澜沧江源区气温与降水对径流变化的影响

Impact of temperature and precipitation on runoff change in the source region of Lancang River

为研究澜沧江源区水文气候变化特征,采用线性回归拟合分析方法、M-K非参数检验法对1960—2010年间澜沧江源区的水文气候变化趋势进行分析,计算了各季节气温变化对年气温变化的贡献量,并基于Pearson相关分析法和贡献率的计算讨论了降水量和气温对径流量变化的影响。结果表明:澜沧江源区年平均气温和各季节平均气温均呈显著上升趋势,其中,冬季的增温对年平均气温增加贡献最大(38%)。澜沧江流域源区年降水量无明显增减趋势,但春季降水量显著增加。澜沧江流域源区年径流量未呈现显著变化趋势,冬季和春季径流量呈现出显著的增加趋势。年际尺度上,径流量的主控因素是降水量,降水量对径流量年内变化的影响主要发生在降水相对丰沛的6—10月份;冬季和初春季节气温上升对径流量的改变存在一定的影响,且气温的贡献率要比降水的贡献率大,原因是气温升高加剧研究区内冰雪的消融,进而导致澜沧江源区的径流增加。

Based on the methods of linear regression, M-K and Pearson correlation analysis, the characteristics of the runoff change in the source region of Lancang River during 1960-2010 and its main influencing factors of temperature and precipitation were analyzed. Results show that there is a significant increasing trend of temperature in the source region of Lancang River and the winter temperature rise does the largest contribution(38%) to the annual increasing of temperature. The annual precipitation does not change significantly although there is a remarkable increasing trend of spring precipitation. The annual runoff in the study area exhibits no significant trend. However, both winter and spring runoff increase significantly. Correlation analysis shows that precipitation is the main controlling factor for the annual runoff. Monthly runoff change is also dominated by precipitation during the period with plentiful rainfall from June to October. However, the temperature has an important influence on runoff change during early spring and winter, which is attributed to the increasing temperature causing the accelerated melting of ice and snow. The quantitative analysis indicates that temperature has a larger contribution rate to runoff change than that of precipitation within early spring and winter.