四、三门峡水库修成后下游河床变化及整治问题三门峡水库修成后,将使黄河下游河床,遭受到两方面的变化,其一是纵剖面变化,其二是平面变化。由于三门峡水库拦蓄了大量泥沙,出库水流的含沙量将大为减低,水流为满足本身的挟砂力,将在水库下游引起一般性的冲刷。冲刷自上游逐渐向下游发展,厚度沿程递减,其结果将增大断面,减小比降,使水流挟砂力降低。随着冲刷的向下流发展,上游冲 Fourth, after the completion of the Sanmenxia reservoir into a river bed changes and renovation Sanmenxia reservoir is completed, the lower reaches of the Yellow River will be subject to two changes, one is the vertical section changes, the second is the plane changes. Due to the large amount of sediment trapped in the Sanmenxia Reservoir, the sediment concentration of the outflow will be greatly reduced. The water flow will satisfy the need of sand handling itself and will cause general erosion downstream of the reservoir. Scour gradually from the upper reaches to the lower reaches of the development, the thickness decreases along the way, the result will increase the cross section, reduce the drop, so that the sand flow force with reduced. As the erosion of the downward flow of development, the upstream red