Impact of Climate Change on Runoff in the Huaihe River Basins

The assessment about future climate change on runoff of the Huaihe River Basins in China is focused. The Xin'anjiang monthly distributed hydrological model is used to simulate the past and future runoffs. The model is run with observed monthly precipitation and air temperature during 1961—2000 and the simulated runoff is verified with the corresponding hydrological observations.The verifications show that annual and monthly runoff are simulated well and the Nash efficiency coefficients range from 60% to 80% for the monthly simulations but above 80% for annual runoff at major hydrological stations such as Wangjiaba, Lutaizi and Bengbu.For runoff average in many years, the simulation is better.The correlation coefficient between simulations and observations reaches 0.99 and the mean absolute relative error is about 10%.The verified model is then forced with future climate scenarios based on three emission ones (B1, A2 and A1B) during 2011—2040 period from four coupled atmospheric and oceanic general circulation models to simulate future changes in the runoff.In the simulated future, the climate of Huaihe River Basins will be warmer and more humid compared with the climate of the base period of 1961—1990.Future annual runoff in the periods would have decreasing trends, which poses a challenge to the sustainable development of the Huaihe River Basins and water management of the East Route in the South-north Division Project.Monthly runoff would decrease in January and from July to December with high certainty and to increase during April to June with high uncertainty in most area of the Huaihe River Basin.During February and March, the monthly runoff would increase in the north of the Basin and to decrease in the south area to the stem of the Huaihe River as well as the Hongze Lake and the plain area of lower reaches of the Huaihe River.