变化环境下嘉陵江流域水循环及极端水文事件多尺度定量表达及预估

Under the changing environment, the water cycle process in the Jialing River Basin presents new changes and the frequency of extreme hydrological events increases, posing a great threat to social production and life. Therefore, it is urgent to carry out research on the interaction mechanism of water cycle transformation under the influence of climate change and human activities, and to explore the distribution patterns and evolution trends of water cycle elements and extreme hydrological events. The project aims to analyze the multi-scale evolution rules and spatial differentiation of the watershed water cycle and extreme hydrological events firstly. Then, Lasso regression, Budyko hydrothermal equilibrium equation and SWAT model were used to quantitatively assess the relative contributions of climate change and human activities to runoff and extreme hydrological events in different historical periods. At the same time, the multi-analysis, EOF decomposition method and orthogonal wavelet analysis method are used to analyze the formation of extreme floods and extreme dryness at different scales in different historical periods. Finally, deviation correction was performed on the ISI-MIP precipitation data using a statistical-dynamic combined downscaling method，and the water cycle and extreme hydrological event evolution prediction and multi-model comparison analysis were carried out under the 1.5°C and 2.0°C global warming targets. The research results will help to understand the multi-scale mechanism and evolution of water cycle and extreme hydrological events in a changing environment, and provide theoretical basis and scientific guidance for comprehensive water resources planning, flood control and drought warning in the Jialing River Basin.

变化环境下，嘉陵江流域水循环过程呈现出新的变化特征且极端水文事件发生频率增加，对社会生产和生活造成极大威胁。因此，亟待开展揭示气候和人类活动影响下流域水循环转化相互作用机理，探明各水循环要素及极端水文事件的分布格局及演变趋势的研究。本项目拟分析流域水循环和极端水文事件多尺度演变规律及其空间分异；运用Lasso回归法、Budyko方程和SWAT模型，定量评估气候变化和人类活动对径流和极端水文事件的相对贡献，同时，利用多元分析、EOF分解及正交小波分析法，辨识不同尺度极端水文事件的形成原因；进一步，利用统计-动力结合的降尺度方法，对ISI-MIP降水数据进行偏差校正，开展1.5℃、2.0℃升温情景下水循环及极端水文事件演变预估及多模型对比分析。研究成果有助于深入认识变化环境下水循环及极端水文事件的多尺度作用机理及演变规律，为嘉陵江流域水资源综合规划、洪涝干旱灾害预警提供理论依据和科学指导。

陵江流域由于特殊的水文、地理和气候条件，是我国淡水资源的重要来源区和西南部地区的生态屏障，该区域水循环过程的变化状况直接关系到我国西部地区的可持续发展，乃至长江中、下游地区的水环境和生态安全。受气候变化影响，嘉陵江流域气温逐年增加、蒸发增强、降水呈区域性变化，此外，人类活动极大的改变了下垫面条件，从而对水循环过程产生复杂的反馈效应。不同强迫要素的综合影响下，嘉陵江流域水循环转化要素呈现出复杂的变化特征，从短时间尺度看，各种极端气温、降水事件频发，造成不同强度洪涝、干旱灾害事件，从长时间尺度看，流域水热状况、水资源时空分布格局呈多维非线性特征，未来演变趋势不明。本项目首先，基于嘉陵江流域极端降水指数的绝对指标、相对指标、强度指标和持续指标，探明了嘉陵江流域各极端降水指数时空变化趋势，进一步分析了厄尔尼诺、印度洋偶极子及北极涛动对嘉陵江流域极端降水的遥相关影响。其次，基于标准化蒸发胁迫比SESR指数分析了嘉陵江的骤发干旱演变趋势，引入骤发干旱强度指数对骤发干旱进行等级划分，探明了嘉陵江流域骤发干旱强度时空演变趋势，进一步解析了降水和气温两个气候因子对骤发干旱时间演变趋势的影响。最后，基于1961-2014年的日降水量格点数据以及CMIP6多模式集合数据，采用分段三伽马分布对CMIP6数据进行偏差校正，并利用泰勒图以及多种评价指标来评估CMIP6多模式集合平均的模拟能力，进一步利用极端降水的四类指标来探究嘉陵江流域主要的极端降水模式（EEP）及其未来的变化特征。本研究对理解全球气候变化影响下嘉陵江流域极端降水时空演变特征以及制定未来嘉陵江流域农业生产布局规划有重要现实意义，同时，我国碳达峰碳中和政策正处于实施的重要时期，研究嘉陵江流域极端降水的时空变化特征及未来发展趋势，可以为该流域双碳目标的实施以及防洪减灾提供理论依据和支撑。