Sediment yield reduction associated with land use changes and check dams in a catchment of the Loess Plateau, China

Abstract

Large-scale sediment control efforts on the Loess Plateau of China and resulting reductions in sediment yield have been documented. However, it remains unclear how these control works affect the soil erosion rates and sediment loads at the catchment scale. A combination of field work and modeling exercises was used to examine the effects of land use changes and check dams on the variation of sediment yield at the catchment scale. The Huangfuchuan catchment was selected as a case study. The sediment distributed delivery (SEDD) model was calibrated using both observed sediment load data and sedimentation rates derived from check dams. The study catchment suffered important land use changes with increasing grassland and decreasing bare land, sandy area and arable land from 1990 to 2006. By 2009, 502 check dams with a total storage capacity of 571Mm3 had been built in the study area. Relatively good agreement can be seen between observations and model simulation results. Model applications showed that in a scenario without check dams, the land use changes between 1990 and 2006 caused a remarkable reduction of 31.4% in sediment yield. The check dams without land use changes with respect to the 1990 scenario reduced 51.9% of the sediment yield in the study area. The combination of land uses and check dam construction in 2006 reduced the sediment yield by approximately 80%. Our results indicate that check dams are efficient sediment control measures; however, the accumulation of sediment in check dams may create costly problems in the operation of dams and failures because of their short lives. Therefore, sustainable solutions are needed for sediment management in the check dams, such as sediment pass-through, flushing, or mechanical removal, and a reasonable construction plan is also needed for flood control.