怒江流域云南区段降雨时空变化分析

利用怒江流域云南区段及其毗邻地区77个站点1980~2009年雨量资料,以及怒江干流道街坝站1957~2015年和南汀河支流姑老河站1960~2015年降雨、径流资料,研究该流域降雨区域分异特征及变化趋势。结果表明:怒江流域云南区段多年平均面雨量达1 336.7 mm,远大于全省平均降雨量;怒江干流云南区段上游贡山地区和下游支流苏帕河流域,以及支流南汀河流域下游多年平均降雨量达1 500 mm以上,而干流的中游怒江坝干热河谷不足1 000 mm,降水空间分布格局与西南季风强弱及纵向岭谷地形密切相关;怒江流域云南区段降水量呈下降趋势,与怒江上游西藏区域相反,支流南汀河流域面雨量减少速率(56 mm/10 a)大于怒江干流云南区段(29 mm/10 a);怒江流域云南区段夏季降水占全年降水量的51%,怒江干流云南区段与支流南汀河流域降水量差异主要表现在夏季;怒江流域云南区段春季降水量呈增加趋势,夏季、秋季和冬季降水量呈减少趋势;怒江干流道街坝站、支流南汀河姑老河站降雨量长周期分别为36 a和33 a左右,从降雨变化长周期来看,2002年以来的少水期将持续到2018~2020年。怒江干流云南区段降水量变化的Hurst指数值为0.69,表明其未来趋势与过去一致,仍将延续降水量减少的变化趋势。

Analysis of temporal and spatial variation of rainfall in Yunnan Province of Nujiang River Basin

To analyze the regional differentiation characteristics and variation trend of rainfall in Yunnan Province of the Nujiang River Basin, we analyzed the rainfall data from 77 precipitation stations in Yunnan Province in Nujiang River Basin and the adjacent regions during the period of 1980 to 2009 and rainfall and runoff data at Daojieba hydrometric station on the main stem of the Nujiang River basin from 1957 to 2015 and Gulaohe hydrometric station on its tributary of Nanting River from 1960 to 2015. The results show that the average annual areal rainfall is 1336.7 mm in the study area, which is far more than the areal rainfall in the whole province. The average annual areal rainfall is over 1500 mm in Gongshan mountain area in the upstream of the main stream basin, the downstream areas of tributary the Supa River and the Nanting River, while the rainfall in dry-hot Lujiangba Valley in the middle reach of the main Nujiang River stream is below 1000 mm, showing that the rainfall spatial distribution pattern is closely related to the southwest monsoon intensity and the terrain of longitudinal range-gorge region. The rainfall has a decreasing trend in Yunnan Province of the Nujiang River Basin , which is opposite to the upper Tibet area; the areal rainfall decreasing trend (56mm/10a) in tributary Nanting River Basin is greater than that in Yunnan Province (29mm/10a) of the Nujiang River Basin. The precipitation in summer accounts for 51% of annual precipitation in Yunnan Province of the Nujiang River, and the difference between Yunnan Province of the Nujiang River Basin and the tributary Nanting River Basin is mainly in summer. The rainfall has an increasing trend in spring in the study area, but it has a decreasing trend in summer, autumn and winter. The long period of rainfall at Daojieba hydrometric station and Gulaohe hydrometric station are about 36 years and 33 years, respectively. From the perspective of the long period of rainfall, the low rainfall period since 2002 will continue until 2018 to 2020. The Hurst index is 0.69 for rainfall variation in Yunnan Province of the main Nujiang River stem, which implies that the rainfall would keep on a decreasing trend in the future.