黄土高原典型支流淤地坝拦沙对输沙量减少的贡献

Contribution of sediment retention by check-dams to sediment discharge reduction of typical tributaries on the Loess Plateau

为探明淤地坝拦沙作用对河流输沙量变化的影响,依据淤地坝作用年限、坝控面积、坝控流域侵蚀产沙模数及淤地坝排沙率,确定淤地坝拦沙量的估算方法,并结合2009年淤地坝安全大检查数据,分析黄土高原典型支流淤地坝拦沙对输沙量减少的贡献。延河与皇甫川淤地坝在不同年代的拦沙量分别在92.48万~854.35万t/a与36.47万~1 138.75万t/a之间,淤地坝拦沙量占人类活动影响的比例在一级和二级突变后分别为29.1%、28.5%与8.4%、18.2%;2000年以后延河与皇甫川输沙量减幅均达到85%以上,而淤地坝拦沙量的贡献率分别小于10%和20%。淤地坝的拦沙作用已不是目前输沙量减少的主要因素,但由于土壤侵蚀环境的不同,淤地坝在皇甫川对输沙量减少的贡献比在延河要大。

[Background]This work aims to ascertain the contribution of sediment retention by checkdams to sediment discharge reduction,and to further reveal the attribution of the water and sediment changes in the Yellow River and provide the decision-making basis of check-dam construction on the Loess Plateau.[Methods]The typical tributaries of Yanhe River in the loess hilly-gully region and Huangfuchuan River in the weathered sandstone hilly-gully(pisha)region were selected.On the basis of the safety survey database of check-dams in2009,the operation period of check-dam s,dams-controlled area,erosion-sediment yield modulus of dams-controlled watershed and sediment delivery ratio,the estimation method of the sediment retention were determined,and the contribution of sediment retention by check-dams to sediment discharge reduction in the typical tributaries on the Loess Plateau was analyzed.[Results]The average annual retained sediment amount by check-dams in different decades during1960-2015in the Yanhe watershed ranged from0.92million t/a to8.54million t/a,in which the maximum appeared in the1980s,followed by the1970s(7.89million t/a),the minimum occurred in2000-2009.