降雨量和水土保持对皇甫川输沙量变化的贡献率分析

Contributions of Rainfall and Soil and Water Conservation to the Variation in Sediment Discharge of the Huangfuchuan River Basin

为探究黄河支流输沙量减少与流域内降雨量变化及水土保持措施的定量关系。以黄河中游皇甫川流域为研究区域,基于1960—2015年准格尔气象站日降水量、皇甫水文站年径流量和年输沙量数据,分析对皇甫川流域年径流量与年输沙量有影响的降雨量参数。通过双累积曲线法和突变点检验法确定输沙量变化的3个典型时期:Per1(1960—1986年)、Per2(1987—1999年)和Per3(2000—2015年);计算了降雨量变化、植被恢复和工程措施对该流域不同时期输沙量变化的贡献率。结果表明:(1)1960—2015年皇甫川流域降雨强度超过25 mm/d的降雨减少,径流量和输沙量呈显著减少趋势(M—K检验Z<0,p<0.01);(2)因水土保持引起流域下垫面条件的改变,当Per3与Per1时期中有相似降雨量的年份,Per3时期这些年份的输沙量比Per1时期显著减少,减小范围为50.2%~98.6%;(3)1987—1999年植被恢复和工程措施的减沙贡献率分别为73.0%和38.4%,2000—2015年降雨量变化、植被恢复和工程措施的减沙贡献率分别为11.5%,69.8%和18.7%。研究结果定量计算了降雨量变化和水土保持对皇甫川流域输沙量减少的贡献率,有助于阐明黄河中游沙量锐减的原因。

The Huangfuchuan River Basin was taken as the study area to explore the quantitative relationship between the sediment discharge reduction and rainfall variation,as well as soil and water conservation measures in tributaries of the middle Yellow River.Based on the data of daily precipitation at the Jungar meteorological station and annual runoff and sediment discharge at the Huangfu hydrological station from 1960 to 2015,the precipitation parameters affecting the annual runoff and sediment discharge in the Huangfuchuan River Basin were analyzed.Three typical periods of sediment discharge variation were Per1(1960-1986),Per2(1987-1999),Per3(2000-2015)using the double mass curve analysis and the Pettitt test,and the contribution rate of rainfall change,vegetation restoration and soil and water conservation measures to the variation in sediment discharge in different periods is calculated.The results showed that:(1)During the period of 1960-2015,the daily rainfall intensity exceeded 25mm/d reduced in Huangfuchuan River Basin,and the runoff and sediment discharge also displayed a decreasing trend(with the parameter Z<0 and P<0.01 using the M—K trend tests);(2)Due to the change in the underlying surface caused by water and soil conservation measures,when the years with similar rainfall in Per3 and Per1 periods,the sediment discharge in these years in Per3 period was significantly reduced compared with that in Per1 period,with a reduction range of 50.2%~98.6%;(3)During the period of 1987-1999,the contribution rates of vegetation restoration and soil and water conservation measures to the reduction of sediment discharge were 73.0%and 38.4%,respectively.during the period of 2000-2015,the contribution rates of rainfall change,vegetation restoration and soil and water conservation measures were 11.5%,69.8%and 18.7%,respectively.The results of this study quantitatively calculate the contribution rate of rainfall variation and soil and water conservation measures to the reduction of sediment discharge in the Huangfuchuan River Basin,which is helpful to identify the causes for the sharp reduction of sediment discharge in the middle Yellow River.