青海湖流域气候变化及其水文效应

Climate Change and Hydrological Response in the Watershed of Qinghai Lake

利用青海湖流域内及周边6个气象站近50年来的逐日最高、最低、平均气温和降水量，青海湖水位、面积以及沙柳河和布哈河逐月径流资料分析了该流域的气候变化及其水文效应。结论认为：青海湖流域近年来最高气温以（0．29±0．17）℃／10年的速度增加（P〉0．05），最低气温以（0．55±0．5）℃／10年的速度显著增加（p〈0．05），平均气温以（0．28±0．03）℃，10年的速度显著增加（P〈0．05），同时，年平均温差以（-0．12±0．02）℃，10年的速度显著减少（P〈0．05）。与全球气候变暖相比，青海湖流域气温升高的速度更快。流域各站年降水量和日最大降水量呈增加趋势（P〉0．05），降水天数和干旱期变化差异性较大。青海湖水位和面积分别以7．8cnd年和7．4km^2，年的速度显著下降（P〈0．01）。沙柳河、布哈河年径流量呈略微减少趋势（P〉0．1），而且分别在4月～5月和12至次年4月减少趋势显著（P〈0．05）。气候变化和水文效应相关分析表明，青海湖水位与流域平均气温呈显著负相关（P〈0．01），而水位变化量、沙柳河和布哈河径流量与降水量呈显著正相关（P〈0．01）。

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 （p 〉 0.05）, and a minimum temperature rise of （0.55 ± 0.5）℃ per decade （p 〈 0.05）, and a mean temperature rise of （0.28 ± 0.03） ℃ per decade （p 〈 0.05）. The annual mean temperature decreased with a rate of （ - 0.12 ± 0.02）℃ per decade （p 〈 0.05）. 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（p 〈 0.01 ）. 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 （p 〈 0.01 ）. The monthly runoff decreased significantly（p 〈 0.05） 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.