中文摘要：

水库溯源冲刷试验是评估在水库速降水位过程中,结合工程控制条件、水沙条件、冲刷时机和初始水库蓄水条件等因素,研究支流拦门沙坎破坏程度对干流溯源冲刷的影响。采用按照水库高含沙模型相似律建立的小浪底水库实体模型开展了4个组次的水库降水库区发生溯源冲刷的试验,第1～4组次库容恢复率依次为11.6%、6.8%、12.2%和6.6%。拦门沙坎破坏越严重,水量越大,库区溯源冲刷量越大,库容恢复率大;侵蚀基准面越低,库区溯源冲刷量大,库容恢复率大;库区淤积量42.00亿m^3时采用降低水位引起库区发生溯源冲刷优于库区淤积量32.00亿m^3。对原有的陕西水利科学研究所与清华大学的逐日溯源冲刷公式在考虑支流促因的基础上进行了改进,说明支流蓄水量进入干流越多,引起支流口以下的干流河段冲刷量越大,其计算结果与实测值满足生产实践精度,可作为多沙河流水库调水调沙方案制定参考。

英文摘要：

Retrogressive erosion is a special phenomenon of fluvial processes,where the channel scour develops from downstream to upstream. Retrogressive erosion occurs due to the rapid reduction in water level,which is closely related to the engineering controlling conditions,water and sediment conditions,scouring time and duration,and initial reservoir conditions. Various impacts of destruction degree of a sandbar in a tributary on the retrogressive erosion in the main stream have been investigated. By use of a physical model for the Xiaolangdi Reservoir,which was constructed based on the similarity laws of sediment-laden physical reservoir model,four tests were conducted to investigate the effect of retrogressive erosion due to lower the pond water level quickly. On the constrain of different sandbars evolved in the tributary of Zhenshui,different flow processes and quantities from the interior tributary caused different sediment processes and quantities of the main stem channel below the branch. Restoration efficiencies of reservoir storage capacity for test 1 to test 4 was 11. 6%,6. 8%,12. 2% and 6. 6%,respectively. More water quantity would be released from the tributary for a severer sandbar destruction degree,which led to a higher restoration efficiency of reservoir storage capacity due to a larger volume of channel scour. In addition,a lower base level of erosion could produce the similar effects. When the volume of reservoir deposition reached 4. 2 × 10^9m3,the scour effect of retrogressive erosion by lowering the pool level would be better than the case with the volume of reservoir deposition of 3. 2 ×10^9m3. The results show that the calculated results are in close agreement with the experimental data. The formula for calculating the daily volume of retrogressive erosion has been improved,which was originally proposed by Tsinghua University and Northwest Institute of Hydraulic Science of China. The resulted from the improved formula indicate that a larger water volume released from the tributary could cause a