There are six land uses defined by the model, which are listed in Table 1 below. To define the six land uses described in Table 1, define source areas within the land use with numeric values corresponding to the area of the source area and enter the appropriate parameters for the source area. Each land use grid box lists the 30 source areas (for Freeway land uses, 10 source areas) along with the corresponding area, the control options that are available for the source area, and a message, "Entered," if the data for the source area has been entered.

Table 1. SLAMM Land Uses

1. Residential Land Uses

2. Institutional Land Uses

3. Commercial Land Uses

4. Industrial Land Uses

5. Other Urban Land Uses

6. Freeway Land Uses

Table 2 is a list of the source areas SLAMM uses. The control options available for each source area are illustrated in Table 3.

TABLE 2. SLAMM SOURCE AREAS

Roofs                               Sidewalks/Walks          Other Impervious Areas

Paved Parking/Storage         Streets/Alleys         Freeway Lanes/Shoulders

Unpaved Parking/Storage   Undeveloped Areas                 Large Turf Areas

Playgrounds                Small Landscaped Areas     Large Landscaped Areas

                        Driveways                  Other Pervious Areas

Runoff volumes and particulate loadings from all source areas in each land use are summed and routed to the drainage system, where they are treated by any of the applicable control devices for the drainage system listed in Table 3 below.  The resulting runoff and particulate loadings are then routed to the outfall, where they are treated by any of the applicable control devices for the outfall listed in Table 3 below.

We have prepared five presentations that steps you through the various windows that you will find when using WinSLAMM.  The presentation is set up as PowerPoint presentations placed in a .pdf format.  To view them, download the files and save them on your computer.  The files area:

    WinSLAMM v 9.3.0 User's Guide Introduction.pdf

    WinSLAMM v 9.3.0 User's Guide Output.pdf

    WinSLAMM v 9.3.0 User's Guide Control Devices.pdf

    WinSLAMM v 9.3.0 User's Guide New Features.pdf

    WinSLAMM v 9.3.0 User's Guide Advanced Features.pdf

Each source area listed in Table 2 above has specific data requirements, or parameters, that depend upon the characteristics of the source area and upon the source area's land use. These parameters include the area (acres), the roof slope, the drainage system connection type, the soil type, building density, and alleys.  Not all parameters apply to each source area (see model documentation for details).

Streets and alleys in Land Uses 1 through 5 (See Table 2) require somewhat different characteristic information than Freeways (Land Use 6). To enter a user defined street dirt accumulation equation for a street area in land uses 1 through 5, the equation must be in the form of a quadratic equation, Ax2 + Bx + C, where A is greater than 0, B is greater than 0, and C is less than or equal to 0. A is the minimum street dirt loading possible, based upon street texture. B is the accumulation rate (lbs/day/curb-mile), based upon land use. C is the coefficient expressing the amount of particulates lost to the air as fugative dust, as a function of time.

Isolated areas, or disconnected areas, are areas within a land use that do not contribute runoff to the land use outfall. Isolated areas could be constructed, e.g. swimming pools, or natural land features such as kettle ponds. Source controls are not applicable to isolated areas.

The source areas in the Freeway land use include Paved Land and Shoulder Areas, Large Turf Areas, an Undeveloped Area, an Other Pervious Area, an Other Directly Connected Impervious Area, and an Other Partially Connected Impervious Area. A paved lane and shoulder area requires somewhat different source area parameters than street and alley source. 

TABLE 3. Source Area, Drainage System, and Outfall Control Options

Currently Available in SLAMM (1)

(1) Development characteristics affecting runoff, such as roof and pavement draining to grass instead of being directly connected to the drainage system, are included in the individual source area parameter descriptions.

(2) Use the Biofiltration Control Practice to model infiltration systems.

