MODELING OF NONPOINT-SOURCE POLLUTION OF NITROGEN AT THE WATERSHED SCALE

The Watershed Nutrient Transport and Transformation (NTT-Watershed) mo del is a physically based, energy-driven, multiple land use, distribut ed model that is capable of simulating water and nutrient transport in a watershed. The topographic features and subsurface properties of th e watershed are refined into uniform, homogeneous square grids. The ve rtical discretization includes vegetation, overland flow, soil water r edistribution and groundwater zones. The chemical submodel simulates t he nitrogen dynamics in terrestrial and aquatic systems. Three chemica l state variables are considered (NO3-, NH4+, and Org-N). The NTT-Wate rshed model was used to simulate the fate and transport of nitrogen in the Muddy Brook watershed in Connecticut. The model was shown to be c apable of capturing the hydrologic and portions of the nitrogen dynami cs in the watershed. Watershed planners could use this model in develo ping strategies of best management practices that could result in maxi mizing the reductions of nitrogen export from a watershed.