小北干流有坝放淤引水时机及规模分析研究

利用龙门断面近20年的实测水文、泥沙及龙门-潼关河段的冲淤量资料，分析研究小北干流有坝放淤的引水引沙条件、引水时机及引水规模。研究成果表明：当龙门断面流量大于400m^3／s、含沙量大于40kg／m^3、泥沙中值粒径大于0．025mm时，开始引水，淤区引粗泥沙较多。根据设计的来水来沙条件，满足上述引水引沙条件，并考虑引水闸规模投资等，确定引水规模为800m^3／s，则年平均引沙量为1．22亿t，粗、中、细沙的引沙量分别为0．27亿、0．35亿、0．60亿t。

Study on Occasion and Scope of Diversion for Warping with Cofferdams in Xiaobeiganliu

The paper analyzes and studies the conditions of diversion,occasion of diversion and diversion scope for warping with cofferdams conducted in Xiaobeiganliu by utilizing the about 20-year observed hydrological and sediment data of Longmen Cross Section and data of scouring and deposition of Longmen-Tongguan Section.The outcomes show that when the discharge is greater than 400 m3/s,sediment concentration greater than 40 kg/m3 and the median particle diameter of sediment greater that 0.025 mm of Longmen Cross Section,it starts diversion and the majority of sediment is coarse sand in warping area.The decided diversion scope is 800 m3/s and the mean annual diverted sediment 122 million tons,of which,coarse,medium and fine sands are 27 million tons,35 million tons and 60 million tons respectively according to the conditions of coming water and sediment and the above diversion conditions should be met and considering the investment for intake gates.