The CUHP program was originally developed in 1971 by Ben Urbonas and Stewart McGuire (URS/KEN R. WHITE COMPANY). The program has been regularly revised for the Urban Drainage and Flood Control District by a number of companies and individuals including, Gary Walkovitz (URS COMPANY), Ben Urbonas and David Lombard (UDFCD), C. R. Wuerz (Merrick and Company), Young S. Yoon and Nien Sheng Hsu (Boyle Engineering Corporation).
The permission of the Urban Drainage Flood Control District to use and reproduce their source code and printed material is gratefully acknowledged.
This page contains the following topics:
The Colorado Urban Hydrograph Procedure Computer Program (CUHPD) has been continually updated since 1971 under the direction of Ben Urbonas of Urban Drainage and Flood Control District.
Some of the major modifications incorporated into the PC version are as follows:
- Variable infiltration with time
- Modifying infiltration by storm event
- Overriding of unit hydrograph shape
- Write output to file for use with flood flow frequency analysis program
- Write storm hydrographs to an output file for subsequent use with Multi#Plan River Routing Routine of HEC#1
- Compile with FORTRAN compiler for IBM PC
- Write storm hydrographs to output file for subsequent use with the routing routine portion of UDSWM2#PC (a modified version of the Runoff Block of EPA's SWMM)
- Modify input format to agree with the 1984 Urban Storm Drainage Criteria Manual (USDCM) revisions
- Dimensional and common statements and some of the logic in the earlier version were modified to be adoptable on an IBM PC#XT
- Plotting routines included in the earlier version are eliminated
- Some input data requirements are simplified to facilitate data preparation effort. It is no longer necessary to define entire hyetographs or to define basin parameters Ct and Cp
- The program has, as an option, a capability of estimating hydrographs for small drainage areas (generally less than 90 acres) for which the original CUHP method is not applicable. The resulting flood peaks in many cases are generally comparable, but not identical to those estimated by the Rational Formula as specified in the Urban Storm Drainage Criteria Manual. To exercise this option, input the time of concentration (Tc) as computed by the rational formula procedure described in the Urban Storm Drainage Criteria Manual
- The program can, as an option, create an input data file containing storm hydrograph values for the purpose of combining and routing these hydrographs through the application of UDSWM2#PC, a version of the runoff block of the Storm Water Management Model (SWMM) originally developed by the U.S. Environmental Protection Agency and modified by the U.S. Army Corps of Engineers
The program requires the input of the design storm either as a detailed hyetograph or, as an option, as a 1#hour depth from which a detailed distribution is computed. The user is referred to the Urban Storm Drainage Criteria Manual for the recommended methodology of developing a design storm. Once the design storm is input or computed, rainfall losses are calculated by the program in accordance with the Drainage Criteria Manual and account for retention and depression storage and for infiltration. See Section 2 in the "Runoff" chapter of the Criteria Manual for the excess precipitation algorithm used by this program.
- The infiltration rate can be handled in two ways for each basin:
- A constant infiltration rate throughout the storm can be specified. To use a constant infiltration rate, the user needs to enter only the initial infiltration rate (INFL).
- A variable infiltration rate based on Horton's equation can be calculated.
Horton's equation is:
= infiltration rate in inches/hour
i = initial infiltration rate in inches/hour
o = final infiltration rate in inches/hour
a = decay coefficient in per second units
t = time in seconds
- Infiltration and depression losses can be varied from storm to storm. To do so, the user inputs multiplying factors with rainfall data for each storm to change the initial and final infiltration decay rate and depression storage values entered with basin data.
FOR EXAMPLE, if the user wishes to use Horton's equation with = 3.0 inches/hour, = 0.5 inches/hour and a 0.0018 per second for the 2-year and 5-year storm and then wants to reduce the infiltration to a constant 0.5 inch/hour rate for the 10-year through 100-year storms, let the Initial Infiltration Rate Correction Factor (CINFL) = 0.17 on the 10-year through 100-year rainfall (storm) data (card B#2) and leave all other correction factors blank. This will multiply = 3.0 in/hr by 0.17 and reduce the initial infiltration rate to 0.51 in/hr, which will then decay rapidly to the final infiltration rate of 0.50 in/hr. If the user has entered rainfall loss adjustment factors with the rainfall data and does not wish to use them for a given basin during a computer run, he can nullify these correction factors by enabling the Ignore Global Correction Factors Flag (XNUL) for the individual basin data (card D). Enabling XNUL will cause the computer to use only the rainfall loss factors entered with basin data.
