Assessing the hydrological effect of the check dams in the Loess Plateau, China, by model simulations

摘要

Check dams are commonly used for soil conservation. In the Loess Plateau ofChina, check dams have been widely constructed as the principal means toretain floodwater and intercept soil sediments since the 1970s. Forinstance, there are more than 6572 check dams in the Yanhe watershed withan area of 7725 km2 in the Loess Plateau. However, little research hasbeen done to quantify the hydrological effects of the check dams.In this research, the SWAT model (Soil and Water Assessment Tool) wasapplied to simulate the runoff and sediment in the Yanhe watershed. Wetreated the 1950s to 1960s as the reference period since there were very fewcheck dams during the period. The model was firstly calibrated and validatedin the reference period. The calibrated model was then used in the laterperiods to simulate the hydrological effects of the check dams.The results showed that the check dams had a regulation effect on runoff anda retention effect on sediment. From 1984 to 1987, the runoff in rainyseason (from May to October) decreased by 1.54 m3 s?1 (14.7%) to 3.13m3 s?1 (25.9%) due to the check dams; while in dry season (fromNovember to the following April), runoff increased by 1.46 m3 s?1(60.5%) to 1.95 m3 s?1 (101.2%); the sediment in rainy seasondecreased by 2.49 × 106 ton (34.6%) to 4.35 × 106 ton (48.0%).From 2006 to 2008, the runoff in rainy seasondecreased by 0.79 m3 s?1 (15.5%) to 1.75 m3 s?1 (28.9%), and therunoff in dry season increased by 0.51 m3 s?1 (20.1%) to 0.97 m3 s?1(46.4%); the sediment in rainy season decreased by2.03 × 106 ton (79.4%) to 3.12 × 106 ton(85.5%).Construction of the large number of check dams in the Loess Plateau hasenhanced the region's capacity to control the runoff and sediment. In theYanhe watershed, the annual runoff was reduced by less than 14.3% due tothe check dams; and the sediment in rainy season was blocked by up to85.5%. Thus, check dams are effective measures for soil erosion controlin the Loess Plateau.