Study on the Variation Characteristics of Runoff and Sediment in Taizihe Watershed, Liaoning Province

Based on runoff and suspended sediment of 9 stream gauging stations and precipitation of 31rainfall statsions from 1973 to 2011 in Taizihe River watershed, areal composition, temporal trend and relationship of runoff and sediment were analyzed. The results showed that the feature of runoff and sediment came from different areas existed above Benxi hydrometric station, while runoff and sediment came from the same area in the Benxi-Liaoyang section, where the erosion and sediment yield were severe, with the percentages of sediment discharge from tributaries larger than the percentages of area and runoff, however, because of reservoirs, a large amount of sediment deposited in this section. The feature of runoff and sediment came from different areas also existed in Liaoyang-Tangmazhai section, with Liaoyang and Lishan as the source of runoff and other areas of sediment. For the 9 hydrometric stations, the average correlation coefficient between precipitation and runoff depth, modulus of sediment yield, and sediment concentration was 0.895, 0.607, and 0.315, respectively, indicating a decreasing correlation. The Mann-Kendall trend test showed there was no trend in precipitation, and insignificant decreasing trends in runoff depth and runoff coefficient. There were 5 hydrometric stations showed significant decreasing trend in modulus of sediment yield and 1 station significant increasing trend. There were 6 hydrometric stations showed significant decreasing trend in sediment concentration and 1 station significant increasing trend. The double mass curves analysis showed that under the same precipitation, the runoff depth of only 3 hydrometric stations decreased from 1997, and under the same runoff depth, decreasing trend in the modulus occurred for 6 hydrometric stations, increasing trend for 1 station, and no trend for 2 stations.