变化环境下江河源区水文水资源效应问题已成为国内外水科学领域的研究热点。为了探究长江源径流演变及其原因,在分析长江源径流演变特征的基础上,探讨了地面气象因子和大气环流因子对径流的影响。结果表明:长江源区直门达站径流年内分配不均,年径流有显著上升趋势;1956—2016年径流系列在2004年发生突变,具有23~24 a和42~43 a的显著周期,42~43 a的周期项具有最大波动能量;降水量是径流变化的主导因素,水面蒸发量是径流变化的重要影响因素,但气温影响径流的变化不显著;直门达站月流量对青藏高原指数(TPI_B)有很好的响应,青藏高原低涡与降水的空间分布和暴雨量级相吻合。研究成果可为长江源水资源管理部门决策提供参考。

Evolution of hydrological cycle and water resources has been a hot topic for scholars and researchers around the world. This holds even more true in water source areas under changing environments. In this paper, the evolution characteristics of runoff in source regions of Yangtze River were investigated using statistical methods. On this basis, the impacts of both surface meteorological factors and upper atmospheric circulation factors on runoff were evaluated. Results show that runoff at Zhimenda station in the headwaters of Yangtze River distributed unevenly during a year, and a significant increasing trend is observed with regard to annual runoff. An obvious abrupt change in the year of 2004 was observed for runoff time series from 1956 to 2016. Wavelet analysis indicated that there were two significant periods of these time series, which were 7-8 years and 20-21 years, respectively. The biggest power of the spectrum was observed in the 42-43 year period. As for the impacts of different meteorological and atmospheric factors on runoff, our study indicated that precipitation was the leading driving force for runoff variation, and the role of water surface evaporation was also important.The variation of runoff was also influence by air temperature, but the effect was not significant enough. There was good agreement between monthly runoff observations of Zhimenda station and the Tibetan Plateau Index_B (TPI_B). Both the spatial distribution and magnitude of precipitation agreed well with the Tibetan Plateau vortex.