金沙江流域近50年气象水文干旱时空变化特征

Spatiotemporal variation of hydro-meteorological drought in Jinsha River Basin in recent 50 years

通过构建SWAT模型,模拟得到了金沙江流域21个子流域的径流序列,并对3个月尺度标准化降水指数(SPI3)、标准化降水蒸散指数(SPEI3)和标准化径流指数(SRI3)序列的变化趋势和周期进行了分析,同时还对SRI3序列进行了干旱事件识别分析。分析结果表明:①1968~2017年,金沙江流域15个子流域的年径流总体呈现显著增加的趋势;②分别有10个子流域的SPI3、12个子流域的SPEI3和19个子流域的SRI3总体呈现为显著增大的趋势;③水文干旱事件共479次,但多数历时较短、强度较小;④全流域水文干旱最严重的时期为1968~1977年,且其年内分布不均匀,夏秋季节易于发生水文干旱并在秋冬季节最为严重,其中金沙江干流全段和雅砻江中上段的干旱情势相比其他区域更为严重。

This study investigates the spatiotemporal variation of hydro-meteorological droughts in the Jinsha River Basin during 1968-2017. The entire basin was divided into 21 sub-basins, and the Soil and Water Assessment Tool model(SWAT) was employed to simulate the monthly runoff of each sub-basin. Then, the 3-month Standardized Precipitation Index(SPI3), Standardized Precipitation Evapotranspiration Index(SPEI3) and Standard Runoff Index(SRI3) were used to quantify the drought characteristics. The tendency and periodicity of these indices were investigated using Mann-Kendall test and Wavelet Analysis method, and the spatiotemporal variation of drought was analyzed based on the drought events identified by SRI3. The results show that: ① The annual runoff of 15 sub-basins during 1968-2017 showed an increase tendency. ② The trends of 10 sub-basins’ SPI3, 12 sub-basins’ SPEI3, and 19 sub-basins’ SRI3 increased significantly. ③ The total occurrence of hydrological drought events in the whole basin was 479 times, but most of them had short duration and low intensity. ④ The most severe hydrological occurred during 1968-1977;the temporal distribution of hydrological droughts was uneven for different seasons, i.e. hydrological droughts were more frequent in summer and autumn and more serious in autumn and winter. The mainstream of the Jinsha River and the upper and middle reaches of the Yalong River suffered more serious drought than other regions.