变化环境下三峡库区水循环及其伴生过程驱动机制研究

Ever since the Three Gorges Reservoir was put into operation, the reservoir area and its periphery suffer from frequent rain floods, droughts and other extreme weather events, heavily stretching the local water resources and water environment. The traditional hydrological model driven by precipitation input becomes insufficient to accommodate the emerging features of the reservoir area’s water cycle and its accompanying processes. This research adopts a new perspective of Land Water Cycle and flux exchange between energy and water of land surface process to illuminate the driving mechanism of water cycle in reservoir area and its associated Process in such large reservoirs as the Three Gorges. Based on the energy and water exchange flux monitoring of representative sites in the Three Gorges Reservoir area, specific remote sensing interpretation data are rectified, the flux change of moisture and energy on the influence of rainfall characteristics is analyzed and the reservoir driving mechanism of water cycle is established. In addition, based on the duality of water cycle key parameters under a changing environment, and nitrogen and phosphorus load transfer effect, the dynamic mechanism of nitrogen and phosphorus pollution load in the Three Gorges Reservoir area is suggested. In the final analysis, typical areas are selected to quantify the impact of climate change and human activities on dual mechanisms of water cycle and pollution load migration mechanisms. The research results are of theoretical significance to the research of energy and water exchange between land water cycle and land surface model; furthermore the research provides practical reference to water resources protection and sustainable utilization in large reservoir project area.

三峡水库建设运行以来，三峡库区及周边地区常发生暴雨洪涝和干旱等极端天气事件，使得库区的水资源与水环境面临着严峻的压力。传统以降水输入为驱动的水文模型已经难以适应库区水循环及其伴生过程的新特性。因此，以三峡库区作为研究对象，从陆地水循环与陆面过程间能量与水分交换通量变化的新视角来研究大型水库工程对库区水循环及其伴生过程的驱动机制。基于三峡库区代表性站点的能量与水分的交换通量监测，针对性校正遥感解译数据，剖析水分、能量的交换通量变化对降雨特性的影响，揭示库区水循环的驱动机制；基于变化环境下水循环关键参数二元特征及氮磷负荷迁移效应，揭示三峡库区氮磷污染负荷产生的动力机制。在此基础上，选择典型区定量评估气候变化和人类活动对二元水循环及污染负荷迁移动力机制的影响。研究成果不仅为陆地水循环与陆面模式间能量与水分交换研究具有理论指导意义，而且对于大型水库工程库区水资源保护和可持续利用等具有实际应用价值。

全球气候变化及大坝建设对区域水循环及其伴生过程的影响与调控一直是国际研究前沿关注的热点。尤其是变化环境对水循环的各个环节产生直接影响，使得水文极端事件发生概率增加，相应地库区水安全保障面临着更大的挑战。三峡工程作为全世界最大的水利枢纽工程，其兴建给库区经济发展带来了千载难逢的机遇，但同时库区的水资源、水生态和水环境也面临着严峻的压力。受气候变化和人类活动的综合影响，三峡库区的产水特性及其伴生过程在不同时间尺度上表现出新的演变特征，使得库区的水资源与水环境面临着严峻的压力。传统以降水输入为驱动的水文模型已经难以适应库区水循环及其伴生过程的新特性。为了科学评价大型库区流域水循环及伴生过程情势的发展态势，研究气候变化背景下大型库区流域水循环及伴生过程的演变规律，本项目围绕变化环境下三峡库区水循环及其伴生过程驱动机制这一主线，以三峡库区作为研究对象，从陆地水循环与陆面过程间能量与水分交换通量变化的新视角来研究大型水库工程对库区水循环及其伴生过程的驱动机制，重点开展了四方面研究内容：一是变化环境下降雨产汇流及负荷输移机制的实验研究；二是能量与水分交换通量对库区水循环的驱动作用研究；三是变化环境下三峡库区污染负荷迁移机制研究；四是三峡库区典型区水循环及其伴生过程驱动机制研究。通过上述研究，建立了三峡库区水循环演变规律及驱动机制理论，基于陆气耦合模拟与机理实验验证，阐释了库区流域坡面降雨-产流-氮磷流失复杂机理，研发了具有统一物理机制的陆面-水文耦合模型CLM-DWC，提出了地球系统模式下陆地水循环全过程模拟技术，阐明了库区“大气-陆面-水文”互馈作用机制，分析与预测了库区典型流域水循环及其伴生过程的变化规律。研究成果不仅对制定面向气候变化适应的水资源管理与生态环境保护战略具有重要现实指导意义，而且对于大型水库工程库区水资源保护和可持续利用等具有实际应用价值，应用前景广阔。