皇甫川流域含沙量-流量关系年内年际变化特性

Intra-and Inter-annual Variations in the Relationship Between Suspended Sediment Concentration and Discharge of the Huangfuchuan Watershed

研究不同时间尺度的水沙关系对认识流域土壤侵蚀和泥沙输移有重要意义.本文基于皇甫川流域1958~2015年的含沙量及流量数据,采用方差分析,分析了3时间尺度(次洪过程、日、月)不同流量级含沙量及含沙量-流量关系的年内年际变化特性.结果表明:次洪过程、日和月尺度含沙量与流量之间均显著符合幂函数关系(p<0.05);年内发生多场洪水过后,由于泥沙补给限制,次洪过程含沙量-流量幂函数关系中的系数a显著降低,指数b增加;随水土流失治理及退耕还林(草)措施的开展,与1958~1984年对比,1999~2015年次洪过程各流量级对应的含沙量显著降低,3时间尺度含沙量-流量幂函数关系均发生显著变化,但各时间尺度系数a和指数b的变化模式存在差异,表明不同时间尺度下水沙关系对人类活动的响应模式不尽相同.

Investigating flow-sediment relationships across multiple timescales is meaningful to understand the erosion and transport of materials within watersheds.Based on flow discharge(Q)and suspended sediment concentration(SSC)data at Huangfu station located in the Huangfuchuan Watershed from 1958 to 2015,we analyzed the intra-and inter-annual variations in SSC-Q relationship at different time scales(flood events,daily and monthly)by using the method of analysis of variance.The results show that the SSC-Q relationships in those three timescales can be described by the power-law sediment rating curve(SRC).After several flood events during a year,the coefficient a of SRC decreases and the corresponding exponent b increases significantly due to the limited sediment supply.Compared with 1958~1984,the SSC under different flow conditions within the timescale of flood events decreases significantly with the implementation of soil and water conservation measures in 1970~1980 and Grain for Green project since 1999.The SRCs in flood events,daily and monthly timescales in 1999~2015 show significant changes and the SRC fitting parameters vary in different ways at different timescales.The SRCs reveal time-dependent vitiations over different periods and time scales in response to land use/cover changes caused by human activities.