Application of HSPF-AGCHEM Module within the WMS for the LeSueur Basin

Simulation Program–Fortran (HSPF) AGCHEM modules into the Watershed Modeling System (WMS). HSPF allows simulation of processes that affect water quality. Often the most significant of these processes are agriculture and chemical processes that take place on agricultural land segments. Such processes include application of pesticides and fertilizers. Included in HSPF are three modules that collectively are referred to as the AGCHEM modules: the PEST (pesticides) module, the NITR (nitrogen) module, and the PHOS (phosphorus) module. The AGCHEM modules allow users to model the processes that take place as part of agricultural practices. Clearly, these modules are indispensable in modeling a watershed for water quality. Thus, the interface to HSPF developed in WMS was modified to contain tools for the access and control of the AGCHEM modules. The purpose of this paper is to provide an overview of the implementation of the interface to the AGCHEM modules in WMS. OBJECTIVES: The objective of this research was to incorporate the AGCHEM module of HSPF into WMS and to demonstrate the utility of the WMS-HSPF AGCHEM modules in developing nutrient balances to better understand nutrient cycling, mass balance, and runof