Changes of soil surface roughness under water erosion process

The objective of this study was to determine the changing characteristics of soil surface roughness under different rainfall intensities and examine the interaction between soil surface roughness and different water erosion processes. Four artificial management practices (raking cropland, artificial hoeing, artificial digging, and contour tillage) were used according to the local agriculture customs of the Loess Plateau of China to simulate different types of soil surface roughness, using an additional smooth slope for comparison purposes. A total of 20 rainfall simulation experiments were conducted in five 1m by 2m boxes under two rainfall intensities (0.68 and 1.50mmmin-1) on a 15 degrees slope. During splash erosion, soil surface roughness decreased in all treatments except raking cropland and smooth baseline under rainfall intensity of 0.68mmmin-1, while increasing for all treatments except smooth baseline under rainfall intensity of 1.50mmmin-1. During sheet erosion, soil surface roughness decreased for all treatments except hoeing cropland under rainfall intensity of 0.68mmmin-1. However, soil surface roughness increased for the artificial hoeing and raking cropland under rainfall intensity of 1.50mmmin-1. Soil surface roughness has a control effect on sheet erosion for different treatments under two rainfall intensities. For rill erosion, soil surface roughness increased for raking cropland and artificial hoeing treatments, and soil surface roughness decreased for artificial digging and the contour tillage treatments under two rainfall intensities. Under rainfall intensity of 0.68mmmin-1, the critical soil surface roughness was 0.706cm for the resistance control of runoff and sediment yield. Under rainfall intensity of 1.50mmmin-1, the critical soil surface roughness was 1.633cm for the resistance control of runoff, while the critical soil surface roughness was 0.706cm for the resistance control of sediment yield. These findings have important implications for clarifying the erosive nature of soil surface roughness and harnessing sloped farmland. Copyright (c) 2013 John Wiley & Sons, Ltd.