Impact of cornstalk buffer strip on hillslope soil erosion and its hydrodynamic understanding

Soil erosion is still a serious concern on the Loess Plateau of China. Cornstalk buffer strips are not commonly utilized for erosion control on the Loess Plateau, and there is little hydrodynamic understanding of this soil erosion control practice. A simulated rainfall experiment was designed to investigate how a cornstalk buffer strip affected soil erosion and to enhance the hydrodynamic understanding of this method. Large loessial soil beds (10 m-long, and 3 m-wide) with slope gradient of 20° were subjected to three successive simulated rainfall events with intensities of 100 mm h− 1 for each experimental run. The rainfall events were conducted by a down sprinkler rainfall simulator system. Two treatments (with and without a cornstalk buffer strip) were tested in the following four runs: 1) without cornstalk buffer strip, 2) with cornstalk buffer strip in the third rain event, 3) with cornstalk buffer strip in the second rain event, 4) with continuous cornstalk buffer strip in all three successive rainfall events. In treatments with buffer, a 1 m-width cornstalk buffer strip was applied. The results showed that, compared with the run without cornstalk buffer strip, the run with continuous cornstalk buffer strip in three successive rainfall events reduced sediment yield by 29.1% while the other two runs with cornstalk buffer strip in a single event only reduced sediment yield by 2.0%-9.1%, and early buffer run had a larger reduction in soil erosion than late buffer run. The runoff-sediment relationship coefficients revealed that cornstalk buffer decreased the sediment concentration and increased the runoff threshold required for soil erosion initiation. Moreover, the buffer strip increased sheet flow velocity in interrill areas, while it decreased concentrated flow velocity in rills. This promoted a shift of rill flow to subcritical laminar flow which reduced sediment yield. Cornstalk buffer strip also increased the critical hydrodynamic forces required for the initiation of soil erosion.