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

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