A
full GIS/Watershed Model integration package has been developed by R.K.R.
Hess Associates and Environmental Systems Research Institute (ESRI) to
calculate the input parameters required for hydrologic computer models.
By "clicking" on any point in a watershed, the program will automatically
delineate the subwatershed boundary and drainage area. The program will
then compute drainage patterns, the longest flow path and compute sheet,
shallow concentrated and channel flow regions in order to compute time-of-concentration
and S.C.S. lags. The program will also overlay hydrologic soils groups
and land use to develop impervious and pervious curve numbers, composite
S.C.S. curve numbers and percent impervious areas required of various hydrologic
computer models. The program arranges the data in the required model input
format and will eventually "launch" or run the model. There is also a nonpoint
source pollution component to compute NPS loads for the areas chosen and
can be utilized for NPDES permitting. It should be noted that, although
this model fully automates the watershed modeling process, strict quality
control and checking of data, processing and results should always be performed
on this model as well as any model. Originally developed for the Army Corps
of Engineers HEC-1 hydrologic model, it is also applicable to TR-20, SWMM,
ILLUDAS, PSRM-QUAL, and several other hydrologic models. The model is applicable
for watershed storm water management plans, regional basin siting, "what
if" scenerios for future development, and reservoir design. 
To enter the interactive Storm Water Management Model click HERE.
