牛栏江滇池补水工程取水防沙措施的模拟研究

Numerical study of solutions to sedimentation problems of the Niulan River-Dian Lake Water Supplementation Project

德泽水库是牛栏江滇池补水工程的水源工程。由于入库泥沙偏细及水沙运动规律复杂,导致汛期取水口含沙量或浊度偏高,因而对滇池水环境及瀑布公园和盘龙江水景观带来了较大影响。针对在取水口上游干、支流上修建拦沙坝以及新建分层取水口方案,采用三维水沙数学模型研究了其对降低取水口含沙量的效果。模拟结果表明:新建分层取水口能充分利用含沙量的分层特性,较大程度上提高汛期取水含沙量满足要求的时间,使表层取水浊度有47.0%~62.1%的时间达到小于17.1NTU的要求,其余时间取水浊度也较低,只有0%~7.6%的时间大于100NTU。修建拦沙坝能够促进泥沙在拦沙坝以上库区的淤积,降低中层即现有取水口的取水浊度,但降低后的浊度仍然偏高,达标时间占比仅为13.9%~18.5%,与建坝前接近。总体来看,新建分层取水口方案在提高取水含沙量满足要求的时间上较修建拦沙坝方案有明显优势,可作为牛栏江滇池补水工程取水防沙措施的首选方案。

The Deze Reservoir is the water source for the Niulan River-Dian Lake Water Supplementation Project.The very fine incoming sediment and the complicated flow and sediment transport processes in the reservoir have led to high sediment concentrations and turbid water in the intake during floods,which has an adverse impact on the water environment of Dian Lake,Kunming Waterfall Park and Panlong River.This study investigated the effects of two solutions for reducing the intake sediment concentration by three-dimensional modeling.One solution is the construction of check dams in the mainstream and its tributaries while the other is the construction of a new multi-level water intake.The simulations show that the new multi-level water intake designed based on the stratification characteristics of the sediment concentration will increase the length of time until the sediment concentration exceeds the desired limits.The modified intake design keeps the surface layer turbidities to lower than 17.1 NTU during the flood season for between 47.0% and 62.1% of the time surface layer turbidities larger than 100 NTU for less than 7.6% of the time.The check dams will accelerate the deposition upstream of the check dams and reduce the water turbidity at the existing water intake;however,the turbidity is still high with the surface turbidity below the limit for only 13.9%-18.5% of the flood season,which are not much better than the values without the check dams.Thus,the multi-level water intake is the better choice for solving the sediment problems of the Niulan River-Dian Lake Water Supplementation Project because it provides longer periods of low turbidity than the check dams.