Integrated modelling of hydrological processes and nutrient dynamics at the river basin scale

The paper presents a generic modelling approach for modelling nutrient transfer from soil to surface water in mesoscale river basins. The approach is tested in application of the spatially-distributed coupled hydrological / water quality model SWIM for modelling hydrological processes and nitrogen dynamics in the upper Stepenitz basin (subbasin of the Elbe, 575 km(2)). Both hydrological and hydrochemical validations of the model were successful for this basin. The differences in nitrogen cycling for different soils revealed by the simulation provide a basis for further scenario evaluation and eventually for recommendations for nonpoint source pollution control at the river basin scale.