气候变化驱动下黄河源区下垫面变化及其径流效应

Hydrological effects of global warming and underlying surface change is currently an international scientific issue of significant importance in climate and ecological environmental sciences. Understanding the mechanisms of changes in runoff driven by both changes in climate and underlying coverage would be quite valuable for sustainable utilization of water resources of river basin and ecological environment protection, etc. Taking the source region of the Yellow River located in alpine-cold zone as a case, the proposed project focuses on climate change, underlying change and their hydrological effects. The specific objectives are as follows: (1) to analyze the changes in underlying coverage and the driven role of climate change; (2) to study for hydrological effects of different underlying types and their changes; (3) to reveal the driving and delivering mechanisms of climate change-underlying change-runoff response; (4) to establish grid-based distributed hydrological model for source region of the Yellow River which fully couples actions of changes in climate and its induced change in underlying surface; (5) to identify key drivers of runoff change and further assess their corresponding hydrological effects; (6) to exhibit grid-based spatial distribution map of changes in climate (e.g., precipitation, temperature), underlying surface (e.g., glacier, vegetation cover, frozen soil texture), and runoff on seasonal and annual scales. The proposed research will not only advance multi-disciplinary development of hydrology, climatology, and remote sensing science, but also provide direct scientific supports for ecological protection and water conservation in source region of the Yellow River. The expected outcomes of the research will include: to publish >10 academic papers (>5 SCI/EI journal papers) and an academic book, to apply for >3 national patents and software copyright.

全球变暖和下垫面变化的水文效应是目前国际上气候与生态环境领域的重大科学问题。认识二者驱动下的河川径流演变机制，对流域水资源可持续利用和生态环境保护规划等方面具有重要意义。以位于高寒区的黄河源区为研究对象，项目以气候-下垫面-径流响应为主线，系统分析气候驱动对下垫面变化的作用，研究径流对下垫面变化的响应机理，科学揭示气候-下垫面-径流驱动作用链的传递机制，构建耦合气候驱动及下垫面影响的黄河源区分布式水文模型，定量评估径流对多源驱动力耦合作用的响应，综合给出基于格点的气候驱动、下垫面变化和径流响应的空间图谱。研究成果不仅可直接支撑黄河源区生态保护和水源涵养，而且可极大促进气候、水文、遥感等多学科的交叉融合和发展。预期成果包括：发表学术论文10篇，其中SCI/EI期刊论文5篇，出版专著1本，申请专利和软件著作权3项。

黄河源区是受气候变化影响的敏感区，也是黄河流域重要的水源涵养区。研究气候变化驱动下黄河源区下垫面变化及其径流效应对于黄河流域生态保护和水资源可持续利用尤为重要。项目取得的主要成果如下：.（1）科学分析了黄河源区水文气象演变特征。黄河源区升温显著，年降水量受气候波动影响，呈现“增加-减少-增加”阶段性特征，年径流深和年降水量变化趋势一致，2000以来由于气候条件的暖湿，年径流量呈增加趋势。.（2）重点针对下垫面的植被覆盖、积雪、冻土等要素，解析了气候-下垫面的影响机制，黄河源区自2000年后人类活动导致的植被退化情势减缓，NDVI值呈增长趋势；流域面积平均年均雪深和积雪天数均呈不显著下降趋势，海拔高、气候寒冷的上游地区年均雪深对降水和气温变化更敏感，积雪期降水和气温对年均雪深变化的贡献率分别为43.7%和56.3%；黄河源区冻土始冻日延后、解冻日提前、冻结天数和最大冻深减少，速率分别为0.49d/a、-0.39d/a、-0.88d/a和-0.83cm/a，受地形影响，冻土多年平均冻结天数和最大冻深呈现从西北向东南减少的趋势；最大冻结深度与同期负积温呈显著的负相关关系，负积温的增加是黄河源区冻土最大冻结深度减少的主要原因。.（3）完善构建了黄河源区考虑积雪融雪和冻土冻融过程的GR4J_SM模型，该模型能够显著改善日径流过程模拟，特别是低流量过程；基于模型模拟评估了不同下垫面要素驱动的径流响应过程，以1980年和2000年为断点划分研究期为3个阶段，发现1980年之后气候变暖下流域降水的增加对径流增加具有正面贡献作用，但下垫面变化减少了多年平均径流。2000-2014年多年平均降水量虽高于1980-1999年，但气候波动和下垫面变化都导致径流下降。.基于项目研究成果，出版学术专著1部，发表学术论文19篇，其中SCI/EI源刊论文7篇，授权专利2项，登记软件著作权5项，培养研究生2名。