全球变化背景下极端水文事件的模拟和评估研究

The hydrological cycle has been significantly affected by global change, including not only climate change but also the increasing human disturbance associated with socioeconomic development during the past several decades. So far, the impacts of socioeconomic development on extreme hydrological events (EHEs), are not fully evaluated due to the insufficient representation of the impacts of socioeconomic development in hydrological models. .This project aims to quantify the impacts of climate change and socioeconomic development on EHEs and reveal the underlying mechanisms by developing an integrated large-scale hydrological model (IHM). The IHM will couple a socioeconomic development parameterization with the distributed biosphere-hydrological (DBH) model to address the impact of socioeconomic development. The inundation model CaMa-Flood will be coupled to enhance the simulation of flood and inundation. The IHM also includes improved crop irrigation module and reservoir regulation based on the DBH model. The IHM will be validated and used to simulate EHEs in four basins over the world, namely, the Yangtze River basin in China, the Mississippi River basin in the USA, the Danube River basin in Europe, and the Murray Darling basin in Australia. The spatiotemporal characteristics of the EHEs will be illustrated based on the IHM simulations in the four basins for the past decades, and the contributions of climate change and socioeconomic development to the change of EHEs will be separated. Future changes of EHEs will be projected by the IHM along with the climate outputs of general circulation models (GCMs) provide by the Coupled Model Intercomparison Project (CMIP) Phase 6. The impacts of future climate change and socioeconomic development will be evaluated, which could be used for reference for decision-making for both adaptation and mitigation associated with EHEs. This study will improve our understanding of the evolution of EHEs and provide a useful tool for the assessment of water-related hazards induced by EHEs in the context of global change.

过去几十年全球环境变化给水循环带来了巨大的影响，随着社会经济的发展，人类活动对水文过程的干扰程度持续增强。目前，大尺度陆面水文模型对社会经济发展的考虑还不够完善，难以评估社会经济发展对极端水文事件变化的影响。本项目拟在分布式生物圈水文模型（DBH）基础上发展大尺度极端水文事件模拟技术。耦合全球水动力学模型CaMa-Flood以改进DBH模型对洪水演进和淹没过程的模拟，完善DBH模型的作物灌溉需水和水库调度模块，发展社会经济需水估算方法并与DBH模型耦合，以便模拟气候变化和社会经济发展对极端水文事件的影响。在全球四个典型大河流域进行极端水文事件模拟和验证，阐明典型流域过去几十年极端水文事件演变规律及其机理，定量评估未来气候变化和社会经济发展分别对典型流域极端水文事件变化的贡献。本项目可以为全球变化背景下水灾害风险的评估和应对提供科学依据和有效工具。

全球变化给水循环带来了深刻影响，全球变暖可能导致水循环加速从而引发更多极端水文事件。气候变化和人类活动的双重影响下，水文过程演变更为复杂，增加了水循环变化归因和极端水文事件模拟的困难。因此，亟需发展高效的水循环变化模拟工具，以便更好地开展变化环境下的极端水文事件模拟和预估。本项目通过改进作物生长和需水模拟、环境需水量估算模块，发展全球水文模型，开展了全球/全国尺度径流变化模拟，评估了水资源短缺及其影响。研究成果主要包括以下两个方面。（1）发展了作物生长和需水模拟模块，评价了不同环境流量估算方法对径流和水资源短缺模拟的影响，在大尺度水文模型中耦合了作物模块和环境流量估算模块。（2）发展了全球水文模型，在全球和全国尺度对模型开展了应用研究，评估了模型适用性。（3）定量区分了人类活动和气候变化对水循环变化的贡献，评估了全球变化背景下全球和我国水资源短缺压力的演变及其影响。结果显示，2021-2050年期间气候变化可能导致中国每年有40%以上人口面临严重缺水压力。因此，制定气候变化减缓和应对措施迫在眉睫。