The accuracy of agricultural nonpoint source pollution models depends to a great extent on how well model input spatial parameters describe the relevant characteristics of the watershed. It is assumed that reducing the precision of spatial input parameters affects the simulation results of runoff and sediment yield from the entire watershed. However, there may be no significant increase in the accuracy of models, as a result of more precise topographic or soil information, which increase the input data collection and preparation. The objective of this study was to determine the impact of the mesh size of the digital elevation model, DEM (from 20 to 500 m) and the soil map scale (1/25,000; 1/250,000 and; 1/500,000 scale) within the [...]