Spatial and temporal variability of event runoff characteristics in a small agricultural catchment

The objective of this study is to investigate the factors that control event runoff characteristics at the small catchment scale. The study area is the Hydrological Open Air Laboratory, Lower Austria. Event runoff coefficient (Rc), recession time constant (Tc) and peak discharge (Qp) are estimated from hourly discharge and precipitation data for 298 events in the period 2013-2015. The results show that the Rc and their variability tend to be largest for the tile drainages (mean Rc = 0.09) and the main outlet (mean Rc = 0.08) showing larger Rc in January/February and smaller Rc in July/August. Tc does not vary much between the systems and tends to be largest at the main outlet (mean Tc = 6.5 h) and smallest for the tile drainages (mean Tc = 4.5 h). Groundwater levels explain the temporal variability of Rc and Tc more than soil moisture or precipitation, suggesting a role of shallow flow paths.