黄河小浪底水库运用以来的泥沙淤积特征分析

Analysis of Characteristics of Sediment in Xiaolangdi Reservoir in the Yellow River

基于原型观测资料,分析了小浪底水库入库水沙、水库运用及相应库区泥沙淤积的变化特征。小浪底水库运用以来,平均入库水量为225.23亿m^3,沙量为3.19亿t,入库水沙与历史多年平均值相比显著减少;汛限水位和运用水位则逐步抬高,目前,前汛期和后汛期汛限水位分别为230、248 m。至2015年4月,库区泥沙淤积总量为30.48亿m^3,其中干流淤积量占总淤积量的80.9%;水库平均排沙比约为21.0%,库区淤积物从库尾至坝前沿程细化。库区干流淤积纵剖面基本呈三角洲形态,随着水库的运用,三角洲淤积形态缓慢向坝前推进;上窄下宽的特殊库区地形对调整库区淤积形态有利。库区横断面淤积形态初期为水平淤积抬升,后期宽河段库区则受坝前水位下降期脱离回水的影响,形成有滩、有槽的复式断面形态。库区支流淤积形式主要为干流倒灌淤积,纵剖面淤积形态总体呈锥体变化,横断面呈水平淤积抬升。分析库区泥沙淤积特征有助于小浪底水利枢纽的科学调度运用。

Based on prototype observation data,this paper analyzed the characteristics of incoming water and sediment,reservoir operation and reservoir sediment of Xiaolangdi Reservoir.The results show that the water and sediment are significantly reduced after the Xiaolangdi reservoir operation,and mean annual water quantity and sediment were respectively 22.523×10 8 m 3 and 3.19×10 8 tons.With the deposition of sediment in the reservoir area,flood control limited levels and application level gradually raise,at present,the initial flood level of pre-flood season and latter flood season are respectively 230 and 248 meters.To April 2015,the amount of the reservoir sediment is 3.48×10 8 m 3,and including the main stream and tributaries siltation,the main stream accounts is 80.9%of the total sediment deposition.Since the operation of reservoir,the average desilting ratio is 21%,the sediment in the reservoir area is more and more thinner from the tail area of the reservoir to the front of the dam.The sediment profile of reservoir main stream belonged to delta deposition morphology moved down to the front of the dam,the special reservoir condition of the up-narrow and down-wide is favorable to the adjustment of reservoir sedimentation.In the initial section,the sediment shape of the cross section is raised.In the later period,influenced by the water level in front of dam descending and divorcing from backwater,the sediment shape becomes a composite section with beaches and grooves in the wide reach of reservoir area.The sediment form in the main stream of the reservoir area is water intrusion of tributaries,the overall shape of the sediment in the profile was pyramidal.The sediment of the cross section is horizontal uplift.The analytical results of sedimentation characteristics of the reservoir area benefit for the science dispatch of Xiaolangdi Reservoir.