Climate Change and Hydrological Response in the Watershed of Qinghai Lake

Qinghai Lake,the largest saline lake in West China,has experienced severe water shortage and water level decline in recent decades.This study intend to detect the climate change and hydrological response in the watershed of Qinghai Lake,using the data in terms of daily maximum,minimum and mean temperatures and daily precipitation from six meteorological stations as well as the hydrological records of annual lake water level,monthly runoffs of Buha river and Shaliu river in recent 50 years.Results showed that temperatures in the watershed presented an upward trend,with a maximum temperature rise of(0.29±0.17)℃ per decade(p0.05),and a minimum temperature rise of(0.55±0.5)℃ per decade (p0.05),and a mean temperature rise of(0.28±0.03)℃ per decade(p0.05).The annual mean temperature decreased with a rate of(-0.12±0.02)℃ per decade(p0.05).Climate warming in the watershed of Qinghai lake was faster than the global averages.The annual precipitation and maximum daily precipitation showed an insignificantly slight increase.The trends of raining days and dry days were spatially different.The water level of Qinghai lake decreased from 3196.55m in 1959 to(3 192.93m) in 2005,with a decrease rate of 7.8 cm per year(p0.01). Simultaneously,the coverage area of the lake decreased from(4 548.3) km~2 to(4 206) km~2,with a decrease rate of 7.4 km~2 per year(p0.01).The monthly runoff decreased significantly(p0.05) from December to next April for Buha river,and April to May for Shaliu river.Land use in Qinghai lake watershed is dominated by grassland,and agriculture and industry there is less developed.Land use change in the watershed in recent years was not obvious.Water level of the lake was mainly affected by the climate change.Pearson correlation analysis indicated that the annual mean temperature had a negative relationship with water level of Qinghai lake (R=-0.64,p=0.00),while the annual precipitation had a positive relationship with the change of lake water level(R=0.72,p=0.00),Buha river runoff(R=0.47,p=0.00),Shaliu river runoff(R=0.68,p=0.00) respectively.It is concluded that increased mean temperature contributed to the decline of water level of the lake,and the precipitation was responsible for the annual change of water level of the lake,runoff in Buha River and Shaliu River.With the global warming,the water level in Qinghai Lake possibly continues to decline.