Optimization and Regulation of Operational Mode in Xiaolangdi Reservoir during Later Sediment Retaining Period

摘要

The designed sediment storage capacity in Xiaolangdi Reservoir is7.5 × 109 m3.The reservoir deposition morphology during the whole sediment retaining period is as follows: in initial sediment retaining period,the deposition morphology is a delta.With the continuous deposition in reservoir,the delta vertex moves gradually downstream to dam.And at last,the deposition morphology will be a cone.After that,deposition sufaace will increase and reach designed elevation.During later sediment retaining period,in the process of water and sediment regulation,in most time the reservoir is in water storage condition.The delta deposition morphology can keep relatively large storage capacity.With the same amount of sediment and water storage,compared with cone deposition morphology,the water lever before dam of delta deposition morphology is obviously lower,the backwater length is obviously shorter.The analysis shows that delta deposition morphology is obviously superior to cone deposition morphology in the aspects of optimizing outlet water and sediment process,effectivly utilizing tributary storage capacity,trapping the coarse sand and discharging the fine sand,maintaining effective storage capacity for a long time and so on.The results of mathematical model and physical model preliminarily show that optimizing operational mode of reservoir can keep delta deposition morphology for a relatively long period,slow reservoir deposition velocity,extend sediment retaining life,and increase the amount of sand into the sea.At the same time,it does not obviously decrease sedimentation reducton effect of downstream Gao-cun reach.