Study on Sediment Reduction Effect by Soil Retaining Dam with Different Storage Capacity Allocation Proportion in Dali River Watershed

Analysis and study were carried out by means of mathematical statistics on sediment reduction effect by soil retaining dam with different storage capacity allocation proportion in Dali river watershed of the Yellow River. The results indicate that, sediment reduction by large, middle and small soil retaining dam account for 80.1%, 14.6%, 5.3% of the total reduction; the sediment reduction benefit has reached its maximum since 1990s, amounting to 30.2%, with corresponding storage allocation proportion of 1.84:2.37:5.79.Dam and reservoir have obvious influence on the correlation between rainfall and sediment in the river watershed, sediment transport is reduced by 10 million ton corresponding to annual average flood season rainfall of 350mm in the watershed. Within the sediment reduction capability of soil retaining dam, the sediment reduction volume increase with more rainfall in the flood season, having the feature of the more incoming sediment is, the more sediment reduction will be.