Hydrologic Simulation Program – FORTRAN (HSPF) is often the model of choice to characterize the linkage between measured in-stream water quality and hydrology, upstream land use/land management practices, land cover, and pollutant sources (point and non-point). It is the principal model of choice for fecal coliform TMDLs in Virginia.
HSPF is a continuous simulation model and one of the few comprehensive models for linking sources to the receiving water body and determining their fate and transport. This model structure, by definition, considers seasonal variations in precipitation, hydrology, land use, management practices, and point/nonpoint source pollutant contributions.
For adapting the model to the watershed, it is also necessary to utilize HSPEXP in addition to the following software developed by USGS to assist with calibrating HSPF: ANNIE, IOWDM, and WDMUtil. These systems allows the user to interactively edit HSPF input files, run simulations, compare results with observed data, calculate statistics, generate graphics, and provide expert advice on which parameters should be adjusted to improve the results. MapTech software is utilized to facilitate adjustment of model parameters and rebuild User Control Input files. Utilizing this package is MapTech’s preferred approach because it gives important flexibility in configuring the system to gain optimal utilization of the model’s capability to incorporate spatial variability and to utilize shorter (e.g. 15 minute) precipitation and model time intervals when appropriate.