INTEGRATED ASSESSMENT AND ANALYSIS OF PHYSICAL LANDSCAPE PROCESSES THAT IMPACT THE QUALITY AND MANAGEMENT OF AGRICULTURAL WATERSHEDS
Location: Watershed Physical Processes Research Unit
Title: The application of RUSLE2 to evaluate the impacts of alternative climate change scenarios on runoff and sediment yield
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 19, 2012
Publication Date: N/A
Interpretive Summary: The Revised Universal Soil Loss Equation, Version 2 (RUSLE2) is a conservation planning tool that predicts soil erosion by water as influenced by climate, soil, topography, and management practices. Extensive databases describing these factors have been developed and are widely used in the USA. This paper describes and illustrates recent developments that extend this tool for use within a Geographical Information System and allow calculation of both hillslope and concentrated flow (ephemeral gully) erosion. A climate change analysis was conducted by applying the model to a representative hillslope profile farmed with conventional-tillage corn. Increasing monthly temperature, rainfall depth and rainfall intensity each by 10% increased sheet and rill erosion by 47%, increased runoff by 33%, and increased ephemeral gully erosion by 53%. These results demonstrate that modest and expected changes in climate will significantly increase the risk of soil erosion and improved conservation management will be an important part of successful adaptation.
The Revised Universal Soil Loss Equation, Version 2 (RUSLE2) provides robust estimates of average annual sheet and rill erosion for one-dimensional hillslope representations. Extensive databases describing climate, soils, and management options have been developed and are widely used in the USA for conservation planning. The increasing availability of high resolution topographic information creates opportunities for Geographical Information System tools to automatically delineate the location of concentrated flow areas where RUSLE2 hillslope profiles end. Recent RUSLE2 enhancements to allow estimation of erosion and runoff from a representative sequence of runoff events that are suitable for linkage with an ephemeral gully model. This paper reviews the sensitivity of RUSLE2 erosion estimates to possible climate change scenarios, demonstrates its ability to evaluate alternative management adaptations, and compares predictions with observations of runoff and sediment yield from the a 6.6 ha (16 acre) research watershed located near Treynor, IA. When applied to a representative hillslope profile farmed with conventional-tillage corn, increasing monthly temperature by 0.8 oC (1.5 oF) and rainfall depth, rainfall erosivity density, and 10-yr, 24-h rainfall depth each by 10% cumulatively increased sheet and rill erosion by 47%, increased runoff by 33%, and increased ephemeral gully erosion by 53%, assuming there was no change in corn yield. If the climate changes decreased corn yield by 10%, the overall effect was to increase soil loss for conservation planning by 63%. These results demonstrate that modest and expected changes in climate will significantly increase the risk of soil erosion and improved conservation management will be an important part of successful adaptation.