雅鲁藏布江中游地区气候要素变化及径流的响应

Changes in climate and runoff in the middle course area of the Yarlung Zangbo River Basin

基于1956-2010年雅鲁藏布江流域中游及周边17个气象站逐日降水、气温数据,以及拉孜和羊村水文站逐月天然径流资料,采用小波分析、相关分析及多元线性回归等方法,定量分析了径流与气候要素变化特征及其响应关系。研究表明:1研究区增温趋势明显,平均增温速率为0.31℃/10a,径流的变化趋势与降水高度一致,均表现出增加→减少→增加→减少的波动规律;2年径流量与降水量均存在6.0~6.5a和15.5~16.5a的变化周期,而气温变化周期性稍差;3降水是研究区年径流变化最主要的控制因素,年径流量与年降水量的相关系数达0.89;但气温和降水同时影响着径流年内分配过程,且径流响应具有一定滞后性;44-9月降水量的丰枯决定着径流量变化,径流系数小于1.0;其它月份则以非降水补给为主,径流系数远大于1.0,年径流系数呈下降趋势,非降水补给因素对径流的影响在逐渐增强。

Based on monthly data for precipitation,air temperature and runoff in and around the middle course area of the Yarlung Zangbo River Basin from 1956 to 2010,changes and runoff responses were analyzed quantitatively using wavelet analysis,correlation analysis,and multiple linear regression. We found that warming is obvious in the study area,showing that the average rate of warming is 0.31°C/10 a. Trends in precipitation and runoff are highly consistent,showing a fluctuation of increase-reduce-increase-reduce. The periodic change in interval runoff and precipitation maintains a high level of consistency and at two scales of 6.0~6.5a and 15.5~16.5a,however,temperature change periodicity is weak. Precipitation is the most dominant factor controlling changes in annual runoff and the correlation coefficient was 0.89 between precipitation and runoff;however,both air temperature and precipitation are impacting runoff processes within a year,and the runoff response shows hysteresis. Generally,runoff is the result of precipitation from June to November,and air temperature has a positive effect on runoff in other periods. The magnitude of precipitation determines runoff from April to September,and as a result the runoff coefficient is below 1.0. In contrast,the runoff coefficient is much larger than 1.0 during other months because river feeding takes place,rather than precipitation. With climate warming and wetting,the runoff coefficient is gradually decreasing,indicating that the influence of factors other than precipitation on runoff is increasing in the area.