气候变化下中国主要流域气象水文干旱潜在风险传播

Risk propagation from meteorological to hydrological droughts in a changing climate for main catchments in China

  • 摘要: 全球气候变化影响了气象水文要素的时空分布特性,气象水文干旱事件的转化关系及风险传播特征亟待研究。基于站点、栅格观测资料和CMIP5(Coupled Model Inter-comparison Project Phase5)的19个气候模式输出数据,采用新安江等4个水文模型模拟了中国135个流域历史(1961—2005年)和未来时期(2011—2055年,2056—2100年)的水文过程,计算了SPI(Standard Precipitation Index)和SRI(Standard Runoff Index)干旱指标,通过游程理论识别了气象干旱与水文干旱事件,利用Copula函数与最大可能权函数度量二维干旱风险特征,定量评估了气象干旱至水文干旱的潜在风险传播特性。结果表明:①气象-水文干旱对气候变化响应强烈,华北和东北地区的干旱联合重现期增大,干旱潜在风险减小,华中和华南地区的干旱联合重现期减少60%~80%,干旱潜在风险增加;②气象干旱与水文干旱风险在历史和未来时段均存在显著的正相关关系,相关系数超过0.99;③各流域水文干旱风险变化对气象干旱风险变化的敏感程度不会随气候变暖发生较大变化,但未来北方地区水文干旱同气象干旱同时发生的概率将会小幅度增加。

     

    Abstract: Global climate change has altered the spatial-temporal regimes of hydro-meteorological variables. The impact of climate change on the risk transferability from meteorological to hydrological droughts needs to be investigated. Based on the gridded meteorological data and 19 global climate model simulations from the Coupled Model Inter-comparison Project Phase 5, the climate change scenarios were generated over 135 catchments in China for two future periods (2011—2055 and 2056—2100). The best performed hydrological model over four lumped models was selected for hydrological simulations. Based on precipitation scenarios and hydrological simulations, the Standard Precipitation Index (SPI) and the Standard Runoff Index (SRI) were respectively calculated for each catchment and time period. The meteorological and hydrological drought episodes were extracted based on the runoff theory. Finally, drought risks by incorporating the most likely selection into the Copula function were calculated, and the risk transferability from meteorological to hydrological droughts under the current and future climates were investigated. The results show that: ① Meteorological and hydrological droughts are highly sensitive to future warming climates. Specifically, drought return periods are projected to lengthen in northern China, indicating mitigating risks, while they become shortened by 2 to 5 times over most catchments in central and southern China, indicating deteriorated conditions. ② The meteorological drought risks positively correlate with the hydrological drought risks under the current and future climates, with the Pearson correlation coefficients being higher than 0.99. ③ The sensitivity of hydrological to meteorological drought risks almost stay unchanged for each catchments for different future periods, whereas the co-occurrence of hydrological and meteorological droughts is projected to slightly increase over northern China under future warming climates.

     

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