丹江口水库对汉江中下游径流特性的影响

随着汉江流域水资源开发利用程度的提高，汉江径流特性在一定程度上发生了变化，并在一定程度上影响了汉江生态系统的健康。为分析人类活动对汉江径流特性的影响，以白河、皇庄和仙桃3个水文站为研究对象，以丹江口水库关闸蓄水时间划分研究时段，利用3站1955~2006年的日流量资料对比分析了研究时段内汉江中下游年、汛期、非汛期、月及日径流量的变化特性。结果表明：丹江口水库的运行对其下游的年径流特性无明显影响，而对汛期、非汛期、日径流量和径流年内分配有显著的影响，汛期径流量所占比例显著减少，非汛期径流量所占比例显著增加，径流量年内分配过程均匀化，中小量级日流量出现频次增加，大量级日流量出现频次减少，但影响随与水库的距离增加而减小。研究成果可为评价人类活动对汉江生态系统健康及稳定性提供参考.

IMPACT OF THE DANJIANGKOU RESERVOIR ON THE FLOW REGIME IN THE MIDDLE AND LOWER REACHES OF HANJIANG RIVER

With the development and utilization of water resources of Hanjiang River，the flow regime of Hanjiang River has been altered to some extent，and the health of Hanjiang River ecosystem has been influenced to some extent.With the Baihe，Huangzhuang and Xiantao hydrological stations as the study objectives for research of the impact of human activities on the flow regime of Hanjiang River，the study period was divided into two subperiods by the time when the gates of Danjiangkou reservoir were initially closed for water storage.The variations of annual，monthly，daily runoff，and the runoff of wet season and dry season on the middle and lower reaches of Hanjiang River were comparatively analyzed according to the observed data of daily discharges during 1955 to 2006.The result shows that the operation of Danjiangkou reservoir did not affect annual runoff downstream，but led to more even the runoff of wet season and dry season，daily runoff and the monthly runoff distribution downstream，the percentage of wet seasonal runoff decreased significantly，the percentage of dry seasonal runoff increased significantly，the distribution of the runoff was more symmetrical，the frequency of the medium and lower discharge increased，and the frequency of the higher discharge decreased，but the impact was more weaker along with the increase of distance.This paper could provide reference for the assessment of impacts of human activities on the health and stability of Hanjiang River ecosystem.