Fish-scale pits reduce runoff and sediment

Fish-scale pits reduce runoff and sediment

S. Fu, B. Liu, G. Zhang, B. Lu, Z. Ye
ABSTRACT: Soil erosion is a serious environmental problem in mountain areas in Beijing Municipality. Semicircular rainwater retention basins, also known as “fish-scale pits” can effectively reduce runoff and soil erosion and improve land productivity. The aims of this study were to evaluate the effect of fish-scale pits on the reduction in runoff and sediment yield under a heavy rainstorm and to identify parameters for the design of fish-scale pits. Rainfall simulations were carried out on two runoff plots located at Shangxinzhuang Experimental Station, Yanqing, Beijing, with and without fish-scale pits. Results showed that the relative reduction in runoff from the fish-scale plot increased with the rainfall amount before water spillover occurred and then decreased. The relative reduction in sediment from the fish-scale plot first increased with rainfall and then slowly decreased to a constant value. The relative reductions in runoff for 20-year (160 mm), 10-year (120 mm), and 2-year (54 mm) return period daily rainfall were 18%, 28%, and 39%, respectively. The relative reduction in sediment for 20-, 10-, and 2-year return period daily rainfall was approximately 76% in all cases. The rainfall amount had an impact on the relative reduction in runoff, but no significant impact on the relative reduction in sediment after water spillover occurred. The results indicate that fish-scale pits played an important role in reducing sediment under heavy rainstorm conditions. The results will be helpful in the design and maintenance of fish-scale pits.
Keywords. Fish-scale pits, Runoff, Soil and water conservation, Soil erosion.
Published in TRANSACTIONS OF THE ASABE. 2010, 53(1): 157-162