becomes less than the current potential infiltration rate later in the storm,
6.      The maximum infiltration volume for Horton caps the storm event infiltration at 10 mm in this example, the infiltration will cease when the cumulative infiltration reaches 10 mm.
7.      Horton Iniltration is a five parameter method

a.      Maximum infiltration rate in mm/hour

b.      Minimum infiltration rate in mm/hour

c.       Decay rate for the change from maximum to minimum infiltration rate

d.      Regeneration rate for the change from minimum to maximum infiltration rate after the storm event ends and

e.      A maximum infiltration volume per storm event in millimeters

InfoSWMM (d/D v. Surcharge d/D)

Subject:   InfoSWMM (d/D v. Surcharge d/D)

What is the difference between the output variables d/D and Surcharge d/D in InfoSWMM and H2OMap SWMM

The d/D is calculated as link capacity based on the midpoint depth of water in the link or Link depth/ Link Maximum Depth

            Since the depth in the link is restricted to the Maximum Depth the d/D value is always between 0 and 1

The Surcharged d/D is calculated from the end node depths at each end of the link

            The two node depths are averaged and the value of Surcharge d/D is the Average Node Depth / Link Maximum Depth,

The value of Surcharge d/D varies from 0 to a large number depending on the maximum depths of the nodes and the possible surcharge depth of the nodes

The value of d/D is based on the middle of the link and the value of Surcharge d/D is based on the average of the node depths at the end of the link.  They may be and often are different.   However, if you have a Surcharge d/D greater than 1 it will indicate at least one end of the link is surcharged.  A Surcharge d/D may be greater than 1 with a d/Dless than 1 due to the ends of the node being surcharged and not surcharged.

·         A Surcharged d/D indicates that at least one end of the link is Full, but
·         A d/D value less than 1 does not preclude that one end may be Surcharged.

Figure 1.  Plot of d/D and Surcharged d/D in InfoSWMM.

How to Use Trace Upstream, Domain Manager and Facility Manager in InfoSewer to Find the CE

Subject:   How  to Use Trace Upstream, Domain Manager and Facility Manager 

in InfoSewer to Find the CE

InfoSewer does not have table of node continuity errors only an overall continuity error balance.  If you have a continuity error then you can use the process of divide and conquer to find the continuity error.  Start at the Outlets and using the Trace Upstream command, Domain Manager and Facility Manager take out whole sections of the network until you isolate the section of the network with the continuity error.    Here are the steps you can take:

Step 1.             Use Trace Upstream Network to find the and place in a Domain the Upstream Network (Figure 1).

Step 2.                          Once the upstream domain is created use the Domain Manager to add in any extra links without nodes (Figure 2)

Step 3.             Make the Domain Inactive using Facility Manger (Figure 3)

Step 4.                        Run the network and check the overall continuity error (Figure 4)

Step 5.                         Continue and repeat until you isolate the area that is the main source of the Continuity Error (CE).

Figure 1.  Trace Upstream Network and Place it in a Domain

Figure 2.  Use Domain Manager to take out links without nodes

Figure 3.  Use Facility Manager to Make the Domain Inactive

Figure 4.  Find and Isolate the Area with the CE.

Water Age in InfoSewer

Note:   Water Age in InfoSewer

InfoSewer and H2OMAP Sewer have a Water Quality option called Time of Concentration (TOC) or Water Age that allows the modeler to estimate the residence time in his or her Sewer Network.    The use of Water Age is simple, you just pick TOC(AGE) as the Water Quality Constituent in the Quality Tab of Run Manager for an EPS simulation and the program will automatically assign a Water Age of 0 hours to all loading Manholes (Figure 1).    The Water Age is another estimate of the travel time in your network in which travel time is the volume of pipes / the average velocity in each pipe.    You can compute the Water Age for each node and in the middle of each link (Figure 2).  

Figure 1.  Map Display of Water Age in InfoSewer

Figure 2.   The Water Age in Each Link is Calculated based on the Current Flow and Volume of the network about the Upstream Node of the Link.

Duluth Minnesota Flooding of June 20, 2012

Subject: Duluth Minnesota Flooding of June 20, 2012

The images come from this Duluth Link.    Radar Map

A series of "training" thunderstorms that all passed over the same region have dumped 4 - 5 inches of rain over a wide swath of Northern Minnesota overnight and early this morning. Nearly 8 inches of rain fell in the Denfeld area of western Duluth. This is more rain than fell in the city's previous worst flood on record, which occurred August 20, 1972. Major flooding is occurring, and only emergency travel is recommended in the city due to flooded roads. system and the saturated ground cannot take much more rain. According to wunderground's weather historian, Christopher C. Burt, the all-time 24 hour precipitation record for Duluth is 5.79" on 8/22 - 8/23 1978; 4.14" was recorded on Tuesday at the airport.

Water overflows from a storm sewer in Duluth, Minn. on June 20.

Duluth Mayor Don Ness said he would declare a state of emergency after the deluge of up to 9 inches of rain that he said caused extensive damage to the port city of about 86,000.

Bob King/The Duluth News-Tribune/AP

This car fell into a huge sinkhole on Skyline Parkway in Duluth.

