Measurement of flood peak effects as a result of soil and land management, with focus on experimental issues and scale

Abstract

As a result of several serious flood events which have occurred since 2000, flooding across Europe is now receiving considerable public and media attention. The impact of land use on hydrology and flood response is significantly under-researched, and the links between land use change and flooding are still unclear. This study considers runoff data available from studies of arable in-field land use management options, applied with the aim of reducing diffuse pollution from arable land, in order to investigate whether these treatments also have potential to reduce downstream flooding. Intensive monitoring of 17 hillslope treatment areas produced a record of flood peak data covering different mitigation treatments for runoff which occurred in the winter of 2007-2008. We investigated event total runoff responses to rainfall, peak runoff, and timing of the runoff peaks from replicates of different treatments, in order to assess whether there is a significant difference in flood peak response between different mitigation options which could be used to mitigate downstream flood risk. A mixed-modelling approach was adopted in order to determine whether differences observed in runoff response were significant. The results of this study suggest that changes in land use management using arable in-field mitigation treatments can affect local-scale runoff generation, with differences observed in the size, duration and timing of flood peaks as a result of different management practices, but the study was unable to allow significant treatment effects to be determined. We suggest that further field studies of the effects of changes in land use and land use management need to upscale towards farm and catchment scale experiments which consider high quality before-and-after data over longer temporal timescales. This type of data collection is essential in order to allow appropriate land use management decisions to be made.

Keywords: Arable agriculture; CC; Contour cultivation; Duration of runoff event (hours); Flood peak; Hillslope experiment; Lag time between peak runoff response and onset of event rainfall; MT; Minimum tillage; Mitigation option; NTL; No tramline; PL; Peak runoff recorded during a rainfall event (l 5 min(−1)); Plough; Q; QDuration; QLag; QPeak; QTotal; Runoff; TL; Total runoff recorded during a rainfall event (l); Tramline (tractor wheel track); Treatment; UD; Up-and-downslope cultivation.