Erosion control of hedgerows under soils affected by disturbed soil accumulation in the slopes of loess plateau, China

Abstract

Soil erosion on disturbed soil accumulations severely threatens the ecological stability of construction sites and their surrounding areas. This study aims to quantify the effects of hedgerows on the hydraulic characteristics of runoff and understand the mechanism of runoff and sediment reduction of hedgerow slopes. A field scouring-erosion experiment was conducted on a typical spoiled ground in “Changwu Agricultural Ecological Experimental Station” of the Loess Plateau in China to explore the effects of hedgerows on erosion control in slopes of disturbed soil accumulation. In experiments, 6 plots, which consisted of three hedgerow plots (H) and three control plots of bare slope (C), with a uniform size of 20 m, 5 m width, and 0.5 m height were constructed with excavated soil. By using three different flow discharges (35, 45, and 55 L/min) on the slope with three different gradients (24°, 28° and 32°), some essential parameters, rate of sediment yield, sediment concentration of runoff, sediment reduction, shear stress, denudation rate, and runoff power, were measured for mechanism analysis. The hedgerows could delay runoff, which meant the initial runoff time of hedgerows obviously lagged behind the control plot about 1–8 min. The capability of runoff generating control by the hedgerows depended on the duration of discharge, which grew first and reduced later. At the later stage, the sediment concentration in the runoff of the hedgerow plots exceeded the control plots, which could be related to transformation of hedgerows between source and sink. The accumulated sediment yields of the hedgerow plots were reduced by 10–45% compared to the control plots. The relationship of the reduction of accumulated sediment yield and duration of discharge could be stated with quadratic function (P < 0.01), which indicated critical runoff time was advanced with increase of slope and flow discharge. Based on the runoff power, the soil erodibility parameter of the hedgerow slopes (3.58 g∙N−1∙m−1) was larger than that of the control slopes (2.83 g∙N−1∙m−1). Hedgerows could hinder soil transport, which not only reduced soil peeling, increased critical shear stress, and critical runoff power but also curbed rill evolution in the lower slope erosion process. The important parameters from this study would be helpful for optimal allocation of hedgerow measures, erosion control and erosion prediction model establishment on disturbed soil accumulation.