Bob King  /  Duluth News Tribune

This damage Wednesday was on Duluth's Olney Street.

Major flooding in Duluth, Minnesota
A serious flood emergency is occurring in Duluth, Minnesota. A series of "training" thunderstorms that all passed over the same region have dumped 4 - 5 inches of rain over a wide swath of Northern Minnesota overnight and early this morning. Nearly 8 inches of rain fell in the Denfeld area of western Duluth. This is more rain than fell in the city's previous worst flood on record, which occurred August 20, 1972. Major flooding is occurring, and only emergency travel is recommended in the city due to flooded roads. system and the saturated ground cannot take much more rain.

According to wunderground's weather historian, Christopher C. Burt, the all-time 24 hour precipitation record for Duluth is 5.79" on 8/22 - 8/23 1978; 4.14" was recorded on Tuesday at the airport.


Figure 4. Radar-estimated rainfall from the Duluth, Minnesota radar.

Modeling H2S in InfoSWMM, ICM and InfoSewer

Subject:   Modeling H2S in InfoSWMM, ICM and InfoSewer

You can model Sulfide in InfoSWMM/ICM and InfoSewer using the H2S water quality modeling option which uses BOD5 loading at nodes to estimate the  S concentration in the nodes and links of the network using constant network parameters for: 

1.       The Reaction Rate Coefficient,
2.       The Sulfide Loss Coefficient,
3.       Sulfide Flux Coefficient,
4.       Temperature in Degrees C,
5.       Soluble Sulfide Percentage,
6.       pH for the whole network, and
7.       The Ionization Constant.

Relationship between BOD5 and EBOD

Figue 1.  The concentation  of H2S and BOD5 can be graphed at each node and link.

Figure 2.   Dialogs for H2S and BOD5 in InfoSWMM

Mass Balance for Water Quality in SWMM 5

Subject:   Mass Balance for Water Quality in SWMM 5

The rainfall concentration is listed in the wet deposition row of the Runoff Quality Continuity Table, the washoff such as EMC washoff is listed in the Surface Runoff row.  If you are simulating groundwater quality then it is listed as a separate value in a row of the Quality Routing Continuity table alongside RDII quality, DWF quality and WWF quality. 

Mass and Concentration Water Quality Loadings in SWMM 5

Subject:   Mass and Concentration Water Quality Loadings in SWMM 5

If you have a time series of flow and water quality at a node in SWMM 5 you have the option of using either a Mass loading or a concentration loading (Figure 1).     If you have a concentration then the load to the node internally in SWMM 5 is the flow times the concentration.  Alternatively, if you have Mass loading then the program will calculate the concentration from the flow and the load.  The table below shows some combinations of flow in cfs and load in pounds per day to yield various BOD 5 concentrations it the network nodes and  links (Figure 2).  For example, at a flow of 10 cfs you can get a BOD5 concentration of 100 mg/l with a loading of about 5400 pounds of BOD5 per day (Figure 3).

Figure 1.  If you use a time series load in SWMM 5 you need TWO time series, one for the flow and one for the mass load or concentration.

Figure 2.   The Mass loading needed to generate a concentration at a particular flow rate.

Flow (CFS)	BOD5 (mg/l)	BOD 5 Pounds Per Day
1	1	5.39
1	10	53.89
1	50	269.45
1	100	538.89
1	200	1077.79
10	1	53.89
10	10	538.89
10	50	2694.47
10	100	5388.93
10	200	10777.87
100	1	538.89
100	10	5388.93
100	50	26944.66
100	100	53889.33
100	200	107778.66

Figure 3.  The calculated BOD 5 concentration in the link from the Mass Loading.

Convolution of the RDII UH from R, T and K in SWMM 5

Subject:  Convolution of the RDII UH from R, T and K in SWMM 5

The convolution uses the value of R and the Time Base to estimate the amount of Infiltration and Inflow in the Sewer Network.  The short, medium and long term UH's are estimated at each Wet Hydrology time step to make a smooth hydrograph out of the R, T and  K parameters of the Rainfall Dependent Infiltration and Infiltration Method (Figure 1).  The three UH's can be displaced as well if you use the RTK storage parameters (Figure 2)

Figure 1.  The short, medium and long UH's are convoluted in SWMM 5 from the Rainfall Time Series.

Figure 2.   The Initial Abstraction Depth can be used to shift the generated UH in time or reduce the peak flow and total volumes.

c.

What are the Equations for Weirs in SWMM 5, Part 2?

Subject:   What are the Equations for Weirs in SWMM 5, Part 2?

