This project analyses the role of overland flow as a sediment transporting medium affecting surface water quality. The aim is to improve our understanding of the delivery of sediment from agricultural fields on the hillslope to streams, including its role as a vector of nutrients and pollutants. The study focuses on the upper Rhine valley of the Alsace, a sensitive region with known water quality problems. The significance of these superficial fluxes for the water quality problems in this study area of inter-regional concern has not be established yet, in spite of their potency. The research comprises two phases. The first phase is a process study focusing on overland flow, its erosivity and its connectivity to the stream. Based on the findings, a sediment delivery model will be developed in phase 2, which enables the estimation of sediment delivery and sediment-associated pollutants to surface waters. Processes working at the hillslope scale will be generalised to more global concepts to allow modelling at the regional scale. There are strong seasonal patterns in the processes, which affect soil erosion and sediment delivery conditions (i.e. rainfall erosivity, basin hydrology, overland flow generation). The model will account for these seasonal variations and incorporate the calendar of agricultural practises that influence soil conditions, crop cover and nutrient inputs. The model can be applied as an impact assessment tool for climate and land use change.