基于多源观测资料的长江源区水文过程气候变化响应研究

The Yangtze River Source Region (YSR) is one of the most important regions of National Ecological Security Shelter Zone on the Tibetan Plateau (TP). However, YSR lies as the transition region of the inner TP eco-geographical regions, so it is sensitive to climate change due to its distinct spatial heterogeneities in land surface processes. As such heterogeneities can not be efficiently fetched by single or limited observation means, this study is to make full uses of multi-observed and reanalyzed data to describe the spatial and temporal variations of land surface parameters, so as to help explaining the hydrological response of the YSR to climate change. Firstly, the multi-observed and reanalyzed data will be scale-integrated to construct the water balance of 5-km grids, which will be examined at the scales of Dangqu watershed, Tuotuohe watershed and the whole YSR watershed by hydrological gauge records. Then, the land surface elements controlling the YSR hydrological process will be examined, and the temporal trend of discharge and related parameters will be explored to reveal the associations of land surface conditions with climate change. Finally, the sensitivities of water balance components to climate change in terms of air temperature, solar radiance and precipitation will be further examined. In such way, the hydrological response mechanism of the YSR to climate change and its spatial heterogeneity in the YSR is promising to be revealed.

长江源区是我国青藏高原生态安全屏障极为重要的组成部分，其生态水文意义显著；地处高原腹地的生态地理过渡带，又是青藏高原对气候变化的敏感区之一。但该区域地表系统空间异质性强，单一或有限的观测手段不能有效揭示其水文过程的空间分异，因此本项目将以水文过程的空间分异为立足点，利用优势互补的多源观测及同化模拟再分析资料，研究长江源区水文过程的气候响应机制,该工作将对长江源区的生态保护有实际参考价值。..基于该研究思路，本项目将：首先，尺度融合并校正多源观测及模拟资料；然后，构建长江源区时空连续的5km栅格地表水量平衡，并在布曲/沱沱河/整个源区3个尺度进行验证；进而，检验长江源区水文过程变化的控制要素，分析相关地表因子及径流的变化趋势；最后，通过分析长江源区蒸散发/地表冻融/流域径流等对气候变化(气温/辐射/降水)的敏感性及空间分异，解析长江源区水文过程对气候变化的响应机制。

长江源区是我国青藏高原生态安全屏障极为重要的组成部分，其生态水文意义显著；地处高原腹地的生态地理过渡带，又是青藏高原对气候变化的敏感区之一。但该区域地表系统空间异质性强，单一或有限的观测手段不能有效揭示其水文过程的空间分异，因此本项目利用优势互补的多源观测及同化模拟再分析资料，研究了长江源区水文过程的气候响应机制,该工作将对长江源区的生态保护有实际参考价值。..基于该研究思路，本项目：a）分析了研究区地表因子空间异质性，结合地形地貌、地表覆被、气温地温、卫星降水等最基本的地表相关要素，分析了长江源区的地表水文空间分异特征；b）进行了多源数据验证与尺度融合，重点对同化及卫星降水产品，在流域尺度上进行了验证和降尺度处理；c）研究了青藏高原近地表土层升温对径流过程的影响，基于45个气象站点的多层土壤观测数据，探讨了受气候变暖影响的冻土可能变化；d）探讨了水文过程的气候响应机制：分析了长江源区降水/蒸散发/地表冻融的季相规律和年际趋势，基于CRHM水文模型、GIPL冻土模型和VIC陆面模型，构建了5 km栅格的长江源区月/年尺度水量平衡，揭示了研究区过去45年蒸散发/地表冻融/径流对气候变化的敏感性及区域差异，指出了长江源区水文气候变化响应规律。