Soil erosion by surface water flow on a stony, semiarid hillslope

Soil erosion on hillslopes occurs by processes of soil splash from raindrop impacts and sediment entrainment by surface water flows. This study invest igates the process of soil erosion by surface water flow on a stony soil in a semiarid environment. A field experimental method was developed whereby erosion by concentrated flow could be measured in predefined flow areas wit hout disturbing the soil surface. The method allowed for measurements in th is study of flow erosion at a much wider range of slopes (2.6 to 30.1 per c ent) and unit discharge rates (0.0007 to 0.007 m(2) s(-1)) than have been p reviously feasible. Flow velocities were correlated to discharge and hydrau lic radius, but not to slope. The lack of correlation between velocity and slope might have been due to the greater rock cover on the steeper slopes w hich caused the surface to be hydraulically rougher and thus counteract the expected effect of slope on flow velocity. The detachment data illustrated limitations in applying a linear hydraulic shear stress model over the ent ire range of the data collected. Flow detachment rates were better correlat ed to a power function of either shear stress (r(2) = 0.51) or stream power (r(2) = 0.59). Published in 1999 by John Wiley & Sons, Ltd.