小浪底水库开发任务的库容要求分析

分析认为，小浪底水库逐步抬高汛期水位沙和调水调沙运用，库区为锥体淤积，由下而上、由低而高逐步淤积，比降变小，主汛期运用水位２５４ｍ，形成高滩槽形态，不影响三门峡坝下水位；支流拦沙库容充分淤积，拉沙库容约８０亿ｍ＾３，若水库一镒抬高水位或主汛期高水位蓄水拦沙，水库为三角和带状淤积，在淤积向坝前推进过程中，洲面淤２高，淤积上延，河床比降增大。为了不影响三门峡坝下水位，主沁期运用水位要降至２４０～２６０

Analysis of Reservoir Storage Capacity Requirement for Xiaolangdi Project Development Task

It is recognized from analysis that there will be no impact on water level at sanmenxia through the operation of the reservoir lifting water level in main flood season step by step to store sediment and adjust water and sediment, and in the way sedimentation in the reservoir will be cone shape and sedimentation happened from lower reaches to the upper, from lower position to the higher, which leads to lower river gradient, high enough sedimentation depth and the river regime of high beach and high channel with operation water level of 254?m in main flood seasons; the storage capacities in tributary reservoirs should be full used by sedimentation; the total sediment storage capacity is 8 billion m 3. If the reservoir lifts water level in one time or store water and sediment under high water level in main flood seasons, the sedimentation shape will be delta and belt, and during develop forward to the dam, the delta surface will be getting higher and higher with sedimentation getting upper reaches, the river gradient become steeper, which should be avoid through best effort in order not to influence the water level in front of Sanmenxia dam and loss of reservoir sediment storage capacity, besides, the operation water level in main flood seasons should be decreased to 240 to 260?m, sediment storage capacity in stem should be decreased by 1.5 to 2.5 billion m 3, high threshold may form at mouths of tributaries and lots of sediment storage capacity may loss because lower sedimentation bases, which must be avoided too. After sediment stored in the reservoir, water level in main flood seasons will go down till 230?m step by step, a balance of high beach and deep channel will reach with average river gradient of 0.033%, which is of no influence on Sanmenxia water level. The selected highest water level for Xiaolangdi is 275?m, restricted water level in main flood season is 254?m, dead water level 230?m, total storage capacity 12.65 billion m 3, effective storage 5.1 billion m 3 for which 4.1 billion m 3 is on beach and 1 billion m 3 is in channel, sediment storage capacity is 8 billion m 3 in initial stage and 7.25 billion m 3 in later stage with average sedimentation reduction of 7.87 billion in the lower Yellow River.