The fact that flash floods initiated in arable catchments are often accompanied by massive sediment and nutrient loads often leads to the assumption that surface runoff is the principle pathway by which runoff reaches watercourses. On the basis of an evaluation of several rainfall-runoff events in a representative agricultural catchment, we show that runoff from cultivated land may be generated in a way similar to that seen on forested slopes, where shallow subsurface runoff is the predominant pathway by which runoff makes its way to watercourses in most runoff events. To identify the predominant runoff pathway, we employed a combination of turbidity measurements and stream discharge data. Suspended sediment flux, a newly introduced index representing the ratio between precipitation duration and total sediment yield, and direction of the discharge-turbidity hysteresis loops were proposed as reflective indicators of the frequency of runoff via different pathways. In our study, most of the events initiated by rainstorms of various intensities and durations resulted in rapid increases in stream discharge. Although we observed temporal variability of topsoil properties attributable to seasonal weather changes and agricultural activities, e.g. bulk density and porosity, runoff generation was mainly driven by precipitation characteristics and the initial catchment saturation.
autoři katalogu : Jana Koudelová, David Stejskal, Jan Tippner, Michal Kloiber, Jiří Bláha, Petr Růžička, Tomáš Kolář, Michal Rybníček, Jaroslav Buzek, Tomáš Dostál, Jaromír Milch, Jan Baar, Dominik Hess, Jan Zlámal, Hanuš Vavrčík, Radek Bryol ; editor: Jana Koudelová ; fotografie: Jaroslav Hrivnák, Michal Kloiber, Jan Kolář, Tomáš Kolář, David Stejskal, Willy Tegel., Seznam zkratek, Obsahuje bibliografii, and Anglické resumé