淤積過程水流引入水库的全部推移質泥沙及大部悬移質泥沙,由於库中流速緩慢沉落和堆積在库底上,泥沙淤积時依它的粒径分类:最大的砂粒(礫石及石子)堆积在上游库底上,较小的被冲淤在下游库底上,而最细的浮游颗粒(淤泥質的細沙)則被水流挟淤在全庫槽上。在上游库底淤成沙坵之后(見图一),当库中水位升降时把泥沙逐渐地向下游冲移而更均匀地遍布全庫槽:在死庫容水位以下则停止冲移泥沙作用,所 Siltation process All the pumped silt and most of the suspended sediment introduced into the reservoir flow into the reservoir. Due to the slow sedimentation and accumulation of sediment on the bottom of the silo, the sediment is classified according to its particle size: the largest sand (gravel And pebbles) are deposited on the bottom of the upper reservoir, and the smaller ones are scoured and silted on the bottom of the downstream reservoir. The finest suspended particles (muddy sand) are silted in the reservoir by silt streams. After silting in the upper reaches of the reservoir (see Figure 1), when the water level in the reservoir rises and falls, the sediment is gradually washed downwards to be more evenly distributed throughout the whole reservoir: sediment is suspended below the level of the dead storage water Role