A conceptual model for simulation of catchment scale nitrate transport

A conceptual catchment-scale model for simulating nitrate transport in rural watersheds is presented. The model consists of a hydrological part and a nitrate transport module. The latter comprises two functions: a production function controlling nitrate release from the unsaturated zone and a transfer function controlling the discharge of nitrate in the surface water. The production function simulates surface runoff and nitrate leaching towards the saturated zone in response to effective rainfall, duration of the leaching period and initial soil nitrate content of the leaching period. The transfer function defines a proportional relation between the catchment soil saturation deficit and the nitrate concentration in the surface water. The model is found to be applicable for two different catchments under humid temperate climatic conditions.