丹江口大坝加高后,作为南水北调中线工程水源地,其供水等兴利功能地位更为突出,而汉江上游降雨量的减少及梯级水库的调蓄,大大降低了丹江口水库的可调用水资源量。为充分发挥水库的兴利效益,通过对不同频率的来水进行调节计算,从供水满足率、年均发电量、年均弃水量3个方面计算分析起调水位、来水不确定性和汛限水位对丹江口水库兴利效益的影响。结果表明:①起调水位对来水频率＞90%的枯水年供水效益影响较大,由150 m提高至160 m,水库供水满足率可由44.38%提高至93.42%;对来水频率＜75.7%的年份其影响主要体现在发电上,起调水位越高,年均发电量越高,年均弃水量越小,起调水位由150 m提高至170 m至少可增加发电量10亿kW·h;②来水频率越大,水库供水满足率、年均发电量均越小;水库弃水和供水短缺在来水较丰时同时存在;③丹江口水库夏季汛限水位对水库兴利效益的影响比秋季汛限水位更显著;对至少有2 a为枯水年的3 a调节周期,汛限水位对弃水量的影响最明显;④兴利效益的主要影响因素为起调水位,除水库遭遇连续枯水年外,丹江口水库兴利起调水位为162 m,可满足不同水平年的供水需求。

As the water source of the middle route of South-to-North Water Transfer Project, Danjiangkou Reservoir boasts an ever-increasingly prominent function of water supply and other benefits after the dam was heightened. Nevertheless, the decline in rainfall and the regulation and storage of cascade reservoirs in the upper reaches of Hanjiang River have greatly reduced the transferable water resources of Danjiangkou Reservoir. In order to give full play to the benefit of the reservoir, we calculated and analyzed the influences of the starting and regulating water level, the uncertainty of incoming water and the limited water level of flood season on the benefit of Danjiangkou Reservoir from three aspects: water supply satisfaction rate, average annual electricity generation and average annual waste water level. Results manifested that 1) water level at the incipience of regulation has a great influence on the water supply benefit in dry year when the frequency of incoming water is more than 90%. When water level is raised from 150 m to 160 m, the rate of meeting water supply demand can be increased from 44.38% to 93.42%. When the frequency of incoming water is less than 75.7%, water level mainly affects power generation. The higher the water level at the incipience of regulation is, the higher the annual power generation is, and the smaller the annual waste water is. When water level is raised from 150 m to 170 m, power generation could increase by at least 1 billion kW·h. 2) The higher the frequency of incoming water, the smaller the rate of meeting water supply demand, and the lower the average annual power generation. When incoming water is abundant, water abandon and water supply shortage both exist in the mean time. 3) The influence of flood limit water level in summer on the benefit of Danjiangkou Reservoir is more significant than that of flood limit water level in autumn; in a three-year regulation period with at least two years of low water, flood limited water level exerts a most obvious influence on abandoned water quantity. 4) Water level at the incipience of regulation is the major factor that affects the operation benefit of the reservoir. Except from continuous dry years, the water supply demand of different level years can be met if the water level at the incipience of regulation is 162 m.