Abstract:

The West Works in SouthtoNorth Water Diversion Project is an important transbasin water diversion project to divert water from the upstream main stream and tributaries of the Yangze River (referred as source area) to upstream of the Yellow River (referred as target area). In the West Route Works, dams shall be constructed on the Jinsha River, which is the main stream of the Yangze River, the Yalong River and the Dadu River which are the tributaries of the Yangze River, with the dam sites at El. 3 000-4 000 m, and water is diverted to the upstream of the Yellow River by diversion tunnels through the Bayankala Mountain which is the divide between the Yangze River and the Yellow River, with the diverted water amount of 8 billion m3, 645 billion m3, and 255 billion m3 respectively, annual totaling 17 billion m3. This can compensate for the insufficiency of the Yellow River water resources and resolve the water resources shortage problems. Because of large water diversion amount, long diversion route, many water source points, difficult construction, remarkable benefit, etc., the West Route Works in SouthtoNorth Water Diversion Project is regarded as the greatest transbasin water diversion works in the world.The source area is located in the southeast of QinghaiXizang Plateau at north latitude 31°30′-35 ° 30′ and east longitude 90°30′-103°30′, including the areas upstream of Zhimenda on the Tongtian River (Jinsha River), area upstream of Ganzi and Daofu on the Yalong River, and area upstream of Zumuzu and Zhuosijia on the Dadu River, with a total area of 220 000 km2. This area is at El. 3 000-4 500 m, with the daily mean air temperature below 0°for a period of 5-8 months in a year.Based on the runoff, precipitation, temperature and sunshine duration series of 5 hydrological stations and corresponding meteorological stations in West route of SouthtoNorth water Diversion Project over the past 50 years, significant autocorrelations at a 5% level in series were identified and removed by the PreWhiten method. The MannKendall test was used to detect trends and abrupt change, which were validated by the Spearman test and Double Mass Curve technique. Moreover, the 〖JP2〗Pearson method was applied to analyze the correlations between runoff and various climatic factors. The results indicated that in the recent 50 years, the runoff does not change obviously，but in the past decade, it has a further decreased trend except Zhimenda. Precipitation and sunshine have no obviously trend, in contrast, the temperature increases significantly. On the whole, runoff is mainly affected by climate change and the changes of runoff in future need a comprehensive study on spatial and temporal distribution of temperature, precipitation, runoff, glaciers, etc