- Depression storage is entered independently for the pervious and impervious areas. A single correction factor is permitted with each rainstorm input if the user wishes to vary depression storage between storms.
- If the user does not enter any rainfall loss adjustment factors.(leave blanks in the adjustment factor columns) for a given storm, the infiltration and depression storage parameters entered with basin data will be used. Adjustment factors are provided to permit the user to account for the effects of antecedent precipitation on rainfall abstractions.
- Up to 72 rainfall increments may be input for each storm hyetograph. If a detailed storm hyetograph is to be input, the user needs to identify the storm and then input incremental rainfall depths for each time increment of the hyetograph. If the 1-hour depth input option is to be used, the user needs to identify the design storm and then enter the 1-hour depth and the return period (i.e. 2-, 5-, 10-, 50-, or 100-year). The design hyetograph will then be computed by the program using the 2-hour storm distribution recommended in the District's Urban Storm Drainage Criteria Manual. The unit time specified under basin data (use only 5-minute or 10-minute unit time with the 1-hour option) has to be consistent with the time increment used for the tabulation of the design storm. Namely, if a 5-minute unit hydrograph is to be used, then the rainfall data should also be entered using 5-minute time increments.
- A user may input up to 99 rainstorms. Any consecutive block of rainstorms may be called for processing by the basin data. It is possible to input several sets of rainstorms developed for different parts of the metropolitan area and then to specify the specific rainstorms to be used by a given basin. It is also possible to input 5-minute and 10-minute rainstorms and then call the appropriate ones, depending on the unit hydrograph used, for a given basin.
B. Unit and Storm Hydrograph
The computer program will generate a unit hydrograph column matrix for each basin. It will then set up an excess precipitation row matrix for each storm called by the basin card which it then cross#multiplies with the unit hydrograph matrix. The resultant storm hydrographs are then printed out. Unit hydrographs are developed using basin parameters of imperviousness and area and the equations in the Urban Storm Drainage Criteria Manual as revised in 1984. As an option, the values of Cp and Ct, if known or predetermined, can be input directly to override the values computed using the Criteria Manual procedure.
Unlike the earlier version (i.e. CUHPD), CUHPE/PC utilizes the following equation for tp as found in the 1984 revision to the Criteria Manual:
It is no longer necessary to modify the Ct coefficient as was the case with CUHPD.
Because of the speed of the computer, it is not necessary to vary the unit duration of the unit hydrograph in order to save manual calculation time. It is recommended that a 5-minute unit hydrograph be used for all work; however, the user has the option of using any unit time provided the rainfall data used has the same unit time and a hyetograph is defined by the user.
If the 1-hour rainfall input option is used, the user may choose either 5-minute or 10-minute unit duration only; however the 5-minute duration is recommended for all 2-hour storms.
The user needs to input the following basin parameters to generate a unit and storm hydrograph:
Input Parameters. The following basin parameters are needed for the program to generate a unit and storm hydrograph:
Area - Basin area in square miles
Basin Length - The length in miles from the downstream design point of the basin or sub-basin along the main drainageway to the high point on its respective basin or sub-basin. When a basin is subdivided into a series of sub.-basins, the sub-basin length used shall include the distance required for runoff to reach the major channel from the farthest point in the sub-basin.
Centroid Distance - Distance in miles from the design point of the basin or sub#basin along the main drainageway to its respective basin or sub-basin centroid.
Percent Impervious - Portion of the basin surface which is impervious in percent.
Basin Slope - Weighted average slope of the basin in feet per foot. See instructions in the Urban Storm Drainage Criteria Manual to determine the weighted slope.
As an option for small urbanized areas, (e.g. less than 90 acres), you may enter time of concentration in minutes. Procedure for estimating time of concentration is given in the Criteria Manual. By specifying the time of concentration, hydrograph peaks will be computed and displayed using both the CUHP method and the Rational Formula. This option will be exercised only if the 1-hour rainfall depth option is used for storm data (Card B2).
Pervious retention - Maximum depression storage on pervious surfaces in inches.
Impervious retention - Maximum depression storage on impervious surfaces in inches.
