Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

A clear understanding of a model is important for its appropriate use and avoiding of any misuse. In this study, eleven watershed-scale nonpoint-source pollution models were reviewed: SWAT, HSPF, AGNPS, AnnAGNPS, ANSWERS, ANSWERS-Continuous, PRMS, KINEROS, DWSM, CASC2D, and MIKE SHE. SWAT, HSPF, AnnAGNPS, and ANSWERS-Continuous are long-term continuous simulation models. AGNPS, ANSWERS, KINEROS, and DWSM are single rainfall event models. PRMS, CASC2D, and MIKE SHE have both the long-term and single event simulation capabilities. Mathematical bases of different components of these models were identified and compiled. In this paper, a preliminary summary of the compilation is presented in tabular forms. The flow governing equations and their solution methods used in each of these models are briefly discussed. Suitable temporal and spatial scales of these models are mentioned. The compilation of the mathematical bases of these models would be useful to determine the problems, situations, or conditions for which the models are most suitable, the accuracies and uncertainties expected, their full potential uses and limitations, and directions for their enhancements through combining each others strengths.