Soil erosion is recognised as a major source of sediment, nutrients, and soil organic carbon that links the terrestrial eco-system with the atmosphere and ocean on a global and regional scale (Quinton et al. 2010, Kuhn 2010). The University of Basel has developed a unique rainfall erosion laboratory to study the role of raindrop impacts and flow on the mobilization and movements of these materials and chemicals that, upon reaching streams and rivers, may have appreciable impacts on water quality and the biogeochemical cycle. Peter Kinnell is recognised internationally for his work on the forms of and physics involved in rainfall erosion that dominate in these source areas (Kinnell 2011a,b; 2009a,b), whereas Nikolaus Kuhn is known for his work regarding carbon and nutrient transport by rainfall erosion (Kuhn et al. 2011; Kuhn 2010; Kuhn et al. 2009). Bringing together both aspects could create a more holistic understanding of the natural processes involved and make it possible to estimate their importance in respect to climate change, water quality, and the biogeochemical cycle on a local, regional, and global perspective.

Rainfall has a certain power to cause erosion and soils have a certain capacity to resist that power. In the rain-impacted flows that are often involved in eroding surfaces rich in carbon, nutrients and pollutants, the power to cause erosion depends on raindrop size, raindrop velocity, flow depth and flow velocity. In the majority of experiments reported in the literature, the power of the rain-impacted flows and falling raindrops to cause erosion is largely unknown and, as a consequence, the results of the experiments are of very limited value (Torri et al. 1987; Kuhn 2002). Therefore the main aim of this collaboration is the Design and commencement of various pilot experiments to further increase the understand-ing of fundamental soil erosion processes, i.e. the interaction between rainfall and suface flow characteristics in shallow surface flows.