There are four types of Weirs in SWMM 5:  Transverse, Sideflow, V Notch and Trapezoidal.   The trapezoidal weir is a combination of the Sideflow and V Notch Weir and the Sideflow acts like a Transverse Weir when the flow is reversed (Figure 1).  The Weirs can have zero, one or two end contractions (Figure 2) and the Weir Length is a function of the Weir Setting and Horizontal Weir Length.  A V Notch weir works as Trapezoidal Weir when the Weir RTC Setting is less than 1.0

Figure 1.   Weir Equations in SWMM 5

Figure 2.   Valid Number of End Contractions

Figure 3.  Weir Length Calculations

Water Quality Treatment Removal Variables in SWMM5

Subject:    Water Quality Treatment Removal Variables in SWMM5

The treatment variables for Water Quality in a SWMM 5 storage unit (Figure 1) can be either: 

1.       A Process Variable

a.       HRT or Hydraulic Residence Time

b.      DT or Time Step

c.       FLOW or The Current Inflow

d.      DEPTH or the Mean Flow over the Time Step

e.      AREA or the Mean Area over the Time Step

2.       Pollutant Concentration
3.       Pollutant Removal based on the Removal of Other Pollutants 

With a Wide Range of Treatment Functions (Figure 2).

Figure 1.  SWMM 5 Treatment Variable Names in the Treatment Equation

Figure 2.   Treatment Functions in SWMM 5

How does the Infiltration Maximum Time to Drain the Upper Soil Zone Work in SWMM 5 Green Ampt?

Subject: How does the Infiltration Maximum Time to Drain the Upper Soil Zone Work in SWMM 5 Green Ampt?

You can use the monthly soil recovery factor (Figure 1) in SWMM 5 to change how the Infiltration Maximum Time to Drain the Upper Soil Zone (Figure 2) is computed each month during a continuous simulation. 

The  depth of the upper soil zone in the internal  SWMM 5 units of feet is calculated at the start of the simulation based on the Green Ampt Soil Saturated Hydraulic Conductivity

Upper Soil Zone Depth = 4  * (Soil Saturated Hydraulic Conductivity * 12 * 3600)^0.5 / 12

And the Upper Zone Moisture Depletion Factor  and Infiltration Maximum Time to Drain the Upper Soil Zone is calculated at each hydrology time step in SWMM 5.

Upper Zone Moisture Depletion Factor  = Upper Soil Zone Depth / 300 * 12 /3600 * Monthly Evaporation Recovery Factor

Infiltration Maximum Time to Drain the Upper Soil Zone = 6 / (100 * Upper Zone Moisture Depletion Factor  )

Figure 1.  Monthly Soil Recovery Factor

Figure 2.  Infiltration Maximum Time to Drain the Upper Soil Zone for a Subcatchment

Dry Weather Flow in InfoSWMM and H2OMap SWMM

Dry Weather Flow in InfoSWMM and H2OMap SWMM

Dry weather flow can be added to any node in H2OMAP SWMM.  The dry weather flow is computed as the average flow * the monthly pattern * the daily pattern * hourly pattern * the weekend daily pattern to give the Dry Weather Flow at any time step (Figure 1).   Since the four types of patterns (Figure 2) are all multiplied together then for Saturday and Sunday the hourly pattern and the weekend hourly pattern will both be used.   This will have the effect of overestimating the flow if the multipliers are greater than 1 and underestimating theflow if the multipliers are less than one.  You should enter the  Pattern X for the Weekend Hourly Pattern in H2OMAP SWMM  where

X  = Weekend Hourly Pattern / Hourly Pattern

So that when the pattern X is multiplied by the Hourly Pattern the program will use the intended Weekend Pattern.

Figure 1.  How Dry Weather Flow is Computed in H2OMAP SWMM

Figure 2.  The Four Types of Time Patterns in H2OMAP SWMM, InfoSWMM and SWMM 5 

Example DUPUIT-FORCHHEIMER APPROXIMATION FOR SUBSURFACE FLOW Model in SWMM 5

Subject:   Example  DUPUIT-FORCHHEIMER APPROXIMATION FOR SUBSURFACE FLOW Model in SWMM 5

This example was created from an older SWMM 4 model from 1988 using the SWMM 4 to SWMM 5 converter.  The values for the coefficients in this case are A1 = A3 = 4*K/L^2, A2 = 0, B1 or the exponent or B1=2 or from Appendix X in the SWMM 4 manual from OSU (http://eng.odu.edu/cee/resources/model/mbin/swmm/swmm_6.pdf)

Saving an Output Relate in InfoSWMM directly to Excel using Arc Tool Box

Subject:  Saving an Output Relate in InfoSWMM directly to Excel using Arc Tool Box

The following shows how to make an Excel file directly from a feature table in InfoSWMM

Step 1.  Download the Arc Tool box add on Table to Excel

You can download the python script from here   http://resources.arcgis.com/gallery/file/geoprocessing/details?entryID=95009B25-1422-2418-7FB5-B8638ECB2FA9

Step 2.    Add the Tool to Arc Toolbox and then use the tool to create an Excel CSV File

Step 3.  You can export any of the features in InfoSWMM to CSV

Example FM SWMM 5 model with and without Surcharge Depth

Subject:   Example FM SWMM 5 model with and without Surcharge Depth

You need to use the surcharge depth for a Force Main in SWMM 5 to allow the engine to find the right point on the pump curve and pump up the rising main.  If you do not use a surcharge depth then the flow MAY be very small in the rising main due to a small head difference.  Of course the flow in the force main depends on the pump curve you have entered but having the right downstream head of depth for the link matter as well.  The attached model was created in SWMM 5.0.022