1956—2011年金沙江下游梯级水电开发区降水变化特征分析

Analysis of characteristics of precipitation variation in cascade hydropower development zone in lower reaches of Jinsha River during period from 1956 to 2011

基于金沙江下游梯级水电开发区10个气象站1956-2011年的逐月降水资料，运用线性倾向估计法、Morlet 小波分析法和 R/ S 分析法对多年降水和季节降水变化及其趋势、周期和持续性特征进行分析。结果表明：研究区1956-2011年降水量呈波动式下降趋势，降水倾向率为-1.338 mm/ a；季节降水中除春季呈微小上升趋势外，夏、秋和冬季均呈下降趋势，且空间差异明显；夏、秋季的降水量占全年的81.1%，尤以夏季为主导，占57.4%；年降水存在1～2 a、4 a 、8 a 、14 a和31 a 的周期变化规律，其中8 a 的周期尤为明显，通过90%置信水平检验；研究区降水序列总体上存在明显的 Hurst 现象，具有持续性特征，未来降水仍会维持减少趋势。

This study focused on the spatio-temporal variation of precipitation in the cascade hydropower development zone in the lower reaches of the Jinsha River. The changing trends, periodic oscillation, and duration characteristics of multi-annual and seasonal precipitation were analyzed using linear trend analysis, Morlet wavelet analysis, and R/ S analysis methods, based on monthly precipitation data of ten meteorological stations in the study area during the period from 1956 to 2011. The results show that the annual precipitation in the study area during the period from 1956 to 2011 has shown a fluctuant downward trend at a tendency rate of -1. 338 mm per year. The precipitation increased slightly in spring and decreased in summer, autumn, and winter, with significant spatial differences. The precipitation in summer and autumn accounted for 81. 1% of the annual precipitation, especially the precipitation in summer, which was the leading factor accounting for 57. 4% of the annual precipitation. The periodic oscillation of annual precipitation was concentrated in one to two years, expectant four years, eight years, 14 years, and 31 years, and especially in expectant eight years, which was verified by a 90% confidence level test. There was an obvious Hurst effect of the precipitation series in the study area, with a feature of persistence in general, and the precipitation will maintain a decreasing trend in the future.