Infiltration rate - Initial infiltration rate for pervious surfaces in the basin in inches per hour. If this entry is used by itself, it will be used as a constant infiltration rate throughout the storm. If the next two entries are made, then this value will be used as the initial infiltration rate in Horton's equation.
Decay Exponential - decay coefficient in Horton's equation in "per second" units.
Final infiltration - Final infiltration rate in Horton's equation in inches per hour.
Nullifier of Rainfall Loss Adjustment Factors Entered with Rainfall - To be used if rainfall loss adjustment factors entered with rainfall data are to be nullified (optional).
Optional Input Parameters For Hydrograph Shaping.
The unit hydrograph is developed by the computer using the algorithm used in the 1984 revision of the Urban Storm Drainage Criteria Manual. As noted before, the coefficients C t and C p are computed by the program; however, they can be specified by the user as an option.
The shaping of the unit hydrograph also relies on proportioning the widths at 50% and 75% of the unit hydrograph peak. The proportioning is based on 0.35 of the width at 5010 of peak being ahead of the "time to peak" and 0.45 of the width at 75% of peak being ahead of the "time to peak". These proportioning factors were selected after observing a number of unit hydrographs derived from the rainfall/runoff data collected by the U.S.G.S. for the District.
It is possible for the user to override the unit hydrograph widths and the proportioning of these widths built into the program. For drainage and flood studies within the District, the program values shall be used. If the user has derived unit hydrographs from reliable rainfall#runoff data for a study basin and can develop a "calibrated" unit hydrograph for this basin, this option permits reshaping the unit hydrograph accordingly.
C. Rational Formula Option For Small Catchments
The Colorado Urban Hydrograph Procedure (CUHP) is applicable for basins that are generally larger than 90 acres. When the procedure is applied to smaller basins, it has a tendency to overestimate or underestimate peak runoff rates. The Colorado Urban Drainage and Flood Control District's "Urban Storm Drainage Criteria Manual" suggests the use of the Rational Method for such small basins. In the CUHPE/PC version, an optional routine is incorporated which computes peak runoff rates based on the Rational Method. In addition to basin parameters required for the CUHP, the user may specify the time of concentration for the basin of interest and the CUHPE/PC will then compute and display both peak runoff rates as computed by the CUHP and the Rational Method for comparison purposes. The program also contains a routine that modifies the CUHP procedure for generating hydrographs in such a way that their peaks become compatible with those by the Rational Method for small drainage areas.
1. Calculation of Peak Runoff Rates Based on the Rational Method.
The Rational Method is based on the following formula:
Q is defined as the maximum rate of runoff in cubic feet per second;
C is a runoff coefficient;
I is the average intensity of rainfall in inches per hour for a duration equal to the time of concentration; and
A is the drainage area in acres.
To estimate peak runoff rates using the above rational formula, the following relationships were developed and incorporated in the CUHPE/PC:
The rainfall intensity/duration relationship specified in the Urban Storm Drainage Criteria Manual is as follows:
|DURATION (Minutes)||RATIO TO 1-Hour Rain Depth|
Based on the above relationship, the average intensity for any given duration can be estimated by:
It is the average intensity in inches per hour for a duration of t minutes;
t is the rain duration in minutes; and
I60 is the rain depth in inches for a 1-hour duration.
The Urban Storm Drainage Criteria Manual provides a table specifying values of the runoff coefficient, C, to be used for various land use and storm frequency conditions. In the CUHPE/PC, these values are approximated by
C = Re /Rt
Re is the effective rainfall and;
Rt is the total rainfall for a 2-hour storm as used in the CUHP method.
A value of the runoff coefficient as determined by the above equation is dependent upon rainfall magnitude, imperviousness, depression loss, and the Horton's infiltration equation parameters. On the other hand, the runoff coefficients specified in the Urban Storm Drainage Criteria Manual only vary with imperviousness and storm frequency. However, when typical values of rainfall intensity for a given frequency and depression loss are used, the runoff coefficients generated by the program generally agree with the values of C specified in the Urban Storm Drainage Criteria Manual.
When the user specifies the time of concentration and the 1-hour rain depth, the CUHPE/PC will automatically calculate and display a peak runoff rate based on the above Rational procedure. However, when this procedure is used for a drainage area larger than 160 acres, which is not recommended by District, a warning statement will appear in the output along with the estimated peak.
