Influence of check dams on water and sediment processes and deposition patterns under simulated rainfall conditions

The Loess Plateau in China has the highest soil erosion and water loss rates in the world. Therefore, check dams, which are more useful engineering measures, have been established to improve soil and water conservation in small watershed. To determine check dam configuration pattern influence on runoff, sediment yield, erosion and deposition pattern in watershed, we conducted a rainfall simulation experiment using the qiao gully small watershed as our normal-scale model. We analysed the runoff and sediment yield characteristics and deposition patterns under four types of check dam configurations: no dams constructed, dam in first order stream channel, dam in second order stream channel, and dams in both channels. Our findings revealed that the runoff and sediment concentrations increased with time, regardless of check dam configuration. The significant effects of check dams on the evolution of storm runoff processes in a small watershed. Compared to no dams, double dams best inhibited runoff reduction and lowered sediment deposition, while construction of one dam in the primary channel was more effective than one dam in the secondary channel. In summary, check dam construction reduced channel erosion, rill erosion, and bank slope collapse at the channel head, while raising the dam-controlled watershed base level. Our findings provide a reference for designing check dams in optimal configurations on plateaus such as the Loess Plateau. The results of this study are of great practical significance in revealing the process of storm runoff and identifying key parts of soil erosion–deposition in the watershed.