澜沧江-湄公河流域极端水文事件模拟与预估研究

深入研究全球增暖背景下洪水/干旱等极端水文事件的形成过程及其演变规律，对于有效应对气候变化、科学防范自然灾害具有重大的意义。大尺度陆面水文模型是开展气候变化下极端水文事件模拟预估的重要工具。然而，目前陆面水文模型多采用传统的河网汇流方案，缺乏对较高精度的大尺度洪水演进及其淹没过程的模拟能力，难以用于气候变化下水灾害风险评估。本项目拟改进陆面水文模型的汇流演算方案，发展耦合水动力学汇流模型的大尺度极端水文事件模拟模型，阐明汇流演算对极端水文模拟的影响机制；以澜沧江-湄公河流域为研究区，构建耦合第六次国际耦合模式比较计划（CMIP6）新一代气候模式与大尺度极端水文事件模拟模型的多模式集合预估框架，揭示全球增暖对澜沧江-湄公河流域未来极端水文事件及其风险的影响。本项目成果不仅为全球变化背景下水灾害影响评估提供理论基础与实践工具，还为澜沧江-湄公河流域制定气候变化应对措施提供科学依据。

To understand the inherent schemes and predict changes in hydrological extremes (e.g., drought and flood) under global warming is of great significance for risk response and climate change adaptation. Large-scale land surface hydrological model (LSM) is an important tool for assessing the impacts of climate change on hydrological extremes. However, the routing scheme in LSMs is mostly based on the traditional river network routing algorithm, with deficiency in reproducing high-resolution flood propagation and floodplain storage at large scale. This hampers the effectiveness of LSMs in climate change impact assessment. To this end, the proposed study aims to improve the LSM’s native routing scheme by integrating the macro-scale hydrological model and hydrodynamic river routing model. Using this couple model, this study attempts to illustrate the critical role of routing scheme in hydrological extremes simulation. Furthermore, this hydrologic-hydrodynamic model is coupled with multiple general circulation models (GCMs) archived in the state-of-the-art Coupled Model Intercomparison Project Phase 6 (CMIP6) climate change experiments to project future changes in hydrological extremes and their associated risk in the drought/flood-prone Lancang-Mekong River Basin (LMR). The results can provide great implications for assessing water-related risk under a changing climate, and also benefits the climate change coping strategies in the LMR region.