2. Modification of the CUHP Procedure
As mentioned earlier, the peak runoff rates developed by the CUHP may not be consistent with those by the Rational Method for smaller drainage areas. This inconsistency results from different procedures used to calculate the time to peak used for the CUHP and the time of concentration for the Rational Formula. The differences, however, become small or almost negligible when the following relationship is used to relate the two variables.
tp is the time to peak in minutes,
Tc is the time of concentration in minutes, and
Fi is the impervious area, as a fraction.
In the CUHPE/PC, the above relationship is incorporated to estimate the time to peak for a given value of the time of concentration provided by the user, replacing the CUHP for estimating the time to peak. This optional procedure should be only utilized for small drainage areas (the recommended threshold drainage area is 90 acres). When the procedure is utilized for larger drainage areas greater than 90 acres, a warning statement will appear in the output.
3. Rational Method Options.
The CUHPE/PC program has two options under which it will generate peak flows using the Rational Method.
Under the Rational Formula option (i.e. ICIA = 0 on Card C), if the user does not input a time of concentration (Tc), the program will only generate a hydrograph using the Urban Storm Drainage Criteria Manual (USDCM) procedure; however, if the user inputs a value of TC and the 1-hour rainfall depth, the program will generate a hydrograph using the USDCM procedure and will also calculate the peak flow using the Rational Method as explained earlier.
Under the second option (i.e. ICIA = I on Card C) the user is required to provide an input value for TC and the 1-hour rainfall depth. The program will then generate a storm hydrograph that has been modified using the input TC and will also calculate the peak flow using the Rational Method. This second option is recommended only for areas smaller than 90 acres and should not be used at all for areas larger than 160 acres. Also, this second option has only been tested for areas larger than 10 acres in size and should not be used.
Hydrograph Type (Card C – ICIA)
Rational Formula option for smaller basins:
Rational Formula - (Card C – ICIA = 1)
Use if the basin is less than 90 acres and larger than 5 acres. A storm hydrograph will be estimated using the time of concentration (Card D – TC), specified in this dialog. The peak flow will also be estimated using Rational Formula. Use the one-hour design storm (Card B2) for rainfall.
Hydrograph (CUHP) - (Card C – ICIA = 0)
Use if the basin is larger than 90 acres. The hydrograph will be calculated using the Colorado Urban Hydrograph Procedure described in the UD&FCD Urban Storm Drainage Criteria Manual. If you also use the one-hour design storm (Card B2) and specify the Time of Concentration in this dialog (Card D - TC), peak flows will also be estimated using Rational Formula.
UD-SWMM2-PC Name (IDWB = 0)
The Basin Identification Number that will be used as basin identification by the UDSWM2-PC program. Any three digit number from 001 through 399 is valid. This field is mandatory with the last three Print Options (NSW = 7, NSW = 8, and NSW = 9).
The Basin Description or Comment (max. 60 characters).
If Print Options "Storm Hydrographs and Hydrographs to HEC-1 File", "Storm Hydrographs and Excess Precipitation Info and Hydrographs to HEC-1 File" or, "Standard Print and Hydrographs to HEC-1 File" (NSW = 4, NSW = 5, or NSW = 6).are selected, only the first 34 characters in this field will be used by the HEC-program for its basin comment card.
Save Results to Interface File
If this flag is selected results for this node will be written to an Interface File for later use by XPSWMM.
Save Results for Review
If this flag is selected results for this node will be available for use with the Review Results component of XPSWMM.
Allows you to define the level of detail written to the output file and the optional creation of output files.
Optional Parameters (IOPT)
If this flag is on then optional hydrograph shape factors may be entered.
The basin area in square miles.
The basin length in miles.
Distance To Centroid (CAL)
The distance to the basin centroid in miles. The distance along main flow path from outlet to point opposite (i.e. normal) to the basin centroid.
Impervious % - (PERIMP)
The basin imperviousness In percent.
The weighted basin slope in feet per foot.
Time of Concentration - (TC)
The time of concentration in minutes. This is an optional entry if you selected a CUHP Hydrograph type (i.e. Card C - ICIA=O). If a non-zero value is entered for TC, the program will also display an estimate of the runoff peak using Rational Formula. The storm hydrograph will also be calculated using the CUHP procedure.
A non-zero value is mandatory for if you selected the Rational Formula method (i.e. Card C - ICIA=1). Note, the 1-hour rainfall depth also has to be entered (Card B2). The program will compute and display the hydrograph estimated using TC, and the peak flow using Rational Formula.
