Runoff and sediment yield under simulated rainfall on sand-covered slopes in a region subject to wind-water erosion

摘要

Wind-water compound erosion is a complex process that affects 260,000 km(2) in China. Understanding the effects of wind erosion deposition on water erosion is essential to soil and water conservation and ecological construction. In this study, runoff and sediment yield on sand-covered slopes (SS) and bare loess slope (LS) were studied under simulated rainfall experiments. The results showed that runoff in response to 1.0 and 1.5 mm/min rainfall intensities on SS began 31.1 min and 17.5 min later than on LS, respectively, and that runoff start-time increased as the sand-covering thickness increased. The impact of rainfall intensity on the runoff process of SS was greater than that of LS. Sand-covering had a greater effect on increasing sediment yield than runoff amount. Analysis of variance (ANOVA) indicated that the runoff amount and sediment yields of the three sand-covering thicknesses (0.5, 1.0 and 1.5 cm) of SS were all significantly larger than those of LS under 1.5 mm/min rainfall (p < 0.01). However, the runoff and sediment did not increase strictly with increasing sand-covering thickness. The total sediment yields from SS under 1.0 and 1.5 mm/ min rainfall intensities were 23 times and 13 times greater than those from LS, respectively. The relationships between cumulative runoff and sediment yield on LS and SS could be fitted well by linear functions (R-2 > 0.98, p<0.01). The sediment yields showed strong positive correlations with runoff amount on SS (p<0.01). In conclusion, the sand-covered slopes greatly increased soil erosion when compared to the loess slope.