The Influence of the West Route South-North Water Transfer Project for Runoff of Upper Reaches of the Yangtze River

The watershed river channels flow concentration model and the reservoir operating model are built to simulate and analyze the runoff processes in upper reaches of the Yangtze River,considering 80 reservoirs which play major roles in upper reaches of the Yangtze River.The results showed that(1)The water transfer project reduced the runoff volume of the affected river systems significantly,among which the Yalong river was reduced most;(2)The runoff in non-flooding months decreases significantly also because of the reservoir regulation,and the discharge change amplitude decreased as the distance from the diversion point extends;(3)After the water transfer,the operation conditions of the principal reservoirs in the watershed could affect the watershed runoff evidently,and its ability of adjusting watershed runoff would be impaired in large amount once it could not be fully stored at the end of flood season,leading that the discharge decrease during non-flood season was larger than during flood season;(4)The water transfer reduced the inflow of reservoirs and increased the reservoirs operation extent,which would delay the process that water table rose to the flood control level during flood season,made the flood season runoff decrease;(5)Altogether,17 billion cubic meters of water transfer in upper reaches of the Yangtze River will have slight influence on the Three Georges Project(TGP)operating after all planning reservoirs are built up;the runoff at Yichang station reduced about 10% to its limit in April and reduced less only below 6% during flood season.