Effects of herbaceous morphology changes on the hydrodynamic characteristics of rocky desertification sloping farmland based on flume experiments

Abstract

The process of herbaceous vegetation decay can impact the hydraulic characteristics of slope runoff, thereby affecting soil erosion. However, there have been limited studies quantifying the influence of this decay process on the runoff hydraulic characteristics within soil patches on rocky desertification slopes. In this study, we conducted indoor erosion experiments using simulated fragmented soil patches of rocky desertification slopes in a flume. The experiments involved three different surface cover morphologies during the herbaceous decay process (overall morphology, root morphology, and bare ground), three slope gradients (5°, 15°, and 25°), and three flow discharges (0.03, 0.10, and 0.16 L·s− 1). Our findings indicate that the hydraulic parameters of slope runoff respond differently to changes in slope gradient and flow discharge. The mean flow velocity is the most responsive to variations in slope vegetation morphology. On bare ground slopes, the mean flow velocity was 12% and 22% higher compared to root and overall slopes, respectively. The Froude number and runoff shear stress are the main factors that alter the hydraulic characteristics of slope runoff under the combined effects of slope gradients, flow discharge, and morphology changes. The Froude number increased by 917%, and the runoff shear stress increased by 836% due to the combined effects of slope, flow discharge, and morphology changes. These research findings provide substantial evidence for enhancing the comprehension of the mechanisms through which the decay of herbaceous vegetation impacts slope hydraulic processes. Moreover, they offer a scientific foundation for enhancing the predictive accuracy of soil erosion process models.