基于SPEI和SDI指数的云南红河流域气象水文干旱演变分析

本文基于红河流域43个气象站1961-2012年逐月降水、气温数据以及干支流2个水文站1956-2013年逐月流量数据,采用标准化降水蒸散指数(SPEI)和径流干旱指数(SDI)分析流域气象水文干旱的演变特征,并探讨水文干旱对气象干旱的响应。结果表明：①1961-2012年期间,流域总体上表现出干旱化的趋势,季节变化上春季有变湿的趋势,而夏、秋、冬三季有变干的趋势,但趋势并不显著。干旱频率季节空间分布差异较大,春旱和冬旱发生频率较高。从干旱范围来看,春旱范围呈缩小的趋势,夏旱、秋旱和冬旱范围表现出不同程度的增大趋势;②1956-2013年期间,流域水文干旱表现出加剧的趋势,其中1958-1963、1975-1982、1987-1993、2003-2006和2009-2013年为水文干旱多发期,近10年来频率明显增加;③流域水文干旱滞后于气象干旱1~8个月,气象和水文干旱事件的干旱历时、严重程度和强度之间具有紧密的相关性,流域气象干旱是水文干旱的主要驱动力。

Hydrological and meteorological droughts in the Red River Basin of Yunnan Province based on SPEI and SDI Indices

Based on the monthly precipitation and temperature data from 1961-2012 at 43 meteorological stations and discharge data from 1956-2013 at two hydrological stations on the Red River, we analyzed the variation of hydrological and meteorological droughts by using Standard Precipitation Evapotranspiration Index (SPEI) and Streamflow Drought Index (SDI). The results show that: (1) Meteorological droughts presented an increasing trend at the annual scale in 1961-2012. At the seasonal scale, a wetting trend was detected in the spring in most areas, and a drying trend was observed in the summer, the autumn, and the winter seasons. Regional differences have been found in seasonal drought frequency, and high frequency droughts occurred in the spring and the winter. The influence areas of drought decreased in the spring. In contrast, increased trend was found in the summer, the autumn, and the winter. (2) Hydrological drought indicated an increasing trend in 1956-2013. There were more hydrological droughts during 1958-1963, 1975-1982, 1987-1993, 2003-2006, and 2009-2013. Hydrological droughts occurred most frequently in the last decade. (3) Analysis of the relationship between meteorological and hydrological drought indices shows that the occurrence of a hydrological drought event lagged a meteorological drought event by a variation of 1 to 8 months. The duration, magnitude, and intensity of meteorological droughts were well close to the characteristics of hydrological drought events. The most important factor that caused hydrological drought in the Red River Basin was meteorological drought.