Output Options

1. SOURCE AREAS BY LAND USE FOR EACH RAIN - COMPLETE PRINTOUT

This output option provides a complete listing of the WinSLAMM output for a model run. Data is listed for each rainfall event in the model run, for all source areas entered for a model run, and for each rainfall event for the outfall. Data is listed for:
1. Runoff volume
2. Particulate concentration
3. Particulate loading
4. Pollutant concentration (for each pollutant)
5. Pollutant loading (for each pollutant)
6. The percent contribution from each source area for runoff, particulate loading, and pollutant loading (for each pollutant).

2. SOURCE AREA TOTALS AND OUTFALL SUMMARIES

This output option provides a listing of the WinSLAMM output for a model run. Data is totaled for for all source areas entered for a model run, and totaled for the outfall. Data is listed for:
1. Runoff volume
2. Particulate concentration
3. Particulate loading
4. Pollutant concentration (for each pollutant)
5. Pollutant loading (for each pollutant)
6. The percent contribution from each source area for runoff, particulate loading, and pollutant loading (for each pollutant).

3. OUTFALL DATA ONLY FOR EACH RAIN

This output option provides a listing of the WinSLAMM output for a model run. Data is listed for each rainfall event for the outfall. Data is listed for:
1. Runoff volume
2. Particulate concentration
3. Particulate loading
4. Pollutant concentration (for each pollutant)
5. Pollutant loading (for each pollutant)
6. The percent contribution from each source area for runoff, particulate loading, and pollutant loading (for each pollutant).

4. OUTFALL SUMMARIES ONLY

This output option provides a listing of the WinSLAMM output for a model run, and is the default option for the program. Data is listed for outfall summaries only. Data is listed for:
1. Runoff volume
2. Particulate concentration
3. Particulate loading
4. Pollutant concentration (for each pollutant)
5. Pollutant loading (for each pollutant)
6. The percent contribution from each source area for runoff, particulate loading, and pollutant loading (for each pollutant).

5. ONE LINE PER EVENT RUNOFF AND FLOW SUMMARY

This output option provides a one-line per event summary of the model run. The output includes the event number, the rain start date, the rain start time, the Julian start date and time, the rain duration, the rain inter-event period, the runoff duration, the rain depth, the runoff volume, the runoff coefficient, the average flow, the peak flow, the suspended solids concentration, and the suspended solids mass. The file is easily imported into Excel for further analysis. The output also includes a statistical summary of each of the output columns. The summary includes:

The number of events (either the total or reduced by the number of zero runoff events)
The total (except for Rsubv, Average Flow, Peak Flow, and Concentration)
Equivalent Annual Total (except for Rsubv, Average Flow, Peak Flow, and Concentration) 
Minimum
Maximum
Average 
Average of All Events 
Median 
Standard Deviation 
Coefficient Of Variation (Standard Deviation/Mean) 

6. CONTINUOUS HYDROGRAPH WITH SIX MINUTE TIME INCREMENTS

This output option will create a comma-separated value ASCII text file that contains continuous hydrograph data and pollutant data from the model run. The hydrograph time increment is six minutes, beginning at the Start Date entered in the Current File Data window and finishing with the End Date entered in the Current File Data window. The flow values are based upon a triangular hydrograph with the peak flow for each event equal to twice the average flow. The duration of each event is assumed to be 1.2 times the rainfall duration. The event mean concentration for particulate solids at the outfall follows the flow, which is followed by the event mean concentration of any pollutants that are selected for the model run. 

This output file, with some manipulation, can be imported into SWMM for use as a drainage system hydrograph and pollutant inlet.

7. CONTINUOUS HYDROGRAPH WITH FIFTEEN MINUTE TIME INCREMENTS

This output option will create a comma-separated value ASCII text file that contains continuous hydrograph data and pollutant data from the model run. The hydrograph time increment is fifteen minutes, beginning at the Start Date entered in the Current File Data window and finishing with the End Date entered in the Current File Data window. The flow values are based upon a triangular hydrograph with the peak flow for each event equal to twice the average flow. The duration of each event is assumed to be 1.2 times the rainfall duration. The event mean concentration for particulate solids at the outfall follows the flow, which is followed by the event mean concentration of any pollutants that are selected for the model run. 

