长江上游保护区径流变化特征及其对气候因子响应的区域差异性研究

分析河川径流的演化规律和动因,对于变化环境下的水生态环境和水资源适应性规划管理十分重要。以长江上游保护区屏山、朱沱和赤水站的1956—1990年的近自然状态径流为研究对象,分别利用小波分析方法、非参数Mann-Kendall趋势分析方法和弹性系数方法,探究了径流变化的多时间尺度演变特性、变化趋势和径流变化对气候因子的响应状况。结果表明:3个研究站点的年径流周期性变化存在相似性,都有着10~14 a的丰枯震荡周期。各站点的径流在年和季节尺度上呈现增加的趋势,但在月尺度上,屏山和朱沱站情况相似,在8月份径流存在明显的下降趋势,赤水站径流在3,4月份有显著增加。3个站点的径流都对降雨的敏感度较高,但是各站点年径流对气候因子的响应也存在区域差异性,流经区域大多位于高山峡谷的屏山站和赤水站,其年径流对降雨的弹性系数要大于朱沱站,而位于四川盆地区域的朱沱站的年径流对蒸发的弹性系数要稍微大于屏山和赤水站。

Runoff Changes and Its Regional Differences in Response to Climate Factors in Reserve Zone of the Yangtze River Upstream Area

Analysing the regularity and causes of runoff evolution in changing environment is critical to the adaptive planning and management of water eco-environment and water resources.According to the natural runoff of 1956-1990 at Pingshan,Zhutuo and Chishui stations in reserve zone of the Yangtze River upstream area,the evolution characteristics and change trends of runoff and its responses to climate factors were explored by using wavelet analy-sis method,nonparametric Mann-Kendall trend test method and climate elasticity of streamflow.The analysis results showed that annual runoff of the three stations had a periodic similarity with an oscillation cycle of 10-14 years.At yearly and seasonal scales,runoff of the three stations showed increasing trends.At monthly scale,Pingshan and Zhutuo had a similarity with an obvious decline trend in August,whereas Chishui station had a significant increase trend in March and April.Climate elasticity of precipitation of the three stations was larger than climate elasticity of evaporation.However,the responses of annual runoff to climate factors at the three stations also had regional differ-ences.Climate elasticity of precipitation of Pingshan and Chishui stations which flow through valley and mountain areas was larger than that of Zhutuo station;while climate elasticity of evaporation at Zhutuo station which located in Sichuan basin was slightly bigger than that of Pingshan and Chishui stations.