基于稳定同位素的塔里木河流域西南部降水水汽来源组成特征研究

Tarim River Basin is the largest arid inland basin of China and is more sensitive to the global climate change. As the basic water resources of Tarim River Basin (TRB), atmospheric precipitation directly controls the amount, distribution pattern of water resources. The water vapor source is the material basis of precipitation, which affects the distribution and change of precipitation. Recent year, climate change has caused that the acceleration of water cycle and the increase of water vapor from outside of TRB. Besides, the climate warming and human activity resulted in the increase of evaporation vapor. The water vapor source of TRB became more complexity especially in the Southwest TRB. At present, the knowing of the characteristics of water vapor sources of precipitation of the Southwest TRB is lack and more attention has been paid for the influence of climate change on the contribution of different water vapor for precipitation. Based on the observing data of precipitation stable isotope, this project intends to analysis the spatial-temporal distribution of precipitation stable isotopes and evaluate the contribution of different water vapor on precipitation using the multiple isotopic component separation model and reveal the spatial- temporal variation of the characteristics of water vapor source and its influence mechanism in the Southwest TRB. The results will improve the understanding of the regional water cycle, and will be beneficial to the water resource management.

塔里木河流域是中国最大的干旱内陆流域，是全球气候变化的敏感区和强烈影响区，流域水资源匮乏，水问题严重。大气降水作为水资源的根本补给源，直接决定着流域的水资源总量及分布格局，而水汽来源作为降水的物质基础，影响着降水分布和变化。近年来，气候变化导致流域水分循环加剧，外部进入流域水汽增加；气温上升及人类活动亦导致内部蒸发水汽增加，流域水汽组成及来源日益复杂化，其中以流域西南部最为突出且存在水汽来源争议。目前国内对该区域水汽来源组成缺乏较全面的定量化研究。本项目拟选用环境同位素技术，通过野外降水同位素样品的收集和测定，分析塔里木河流域西南部降水同位素时空变化规律，判读影响研究区降水的主要水汽来源及其同位素特征，借助同位素多元混合模型，重点评估研究区不同水汽来源对于区域降水的贡献率，揭示流域降水水汽来源组成特征的时空变化规律及其影响机制。研究结果有助于深入认识区域水循环过程。

塔里木河流域是中国最大的干旱内陆流域，是全球气候变化的敏感区和强烈影响区，流域水资源匮乏，水问题严重。大气降水作为水资源的根本补给源，直接决定着流域的水资源总量及分布格局。近年来，气候变化导致流域水分循环加剧，外部进入流域水汽增加；气温上升及人类活动亦导致内部蒸发水汽增加，流域水汽组成及来源日益复杂化，其中以流域西南部最为突出且存在水汽来源争议。目前国内对该区域水汽来源组成缺乏较全面的定量化研究。本项目选用环境同位素技术，通过长期的野外降水同位素样品的收集和测定，表明研究区大气降水氢氧稳定同位素季节变化明显，呈现夏半年高、冬半年低的特点。高空一直受到西风的强烈影响，但其水汽通量值偏低；近地表风向受到多种因素影响，因而波动较大，其水汽通量值变化较大。冬季，塔里木河流域西南部地区受西风影响的范围及水汽通量均较大，西风强度为全年最大。高山地区的降水有23.17%来自于局地蒸发蒸腾形成的内循环水汽，而这一贡献率在江卡站仅为15.44%。研究结果有助于深入认识区域水循环过程。