This output file, with some manipulation, can be imported into SWMM for use as a drainage system hydrograph and pollutant inlet.

8. CONTINUOUS HYDROGRAPH WITH SIXTY MINUTE TIME INCREMENTS

This output option will create a comma-separated value ASCII text file that contains continuous hydrograph data and pollutant data from the model run. The hydrograph time increment is sixty minutes, beginning at the Start Date entered in the Current File Data window and finishing with the End Date entered in the Current File Data window. The flow values are based upon a triangular hydrograph with the peak flow for each event equal to twice the average flow. The duration of each event is assumed to be 1.2 times the rainfall duration. The event mean concentration for particulate solids at the outfall follows the flow, which is followed by the event mean concentration of any pollutants that are selected for the model run. 

This output file, with some manipulation, can be imported into SWMM for use as a drainage system hydrograph and pollutant inlet.

WATER BALANCE SUMMARY OF ALL DETENTION PONDS

This output option allows the user to view the event by event water balance for all detention ponds by activating the checkbox accessed through the File/Output Options menu. The output includes the following data:
Pond Source Area Number

Rain Number

Rain Depth (in)

Time (Julian Date)

Maximum Pond Stage (ft)

Minimum Pond Stage (ft)

Event Inflow (ac-ft)

Event Hydraulic Outflow (ac-ft)

Event Infiltration Outflow (ac-ft)

Event Evaporation Outflow (ac-ft)

Event Total Outflow (ac-ft)

Event Flow Balance (ac-ft)

Total  Outflow (ac-ft)

Cumulative Flow Balance (ac-ft)

Other Features

    Batch Processing

The batch processing subroutine for SLAMM allows a user to create either one or a series of sub-basin specific SLAMM .DAT format files. The files are created by entering the area, the soil type, and the land use characteristics of the basin. The batch processor then runs these files as a group. The output from the batch processor run is a comma separated value file that summarizes, for all rain events in the model run, the total runoff, the particulate loading, and the selected pollutant loadings from each sub-basin listed in the batch run.

This process is especially useful for large basin study areas because it allows the user to model many sub-basin areas within the large basin at once.

The program also has the ability to run any selected series of site data file to evaluate the efficiency of selected pollutant control device options and to determine the relative cost of those devices.

    Parameter Modules  

The program contains six editors that create the parameter files needed to run WinSLAMM. A brief discussion of the editors is listed below.

1. Rain Data: Creates files listing rainfall depths, durations, and interevent time periods from actual or stochastically generated rainfall data.  Has the capability to create monthly statistical rainfall data from a multi-year series of rainfall events to assist the user in determining the average annual rainfall year from the multi-year series.

2. Runoff Coefficient Data: Creates files containing the data needed to calculate runoff from specific urban source areas. 

3. Particle Size Data: Creates files describing the particle size distribution of sediment in urban runoff entering detention ponds. 

4. Particulate Solids Concentration Data: Creates files containing the particulate solids concentration data needed by WinSLAMM to predict particulate solids loadings in urban source areas and land uses. 

5. Particulate Residue Reduction Data: Creates files that determine the particulate residue loading remaining in curb and gutter delivery systems after a storm event.  Data in this file will reduce the particulate loading between the total yield without drainage controls and the total yield with drainage controls.

6. Pollutant Probability Distribution Data: Creates files describing pollutant (eg lead, zinc, etc.) concentrations from WinSLAMM source areas and land uses. 

7. Street Delivery Data:  Creates files that describe the fraction of total particulates that are washed from the streets during rains, but are subsequently redeposited due to lack of energy in the flowing water. The delivery subprogram contains the user-defined fractions of the total particulates that do not reach the outfall during a rain event, for different rain depths and street textures. 

These files, along with the help file and the WinSLAMM.exe program, are updated as needed.  Updates for all these files can be found on the Software Updates page.

    Output Viewers  

The program comes with two output viewers (a built-in text view and Notepad) and the capability to export the output to a comma separated value file or ASCII file, depending upon the type of output.