Climate Change in Upper Yellow River in Recent Years and its Effect on Inflow of Longyangxia Reservoir

摘要

Distribution laws and variation characteristics of precipitation and temperature in the area above Longyangxia Reservoir on upper Yellow River were analyzed firstly with climate data from 1956 ～ 2004. Based on the correlation relationships between natural runoff at Tangnaihai Station and temperature, precipitation at each gauging station in the upper Yellow River, natural runoff calculation formula was established. In further, impacts of climate change in 1990s on inflow Longyangxia Reservoir, sensitivity of runoff to climate change at Tangnaihai Station were studied. Results show that: ① Average annual temperature abover Tangnaihai in 1990s is 0.5℃ higher than perennial average value, and 0.7 ～ 0.8 degree higher than that in previous decades. Precipitation in 1990s is less than perennial average value, and meanwhile, that is much less than rainfall in previous decades; especially in Maqu district, the maximum annual reduction is up to 15.8% , and the reduction in flood seasons from June to September is beyond 11% . ② Natural annual runoff in 1990s decreases 43.7 x 10~8 m~3 compared to that in previous period, and 20.2% of that was caused by climate change. ③ Responses of runoff to changes in precipitation are much more obvious than that to changes in temperature.