Impervious to Pervious Flow - (D)
The fraction of impervious to pervious flow.
Ignore Global Correction Factors - (XNUL)
If this flag is enabled all values of Initial Infiltration Rate, Horton’s Decay Rate, Final Infiltration Rate and Depression Loss Storage (Card B1 and B2 - CINFL, CDECAY, CFNINF and CRET) entered in the Storm Data will be ignored.
Pervious Depression Storage - (POET)
The average maximum depression storage on pervious surfaces in inches.
Impervious Depression Storage - (IDET)
The average maximum depression storage on impervious surfaces in inches.
Initial Infiltration Rate - (INFL)
The initial infiltration rate In inches per hour. If the decay rate and final infiltration rate (i.e. the next 2 fields DECAY and FNINFL) are zero or blank, the initial rate entered here is treated as uniform infiltration rate throughout the storm.
Horton Decay Rate - (DECAY)
Horton's exponential decay rate coefficient in 1/second.
Final Infiltration Rate - (FNINFL)
The final infiltration rate In inches per hour.
Level of DCIA - (NDCIA)
The level of directly connected impervious area.
DCIA - (R)
The fraction of directly connected impervious area.
Unit Duration - (TU)
Unit duration of rainfall increments and of the unit hydrograph If design storm 1-hour depth is used, you are limited to 5-or 10-minute unit duration. Use the 5-minute duration in all cases unless a longer unit is clearly (i.e. very large basin) justified.
The Node Name is used as the Basin Identifier (IDBAS). There is currently a limit of 399 basins in this method.
CUHP Job Control
Description (Card A – COM)
Enter the Job Identification and/or Comment (max. 72 characters).
Rainfall Input Type:
Hyetograph (Card A – ISET = 1) – Select this value if detailed hyetograph(s) will be entered (using Record Set B1).
1-Hr Rainfall Depths (Card A – ISET = 2) – Select this value if only the 1-hour rainfall depth(s) will be entered using (using Record Set B2).
The "All Storms" database contains the names of all the storms that are available in the XP database. The "Storms to Analyze" list is a subset of the "All Storms" list and lists all the storms that will be analyzed when the model is solved. There is no limit to the number of storms that can be created and stored in the XP database but only 99 storms can be analyzed in a single run.
Add – Allows you to create a new storm and add it to the "All Storms" database.
Rename – Renames the currently selected storm.
Duplicate – Duplicates the currently selected storm.
Del – Deletes the currently selected storm.
Edit – Allows you to create or edit data for the currently selected storm.
>> - Allows you to add the currently selected storm to the "Storms to Analyze" list.
<< - Allows you to remove the currently selected storm from the "Storms to Analyze" list.
The respective starting and ending year, month, day, hour, minute, and second of the simulation. This data is only used by the Interface File when you are simulating the hydraulics using XPSWMM.
CUHP Storm Data
Return Period (Card B2 – IRP)
Enter the storm return period (2, 5, 10, 50, or 100).
Description (Card B1 or B2 – NDT11, NDT12, NDT13)
Enter the Storm Identification (date or return period, e.g. “6/11/1938” or “100-Year”) (max. 10 characters).
The name of the Interface File which will store the flows generated by this storm. The Interface File is used by the Statistics, Sanitary and Hydraulics layers of XPSWMM and would typically be used for hydraulic routing of the storm flows through the pipe or channel network.
Initial Infiltration Rate (Card B1 or B2 – CINFL) – Enter the (Optional) Correction Factor for Initial (or Uniform) Infiltration Rate.
Horton’s Decay Rate (Card B1 or B2 – CDECAY) – Enter the (Optional) Correction Factor for Horton's Infiltration Decay Exponent.
Final Infiltration Rate (Card B1 or B2 – CFNINF) – Enter the (Optional) Correction Factor for Final Infiltration Rate.
Depression Loss Storage (Card B1 or B2 – CRET) – Enter the (Optional) Correction Factor for Depression Loss Storage.
1-Hr Rainfall Depth (Card A – ISET = 2, Card B2)
Design Depth (Card B2 – ROH) – Enter the storm return period (2, 5, 10, 50, or 100).
