Sediment Characteristics and Sources Tracing of Warping Dam in Sanggan River Basin
[Objective]This study intends to explore the main source of sediment and the evolution of erosion and sediment yield in Sanggan River Basin.[Methods]A typical warping dam in Gaoqiang Township,Yangyuan County was selected as the research object.The composite fingerprint identification technology was used to determine nine fingerprint factors,including soil particle size,SOC,TN,radionuclide(137Cs)and low-frequency magnetic susceptibility,of sediment and its source areas.The evolution patterns of erosion and sediment production in different sedimentation stages of sediment source areas and dam controlled small watersheds were studied.[Results](1)The average content of 137Cs in sediment was relatively low,and it was not significantly different from that of gully wall soil,but it was extremely significantly lower than that of forest-grasslands and croplands soil(p＜0.01),which indicated that the sediment was mainly from gully wall.(2)As the majority of 137Cs content of gully wall was below the detection limit,137Cs was a good indicator for identifying gully wall as the main sediment source but it was difficult to be used for distinguishing multiple sediment sources in the small basin.Through Kruskal-Wallis H nonparametric test and multiple stepwise discriminant analysis screening,the optimal combination of fingerprint factors was TN+Xlfb+SOC,which effectively distinguished the average contribution rate of sediment source areas in small watersheds from 2006 to 2017.The contribution rate followed the order of gully wall(82.68％±8.20％)＞croplands(15.36％±8.46％)＞forest-grasslands(1.96％±0.33％).(3)In the evolution of erosion and sediment yield,gully wall was the main sediment contribution area for a long time,forest-grasslands had weak response to erosive rainfall,and the sediment contribution rate of croplands increased significantly when extreme rainstorm occurred.[Conclusion]Overall,the 137Cs tracing technique was suitable for identifying the main sediment source in the small basin,and the composite fingerprint technique was better at identifying multiple sediment sources.The collapse of gully walls caused by gully erosion was the main cause of severe soil erosion in the Sanggan River Basin.
万方数据
维普
