纳木错流域冰川物质平衡变化对径流热量的影响研究

Water temperature serves as a fundamental physical property of aquatic environments. Within cryosphere, glacier-fed streams exhibit distinctive thermal regimes due to the influence of snow and glacier melt, and they are inhabited by a specialized cool water community. The role of water temperature as a driver of ecosystem processes is particularly significant in glacierized headwater river basins because of the strong coupling and high sensitivity between atmospheric and in-stream processes. The Nam Co basin is selected as a typical study area with highly glacier covered and unique with long term observations of glacier mass balance, hydrology, meteorology and stream temperature. The objective of the project is to detect the thermal regime and heat flux between the glacier-fed river and unglacier-fed river, using the data from hydrometric stations and meteorological station, explicit the hydrological and climatologic processes controlling the river thermal regime, and evaluate the glacier mass balance response to the thermal regime and heat flux. This is important for predicting changes in water cycle and the ecological environment in the future.

河水温度是水生环境中物理化学性质基础。在冰冻圈地区，受积雪和冰川融水的影响，径流表现出独特的热状况，形成特有的冷水生态系统。由于大气和河流内部过程之间强烈的耦合和高敏感度，河流热量机制作为生态系统的重要驱动因素在冰川流域表现的尤为显著。青藏高原大部分冰川呈加速退缩趋势，迫切需要开展冰川退缩对河水热通量影响研究。本项目拟选择青藏高原纳木错流域，依托已有的野外工作基础，获取冰川变化、水文、气象、河水热量等数据，运用数值模拟计算方法定量解析河水热量机制的时空变化，揭示冰川补给径流和非冰川补给径流的热通量特征，明确冰川流域中控制径流热量机制的主要过程，评估冰川物质平衡变化对河水径流热量机制的影响，探讨青藏高原内陆湖流域在未来气候变化下的热量平衡。

河水温度是影响水生环境中物理、化学及生物过程的关键参数之一。河在冰冻圈地区，受到积雪和冰川融水的影响，径流表现出独特的热状况，形成特有的冷水生态系统，河水温度作为生态系统的重要驱动因素在冰川流域表现得尤为显著。本项目在青藏高原纳木错流域，依托已有的野外工作基础，获取冰川变化、水文、气象、河水热量等数据，运用数值模拟计算方法定量解析河水热量机制的时空变化。研究结果表明，河水温度在2008年与2007/2009年大致相似。对冰川河流而言，夏季河水温度均值较以及日变化幅度较小，河水平均温度(4.0 - 6.5°C)最低，并从冰川末端开始沿河流向下游增加(+0.13 - +0.28°C km–1)。对非冰川河流而言，河水温度平均约为9.0 °C，且较高温度出现在不同年份的夏季。这种差异说明河水温度主要受径流以及降水的显著影响，特别是当冰川融水对冰川径流的贡献大于50%时，冰川融水将直接影响河水温度。该研究揭示了高海拔地区冰川补给径流和非冰川补给径流的热通量特征。