Abstract:

Aim at the hydrology conditions under present situation and different schemes of the middle route of China’s southtonorth water transfer project,the effect of the project on water quantity and water quality status in lower reaches of Hanjiang River in low water period is researched from two aspects that are available water resources quantity and water environmental capacity.The assessment method and standard of water security,which are used to evaluate the changes of water security degree before and after transferring water, are put forward.The conclusions are that the effect of water transfer on water quantity security is bigger than that on water quality security after the implement of each scheme;December,January and February in each year are the months when there are more effect of water transfer on water security in low water period;the degree of water security in each month of low water period under present situation is above comparative safety level,and the degree of water security will descend after the implement of water transfer schemes,in which the effect of the scheme Ⅱ is the biggest,but water security degree of the scheme Ⅲ is higher than that of other schemes because of the building of water diversion project from the Yangtze River to Hanjiang River.

Key words: outhtonorth water transfer project, water security, low water period, Hanjiang River