Effect of surface rock fragment cover on soil erosion and sediment using simulated runoff

Rock fragments cover is a key factor for soil erosion control, particularly in arid and semiarid environments where vegetation cover is low. The objective of the present research was to study the influence of rock fragment cover on soil erosion and the hydraulic properties of surface flow. The investigation was conducted using a flume with 6 m length, 0.5 m width, and 3% gradient. The treatments included rock fragment cover (0%, 10%, 20%, and 30%), and three levels of flow discharges (3, 6, and 9 lit. min-1). Velocity of water flow decreased 69.2%, the Manning roughness coefficient increased from 0.012 to 0.115, and the Froude number decreased from 2.24 to 0.28 with an increase in rock fragment cover. The Reinhold’s number showed a small variation among different rock fragment covers, but increased with increasing flow discharge. In addition, the rate of soil loss averagely decreased 80.1% in different flow rates with a rise in rock fragment cover from 0 to 30%. Decreasing soil loss rate was related to rock fragment cover by an exponential function.