三峡水库汛期泥沙淤积对坝前水位的滞后响应

Delayed response of sedimentation in the flood seasons to the pool level of the Three Gorges Reservoir

河床演变中普遍存在着滞后现象,而以往的三峡水库泥沙研究对滞后现象鲜有考虑。为深入认识三峡水库运行带来的泥沙淤积特征,建立了考虑上游来沙和坝前水位双重影响的泥沙淤积滞后响应模型。基于2003—2017年实测水沙资料,分析了三峡入库水沙特性及汛期泥沙淤积特点,利用滞后响应模型探究了汛期泥沙淤积的滞后规律。结果表明:2003—2012年入库水沙呈现“大水带大沙,少水带少沙”的特点,汛期淤积随坝前水位抬升而增加;2013—2017年入库水沙关系的一致性发生变化,受上游梯级库群拦沙影响,汛期淤积减缓。三峡水库汛期累计淤积与5年线性叠加坝前水位之间有较好的相关关系,汛期淤积不仅与当年来沙和坝前水位运行有关,也与前4年的来沙和坝前水位调度有关。

The delayed response of sedimentation is a phenomenon commonly encountered in the fluvial processes of rivers,while previous studies on the sedimentation of the Three Gorges Reservoir(TGR)give little consideration.A delayed response model of sedimentation is established considering sediment inflow and pool level to investigate the recent sedimentation characteristics at the TGR.Based on the measured data during 2003-2017 and the delayed response model,characteristics of water and sediment inflows,as well as characteristics and delayed laws of sedimentation in the flood seasons are comprehensively analyzed.The results indicate that the TGR exhibits the characteristics of large(low)water inflow and large(low)sediment inflow,and sedimentation in the flood seasons tended to increase in conjunction with the rise in pool levels during 2003-2012.There was a consistent relationship between the water and sediment change,and sedimentation in the flood seasons decreased owing to the operation of cascade reservoirs during 2013-2017.Accumulated sedimentation in the TGR during the flood seasons are closely related to the 5 years′linearly superimposed pool level.This indicates that sedimentation in the flood season is affected not only by the current year′s sediment inflow and pool level but also by the sediment inflows and pool levels of the previous 4 years.