Identification of prevailing storm runoff generation mechanisms in an intensively cultivated catchment

Abstract

Abstract: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.

Experimental determination of the flood wave transformation and the sediment resuspension in a small regulated stream in an agricultural catchment

“…1). The Nučice catchment (49 • 57 49.230 N, 14 • 52 13.242 E) was established in 2011 with the main purpose to monitor and study the rainfall-runoff and soil erosion processes by water originating from intensive rainfall over cultivated fields (Zumr et al, 2015).…”

“…Summer storm-runoff events accompanied by an increase in the concentration of suspended solids in the runoff are characteristic events. The storms cause a short, steep wave with a concentration time of 50 to 240 min (Zumr et al, 2015).…”

“…Based on the monitoring of the natural runoff events, we estimate that the minimum time needed for complete bedload sediment removal with comparable discharge is in the range of 10-24 h (Zumr et al, 2015). Although the amount of sediment transported by the waves decreased within each set of experiments, there was still enough sediment left in the channel that could be released if there were to be a larger wave.…”

“…Minella et al (2008) point out that the transport capacity of the channel may increase, and that the stream bed sediment is easily mobilized during runoff events with no eroded sediment from the catchment. Zumr et al (2015) and also Musolff et al (2015) show that a quick runoff response with no soil erosion on the fields is very commonly observed on cultivated catchments where subsurface runoff or tile drains are the dominant controls. The resuspension regime of the stream bed sediment and the connected nutrient transport depend on the characteristics of the stream, the hydrograph of the flood wave and the actual conditions of the channel (Peterson and Benning, 2013).…”

Hydroclimatic controls on runoff activation in an artificially drained, near‐level vertisolic clay landscape in a Prairie climate

“…Climate change notably has the potential to influence flow activation in agricultural systems by affecting precipitation characteristics such as form, amount, duration, and intensity, as well as soil antecedent moisture and temperature status (Bosch, Evans, Scavia, & Allan, ). Past studies conducted in humid temperate regions have shown that tiles significantly limit the initiation of saturation excess OF (SOF) by removing water from the vadose zone and by suppressing water table rise to the surface (Deasy, Brazier, Heathwaite, & Hodgkinson, ; Zumr, Dostál, & Devátý, ). However, Hortonian (or infiltration excess) OF (HOF) can still be activated when rainfall intensity exceeds the infiltration capacity of soil.…”