The application possibilities of a runoff-simulation model were examined on the landscape scale by scenarios on land use changes. At first, the different and heterogenous input data were modified (aggregation of data, etc.) to enable the calculation processes of the simulation model. For the definition of the scale-dependent application possibilities of the model, the calculations were carried out at different scales. In cooperation with environmental and governmental authorities, test areas with specific land-use conflicts (between forestry, agriculture, nature conservation and water resources management) were selected. Based on the model output, those land-use variants can be highlighted which show positive effects on the quality and quantity of the water resources. The study shows a useful application of a runoff model serving as an instrument for landscape planning and an integral part of landscape-ecological assessments.