Das Projekt "Traceruntersuchungen im mesoskaligen Wassereinzugsgebiet der Dill" wird vom Umweltbundesamt gefördert und von Universität Gießen, Institut für Landschaftsökologie und Ressourcenmanagement, Professur für Landschafts-, Wasser- und Stoffhaushalt durchgeführt. The general knowledge on runoff generating processes, water source areas and flow com-ponents for mesoscale watersheds is limited and mainly based on so called expert knowl-edge. Scientific based investigations focus on small scale catchments and hillslope hydrol-ogy. In the frame of this research project, tributaries of the Dill river and the Dill river itself (catchments area 692 km2) are sampled to obtain further insight to water source areas, flow components as well as information on point and diffuse sources. Water samples are taken (1) along transects for synoptic sampling and (2) in headwaters to determine end members. End member mixing analysis is then conducted to determine source areas whereas synoptic sampling helps to investigate and differentiate point and diffuse sources.