基于新型综合干旱指数的珠江流域未来干旱变化特征研究

综合干旱指数构建及评估未来综合干旱特征变化具有重要的理论价值和现实意义。本文基于Copula函数,联合降水及VIC模型模拟的蒸散发、径流和土壤水等水文气象要素,构建了一种能综合表征气象-水文-农业干旱特征的新型综合干旱指数(CSDI),并以珠江流域为例进行应用,分析了未来气候变化情景下研究区综合干旱的变化特征。结果表明:(1)CSDI指数综合考虑了与干旱发生、演变密切相关的水文气象要素,能很好地监测到干旱的发生、发展过程,可综合从气象、水文与农业等角度刻画干旱特征。(2)RCP2.6情景下,流域下游综合干旱严重性降低且历时减少,而RCP4.5和RCP8.5情景下,全流域则均增加,严重性和历时分别至少平均增加14.8%和11.5%。(3)RCP2.6情景下,流域上下游超阈联合重现期100年的同频设计严重性和历时值均大幅降低,而RCP4.5、RCP8.5情景下,流域大部分地区则均呈升高。本研究可为研究区防旱抗旱提供新的参考。

Changes of drought characteristics in future in Pearl River Basin describing by a new comprehensive standardized drought index

Developing a comprehensive standardized drought index has significantly academic and realistic value. Utilizing Copula function,a new comprehensive standardized drought index (CSDI),which can simultaneously monitor meteorological, hydrological and agricultural features of a drought process, was developed by combining hydrometeorological factors such as precipitation evapotranspiration,and runoff and soil moisture. Taking the Pearl River Basin (PRB) as an example, the changes of comprehensive drought in future scenarios were analyzed. The results show that:(1) Good correlation (P < 0.01) between CSDI and standardized precipitation evapotranspiration index (SPEI)/standardized runoff index (SRI)/self-calibrating Palmer drought severity index are observed,and it includes the advantages of these three drought indices to represent different droughts. The CSDI can well monitor drought beginning,duration and end. (2) In the RCP 2.6 scenario (2050-2100), the comprehensive drought severity and duration in the PRB will decrease by 4.2% and 3.5% respectively,compared with the historical period. However,in the RCP 4.5 and 8.5 scenarios,they increase by 15.3% and 11.5% respectively. (3) In the RCP2.6 scenario,when the joint return period exceeds the threshold by 100 years, the designed drought severity and duration in the PRB will decrease by 13.5% and 6.5% respectively, while in the RCP4.5 and 8.5 scenarios, they increase by 20.5% and 22.1% respectively.