西南河源区径流演变规律分析

Variation characteristics analysis of runoff in river source regions of southwest China

为了研究西南河源区径流变化的区域一致性和差异性规律,本文利用西南河源区6个水文站近50年的日径流资料以及西南河源区地面气温和降水月值0.5°×0.5°格点数据,通过线性倾向估计、累积距平、Mann-Kendall突变诊断、t检验等方法,分析西南河源区20世纪下半叶到21世纪初的年径流演变规律和径流对气候要素的响应。结果表明:西南河源区大部分站点年径流呈下降趋势,但变化趋势不明显。其中在20世纪60年代初,河源区年径流总体有小幅的上升;20世纪70年代一直到20世纪末,年径流一直呈下降趋势;21世纪以来,年径流有所回升;河源区西北部和东南部的径流突变主要发生在20世纪60年代中期和20世纪末21世纪初,在两处突变点之后径流分别呈下降和上升的趋势;河源区径流主要受降水和气温的影响,其中降水的影响较大。

In order to study the regional consistency and difference of runoff variation in source re- gions of southwest China, in this paper, the variation characteristics of runoff changed with year from the later half of the 20th century to the early 21st century and reactions to climate change that cause runoff evolution were analyzed based on the daily runoff data over the past 50 years of the six hydrological stations and ground daily precipitation and temperature data at 295 grids with the spatial resolutions of 0. 5°×0.5° over source regions of southwest China by trend analysis and abrupt change test. Negative trends are found in most sites of source regions over the past 50 years for annual runoff, but the trend is not obvious. In the early 1960s, the annual runoff in source regions exhibit an increasing trend in general; from the 1970s to the end of the 20th centu- ry, the annual runoff displays a continuous negative trend, representing a potential positive tend- ency since the 21st century. The abrupt change of annual runoff of northwest source regions oc- curred mainly in mid-1960s, after which the annual runoff shows decrease trends, whereas the abrupt change of annual runoff of southeast source regions mainly happened from the end of 20th century to the early 21st century with the annual runoff representing an increasing trend subse- quently. The precipitation and temperature effect upon the annual runoff of source regions of southwest China cannot be ignored, with precipitation is the main influencing factor.