Hyetograph (Card A – ISET = 1, Card B1) - Each hyetograph is limited to 72 unit time increment rainfall depths. If you will use Print Options 7, 8 or 9; namely, write an output file for eventual routing using UDSWM2-PC, then enter only one hyetograph and run each separately. Up to 99 hyetographs may be solved in a single run.
Allows you to enter the incremental rainfall depths.
CUHP Rainfall Data
Rainfall Depths (Card B1 – XR)
Each hyetograph is limited to 72 unit time increment rainfall depths.
Inserts a row above the currently selected cell.
Deletes the currently selected cell.
CUHP Optional Parameters
These are optional basin parameters which can be used to override unit hydrograph parameters Ct and Cp and unit hydrograph widths calculated by the CUHP procedure. Enter data only into those fields for which unit hydrograph variables are to be overridden. Leave all other fields blank.
Coefficient Ct - (Card D1 – CT) overrides the program generated value for Ct.
Coefficient Cp - (Card D1 – CP) overrides the program generated value for Cp.
Unit Hydrograph Width at 50% - (Card D1 – W50) overrides the program generated value for the width of the unit hydrograph at 50% in minutes.
Unit Hydrograph Width at 70% - (Card D1 – W75) overrides the program generated value for the width of the unit hydrograph at 70% in minutes.
Fraction Of W50 Ahead Of Tp - (Card D1 – K50) overrides the program generated value for the fraction Of W50 Ahead of Tp (Default = 0.35).
Fraction Of W75 Ahead Of Tp - (Card D1 – K75) overrides the program generated value for the fraction Of W75 Ahead of Tp (Default = 0.45).
Water Quality Capture Volume - (Card D1 – XWQCV) the water quality capture volume in inches.
Water Quality Drain Time - (Card D1 – XWQCV) the water quality drain time in minutes.
CUHP Print Options
Storm Hydrograph – (Card C – NSW = 0) Print: Basin Parameters, Unit Hydrograph, Hyetograph, Storm Hydrograph, Peak Flow, and Runoff Volume.
Storm Hydrograph and Excess Precipitation Info – (Card C – NSW = 1) Print: Basin Parameters, Unit Hydrograph, Hyetograph, Tabular Calculation of Excess Precipitation, Storm Hydrograph, Peak Flow, and Runoff Volume.
Standard – (Card C – NSW = 2) Print: Basin Parameters, Unit Hydrograph, Peak Flows, and Runoff Volume. (No storm hydrograph).
Standard and Peak Flows to File – (Card C – NSW = 3) Print: Same as Standard Option (NSW=2) above. Write all peak flows to disk file for use with the "Flood Flow Frequency Analysis" program.
Storm Hydrographs and Hydrographs to HEC-1 File – (Card C – NSW = 4) Print: Same as Storm Hydrograph (NSW=0) above. Write all storm hydrographs to disk file for use with HEC-1 flow routing routines.
Storm Hydrographs and Excess Precipitation Info and Hydrographs to HEC-1 File – (Card C – NSW = 5) Print: Same as Storm Hydrograph and Excess Precipitation Info (NSW=1) above. Write all storm hydrographs to disk file as in Storm Hydrographs and Hydrographs to HEC-1 File (NSW=4) above
Standard Print and Hydrographs to HEC-1 File – (Card C – NSW = 6) Print: Same as Standard (NSW=2) above. Write all storm hydrographs to disk file as in Storm Hydrographs and Hydrographs to HEC-1 File (NSW=4) above.
Storm Hydrographs and Hydrographs to UDSWM2-PC File – (Card C – NSW = 7) Print: Same as Storm Hydrograph (NSW=0) above. Write all storm hydrographs to disk file for use with UDSWM2-PC program flow routing routines.
Storm Hydrographs and Excess Precipitation Info and Hydrographs to UDSWM2-PC File – (Card C – NSW = 8) - Print: Same as Storm Hydrograph and Excess Precipitation Info (NSW=1) above. Write all storm hydrographs to disk output file as in (NSW=7) above.
Standard Print and Hydrographs to UDSWM2-PC File – (Card C – NSW = 9) Print: Same as Standard (NSW=2) above. Write all storm hydrographs to disk output file as in Storm Hydrographs and Hydrographs to UDSWM2-PC File (NSW=7) above.
For the last 3 options (NSW = 7, NSW = 8 and NSW = 9) you may process up to 399 basins, but be sure to use only one storm for any one computer run. Assign a new output file name for each run.