Climate Change of the Longitudinal Range-Gorge in Yunnan and Its Influence on the River Flow
云南纵向岭谷地区气候变化对河流径流量的影响

Based on the observed data of the flow in the longitudinal range-gorge region and the data of monthly precipitation and air temperature field in Yunnan, and using the statistics and wavelet transforms, the interannual climate change under the effect of the longitudinal range-gorge and its influence on the international river flows are investigated. The results show that the latitude variations of the high correlation centers between the monthly precipitation field and the international river flows are not significant due to the role of special underlying surface in the longitudinal range-gorge region, but the longitude variations are very significant. The annual precipitation of the Lancang climatic region is obviously greater than that of the eastern Lixian River and Yuan River regions, but the standard deviation of the annual precipitation is significantly smaller than them. The annual mean air temperature of the Yuan River region is lower than that of the western Lixian River and Lancang River regions, and the standard deviation of the annual air temperature is also smaller than them. Corresponding to the characteristics of the annual precipitation variations under the effect of the longitudinal range-gorge, the standard deviation of the annual flows of the Yuan River is also obviously greater than western Lixian and Lancang rivers. The barrier action of longitudinal range-gorge on southwest monsoon is greater, but on northeast monsoon is smaller. The annual precipitation variations under the effect of the longitudinal range-gorge are mainly on the smaller time scale, with the increase of time scale, the effect of the longitudinal range-gorge becomes smaller. The role of the longitudinal range-gorge in the annual air temperature variations is smaller than the annual precipitation variations. In recent years, the main characteristics of the annual precipitation variations in all the climatic regions are that precipitation tends to increase, under such an effect, the annual flow variations for the international rivers also tend to be great.