... heat balance used for snow-melt and potential evapotranspiration, are taken as spatially constant over the water- shed. Also, the partial linear reservoir coefcients for the groundwater and ... instead of the analytical solution used in the original lumped-parameter water balance model, we are able to easily represent the mass balance of both water and an arbitrary conservative pollutant ... Elmer, A. Hu, H. Manguerra, and A. Parker. 199 8. BASINS V.2.0 user’s manual. Washington, DC: U.S. Environmental Protection Agency Ofce of Water, EPA-823-B -9 8-0 06.Leonard, R. A. , W. G. Knisel, and...