A new splash and sheet erosion equation for rangelands.

Soil loss rates predicted from erosion models for rangelands have the potential to be important quantitative indicators for rangeland health and for assessing conservation practices. Splash and sheet erosion processes on rangelands differ from croplands, where the process is conceptualized in part as interrill erosion. Previous interrill equations were developed from cropland soils where interrill erosion was conceptualized and modeled for small plots, which are not generally large enough to encompass the relative high spatial heterogeneity of rangelands. Also, interrill erosion is usually modeled as a function of rainfall intensity (I) and runoff rate (q) such that I and q are independent of each other. Splash and sheet erosion is the dominant type of erosion on most undisturbed rangeland hillslopes where there is adequate vegetation, and these important erosion processes need to be addressed to develop an appropriate rangeland erosion model. In this study, we developed a new equation for calculating the combined rate of splash and sheet erosion (D ss ) using a large set of rainfall simulation data from the western United States. The equation we propose: D ss = K ss I 1.052 q 0.592 , where K ss is a splash and sheet erosion coefficient, takes into account a key interrelationship between I and q revealed in the data. This equation was successfully evaluated using independent sets of multiple-intensity experimental data. The new equation should enable improved estimation of water erosion on rangelands in the western United States and in other parts of the world.

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