Sand cover enhances rill formation under laboratory rainfall simulation

Authors: REN, ZONGPING - Xian University Of Technology; ZHANG, XING - Xian University Of Technology; Zhang, Xunchang; LI, ZHANBIN - Xian University Of Technology; ZHOU, ZHUANGZHUANG - Xian University Of Technology; LI, PENG - Xian University Of Technology

Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2021
Publication Date: 5/26/2021
Citation: Ren, Z., Zhang, X., Zhang, X.J., Li, Z., Zhou, Z., Li, P. 2021. Sand cover enhances rill formation under laboratory rainfall simulation. Catena. 205. Article 105472. https://doi.org/10.1016/j.catena.2021.105472.
DOI: https://doi.org/10.1016/j.catena.2021.105472

Interpretive Summary: Soil erosion is severe in the Wind-Water Erosion Crisscross Region of China, where Aeolian sand cover may enhance water erosion. In order to evaluate the effects of sand cover on runoff, soil loss and rill information, a series of experiments was conducted in two contrasting treatments. One is a bare loess soil slope serving as a control, and another is a sand-covered loess slope (namely sand cover treatment). Nine simulated rain events, each at an intensity of 90 mm/h for a duration of 60 minutes, were successively applied to each treatment in duplicates. The results showed that the runoff generation mechanism changed from infiltration-excess runoff in the control to subsurface saturation-excess runoff in the sand cover treatment. The runoff initiation was delayed about three folds in the sand cover treatment as compared to the control. Total runoff volumes and total sediment yields in the sand cover treatment in each event were 1.1 to 1.2 times and 1.9 to 9.3 times those in the control treatment. A paired t-test showed that the runoff rates were greater in sand cover than in control in the all events except for the last run at P = 0.05. The soil loss rates were greater in sand cover than in control for all events except the first one at P = 0.05. Measured total rill length, width, and degree of rill dissection in the sand cover treatment were much greater than those in the control. The results clearly indicated that a sand layer over a less pervious loess soil facilitated return flow and thus accelerated rill formation and development. This finding is in line with the common understanding that return flow in soil can cause rill formation and severe erosion. This work should be useful to soil conservationists for controlling rill erosion

Technical Abstract: Soil erosion is severe in the Wind-Water Erosion Crisscross Region of China, where Aeolian sand cover may enhance water erosion. In order to evaluate the effects of sand cover on runoff, soil loss and rill information, a series of experiments was conducted in two contrasting treatments. One is a bare loess soil slope serving as a control, and another is a sand-covered loess slope (namely sand cover treatment). Nine simulated rain events, each at an intensity of 90 mm/h for a duration of 60 minutes, were successively applied to each treatment in duplicates. The results showed that the runoff generation mechanism changed from infiltration-excess runoff in the control to subsurface saturation-excess runoff in the sand cover treatment. The runoff initiation was delayed about three-fold in the sand cover treatment as compared to the control. Total runoff volumes and total sediment yields in the sand cover treatment in each event were 1.1 to 1.2 times and 1.9 to 9.3 times those in the control treatment. A paired t-test showed that the runoff rates were greater in sand cover than in control in all events except for the last run at P = 0.05. The soil loss rates were greater in sand cover than in control for all events except the first one at P = 0.05. Measured total rill length, width, and degree of rill dissection in the sand cover treatment were much greater than those in the control. The results clearly indicated that a sand layer over a less pervious loess soil facilitated return flow and thus accelerated rill formation and development. This finding is in line with the common understanding that return flow in soil can cause rill formation and severe erosion.