EnviroScape is a diverse collection of portable, hands-on table top models including non-point source pollution watersheds, hazardous materials, wetlands, landfill, riparian, coastal and groundwater.
HEC-HMS - Hydrologic Modeling System flood hydrology software. Determine peak flow hydrographs for rainfall-runoff events in large river basins or small urban watersheds.
The HSPF Model (Hydrologic Simulation Program Fortran) is a U.S. EPA program for simulation of watershed hydrology and water quality for both conventional and toxic organic pollutants.