水库年平均淤损率影响因素分析

Analysis of factors affecting the annual average deposition rate of reservoirs

水库年平均淤损率是反映水库在某一时段内库容年平均淤损程度的重要指标。分析表明,水库年平均淤损率主要与库沙比(总库容/年平均入库沙量)、水库运用方式、入库水沙过程、水库运行阶段密切相关。通常情况下,水库库沙比越大,淤积占库容的比例就越小,水库年平均淤损率也越小。水库采取有利排沙的运用方式,水库的淤积量就较少,年平均淤损率也较小。有利的入库水沙条件,如大水小沙这样的水沙组合,年平均淤损率也较小。水库运用初期与后期相比,由于库区过水面积较大、流速较低,水流输沙能力较小,泥沙不易排往下游,库区淤积泥沙较多,水库年平均淤损率也较高。因此,降低水库年平均淤损率可以通过增加库沙比、采用有利排沙的水库运用方式和优化入库水沙过程等综合措施来实现。

The annual average deposition rate of reservoirs is an index reflecting the annual average capacity loss of reservoirs within a certain period.The analysis shows that the annual average deposition rate of the reservoirs decreases with the increase of the storage-sediment ratio(total storage capacity/annual average volume of sediment into reservoirs),which is closely related to the operation mode,reservoir sediment inflow process,and sand operation stages of reservoirs.Under normal circumstances,the larger the storage-sediment ratio of reservoir is,the smaller the annual average deposition rate of the reservoirs will be.The reservoirs adopting the operation mode of favorable sediment discharge have less deposition and smaller average annual deposition rates.The reservoir sediment inflow process is also an important factor affecting the annual average deposition rate of reservoirs.Under the conditions of large water flow and small sediment volume,the annual average deposition rate decreases.Generally,in the early stage of reservoir operation,the annual average deposition rate of a reservoir is higher due to the larger water flow area in the reservoir area,smaller sediment carrying capacity of flow,and greater amounts of sediment in the reservoir area.Therefore,reducing the annual average deposition rate of reservoirs can be achieved by increasing the storage-sediment ratio,adopting the reservoir operation mode of advantageous sediment discharge and optimizing the process of water and sediment inflows into reservoir.