流域极端水文事件对气候变化的多维响应及预估研究

The impact of climate change on extreme hydrologic events, are influenced by many factors on different temporal and spatial scales such as climate cycle, hydrological process, human activities, land surface condition and so on. The impacts show multi-dimensional and nonlinear characteristics. On the one hand, for the short time scale, increase of extreme climate events is easy to cause the frequent occurrence of floods and droughts. On the other hand, for the longer time scale, changes of climate averages will aggravate the intensity and duration of extreme hydrological events. The Jiajingjiang River basin is selected as the research area, which is an important tributary of the upper Yangtze River basin. Floods and droughts are very often in the research area and are mostly driven by climate change. To study the impact form, scope and extent of climate change on extreme hydrological events at different time scales, the temporal and spatial characteristics of different extreme climate and hydrological variables on multi time scales are firstly analyzed in the Jialingjiang River basin. Some mathematical models and functions are then set up to reflect the relationships between changes of climate and responses of extreme hydrological events, including changes of climate extremes and climate averages. The multi-dimensional influence mechanisms of climate extremes and averages on frequency, intensity, quantities, and duration of extreme hydrological events are explored in the basin. Finally, future temporal and spatial evolution patterns of extreme hydrological events under the latest green gas emission scenarios are projected in the Jialingjiang River basin. The project contributes to the understanding of the interaction between atmosphere and hydrosphere, and promotes the development of climate and hydrology inter-disciplinary research, and provides scientific basis for the integrated water resources allocation.

气候变化对流域极端水文事件的影响，受不同时空尺度上气候循环、水文过程、人类活动、下垫面等多因素影响，呈现多维非线性特征，既表现在短时间尺度上极端气候事件异常增多极易引发流域洪水和干旱事件频繁发生，也表现在长时间尺度上气候均值变化将加剧极端水文事件的强度和持续时间等。本项目以流域洪旱灾害频繁且主要受气候变化驱动的长江上游重要支流-嘉陵江流域为例，研究不同时间尺度上气候变化对极端水文事件的影响形式、范围与程度，分析多时间尺度上气候要素与水文极端指标的时空变化特征，构建反映流域气候极值和均值变化与极端水文事件典型指标响应的数学模型及函数，解析流域极端水文事件频率、强度、总量、历时等对气候变化的多维响应机制，并预估流域极端水文事件在最新一代温室气体排放情景下的时空演化格局。项目有助于认识大气圈与水圈之间相互作用机理、促进气候与水文交叉学科发展，并为流域水资源综合配置提供科学依据。

气候变化对流域极端水文事件的影响，受不同时空尺度上气候循环、水文过程、 人类活动、下垫面等多因素影响，呈现多维非线性特征，既表现在短时间尺度上极端气候事件异常增多极易引发流域洪水和干旱事件频繁发生，也表现在长时间尺度上气候均值变化将加剧极端水文事件的强度和持续时间等。本项目以流域洪旱灾害频繁且主要受气候变化驱动的长江上游重要支流—嘉陵江流域为例，研究不同时间尺度上气候变化对极端水文事件的影响机理，分析多时间尺度上气候要素与水文极端指标的时空变化特征，构建反映日尺度上流域气候要素与水文过程响应的分布式水文模型，解析流域极端水文事件的频率、变化特征，并预估流域极端水文事件在新一代温室气体排放情景下的时空演化格局。研究表明，嘉陵江流域在1971-2010年期间出现两次较为严重的干旱事件，且随着时间推移，干旱的情况仍可能加剧，发生频率也可能会有所增加。采用VIC分布式水文模型在长江上游模拟流域水文过程，并预估在不同温室气体排放情景下的水文响应可以得到，年平均流量、汛期流量和年内高流量值将在21世纪呈增加趋势。而且，随着排放量的增加，区域极端水文事件也呈现频率加快、强度增强的趋势。其中，分析流域气象水文演变规律的实测站点数据、区域水文过程预估涉及到的全球气候模式在不同温室气体排放情景下的气候预估和水文模型模拟数据是关键数据。本项目可为辨析气候变化和人类活动对水文过程的影响提供科学依据，有助于认识大气圈与水圈之间相互作用机理、促进气候与水文交叉学科发展，并为流域水资源综合配置提供科学依据。