青藏高原西部典型内流河和外流河河水氢氧稳定同位素分析和模拟对比研究

Dominated by both the Westerlies and the Indian monsoon, Ngari Prefecture on the western Tibetan Plateau (TP) is the boundary zone of interior drainage area and outflow region. During recent decades, changes of river runoff have received considerable scientific attention due to its relevance to water resources and local water cycles under the background of climate change. In this project, we present a study of isotope hydrological model conducted within Magazangbu catchment, a typical inland river basin of Pangong Lake at Ngari Prefecture, and the adjacent Shiquanhe catchment (the upper stream of the Indus River), a typical outflow river catchment on the western TP. This study aimed to: (1) Build a monitoring network of water stable isotopes, analyze the spatial-temporal variability of river water isotopes and identify their possible mechanisms. (2) Merge the water stable isotopes into the distributed hydrological model WEB-DHM, and build an isotope hydrological model WEB-DHM_iso. (3) Based on the sensitivity of water stable isotopic fractionation to climate variables, then comparatively analyze and model river runoff and dual water isotopes in river water for Magazangbu and Shiquanhe catchments, and further reveal the controls of land surface water cycles on river runoff. This project will improve our understanding of the processes and mechanisms behind catchment-scale hydrology and aid isotopic hydrological studies for other regions of the western TP.

青藏高原西部阿里地区位于印度季风与西风带的交错带，也是外流区与内流区的边界。近几十年，气候变化导致的该地区径流变化对当地水资源与水循环产生了深刻影响，是当前国际学术界关注的热点。本项目计划在青藏高原西部典型内流区—班公湖盆地内的麻嘎藏布流域和其毗邻外流区—狮泉河流域（印度河上游）开展稳定同位素水文模型耦合研究。（1）通过在流域尺度建立水体稳定同位素监测网络，揭示研究区河水稳定同位素时空变化特征及其主要影响因子。（2）将水体稳定同位素与分布式水文模型WEB-DHM耦合，创建WEB-DHM_iso模型。（3）基于水体同位素分馏对气候因子的敏感性，通过对比分析和模拟研究区内流河和外流河径流及河水稳定同位素变化，揭示地表水循环过程对径流形成的影响。本项目预期研究成果有利于深入理解该地区的水资源形成过程，以及气候条件在水循环过程中的作用；该方法可为其它流域稳定同位素水文过程研究提供借鉴。

青藏高原西部阿里地区位于西风带和印度季风作用的交错带；近几十年来，气候变化导致的该区径流变化对当地水资源与水循环产生了深刻影响，是当前国际学术界关注的热点。本项目选取青藏高原西部典型内流区—班公湖盆地内的麻嘎藏布流域和其毗邻外流区—狮泉河流域（印度河上游）开展稳定同位素与流域水文过程研究。取得如下研究成果和进展：. (1) 基于HYSPLIT水汽追踪模型，综合局地气象要素及大尺度天气系统，判定了伴随着水汽传输过程中的对流运动强度或温度格局是阿里地区降水稳定同位素的主要影响因子；. (2) 基于不同水体稳定同位素（降水、河水、地下水），定量计算了季风期降水对麻嘎藏布河水的贡献率约60%；综合模型蒸散发资料及卫星产品，对流域总蒸散发进行分割，定量计算了各分量的比例；. (3) 以阿里自动气象站资料校正ITP-Forcing，并驱动WEB-DHM，模拟了研究区径流；降水产品的不确定性及上游水库对径流模拟结果产生一定影响。. 项目成果有利于深入理解该地区的水资源形成过程，以及气候条件在水循环过程中的作用；研究方法可为其他流域稳定同位素水文过程研究提供借鉴。