南水北调中线引丹江口水库弃水可调水量分析

南水北调中线工程主要供水目标是华北平原的京、律、冀等地区，汉江丹江口水库是南水北调中线近期工程的水源地，地理位置优越，能自流向京、津地区和黄淮海平原供水，而且水质好。南水北调可调水量受到各方面的关注，近期有专家提出引丹江口水库弃不北调的方案。丹江口水库的弃水可调水量究竟能否满足南水北调（中线）供水区的要求，采用两种方法对比作了深入分析。结果表明，丹江口水库的弃水多年平均可达50亿m^3，但多年平均弃水可调水量仅为12.6～14.5亿m^3，年内分配不均，只发生在汛期的较短时间内，多年平均可调水天数不足25d，年际变化大，有36%的年份完全没有弃水发生。

Analysis on transferable surplus water volume from Danjiangkou reservoir for S-N Water Transfer

The major water service regions of Middle Route S-N WaterTransfer Project are Beijing,Tianjin municipalities and Hebei province in North China plain.Danjiangkou reservoir on Hanjiang river,possessing favorable geographical location,is the water source site in near future for the Middle-Route S-N Water Transfer Project and the water in the reservoir,with high quality,can be transferred to Beijing-Tianjin area and Huang-Huai-Hai plain by gravity flow.S-N transferable water volume aroused the attention from various aspects,and recently some specialists suggested to divert the surplus water of Danjiangkou reservoir to the North.Can the transferable surplus water of Danjiangkou reservoir meet the requirement in water service area of Middle-Route S-N Water Transfer Project.To answer this question,a thorough analysis was carried out by 2 methods.The analysis results demonstrate that the average annual surplus water of Danjiangkou reservoir reaches 5 billion m3,but average annual transferable surplus water is only 1.26～1.45 billion m3,the surplus water occurs unevenly in a year and only in a comparably shorter duration in flood season,the average annual days having transferable surplus water is less than 25 d and there is no surplus water for 36% of the years.