基于能量—动力响应物理过程的冰川径流模拟研究

Knowledge of glacier change and the associated impact on water availability in western China has important scientific significance on instructing regional climate change under global warming, and has important realistic significance on managing regional water resource and ecological security, and on developing global change response measures. The proposed project will carry out field observations on glaciers of a catchment, including mass balance, surface velocity, ice thickness and temperature, glacier runoff and meteorology. These observations will further reveal the physical mechanisms of glacier mass balance and the changing process of consequent glacial morphology. Based on observed data combined with remote sensing-derived parameters, a glacier runoff model will be developed, which consists of two coupled components: a distributed surface energy-mass balance model that computes the energy available for melting from the exchange of energy between the debris-covered/debris-free surfaces and the atmosphere and treats processes occurring in the subsurface after meltwater percolates into the underlying layers, and an ice flow model that is based on the vertically integrated mass-conservation equation together with a simple flow law for the vertical mean ice velocity. The model can accurately simulate the changing processes of glacier energy-mass balance, dynamic response and glacier runoff. We first quantify the current contribution of glacier runoff to the total runoff and its corresponding role in the present-day hydrological regime of the catchment. Second, we investigate how changes in future glacier runoff and its contribution will affect the magnitude and timing of catchment river runoff under future climate scenarios.

认识气候变暖背景下冰川变化及其径流效应不仅对于认识区域气候变化具有重要的科学意义，而且对于西部地区合理利用冰川水资源维系社会经济发展、生态安全，制定气候变化应对措施具有重要的现实意义。拟申请项目将重点通过定位观测，结合遥感参数提取，系统揭示冰川物质平衡变化机理和其中的物理过程及由此引发的冰川形态（面积、长度、厚度、体积等）的变化过程，构建耦合分布式冰川能量-物质平衡模型和冰川动力过程的冰川径流模型，准确模拟冰川能量—物质平衡—动力响应—冰川径流变化过程；同时，基于不同情景气候模式数据集，耦合已有水文模型，揭示未来气候情景下冰川及其径流的变化趋势，分析气候变化、冰川响应影响下的冰川径流变化过程及其对流域水资源的影响。

随着全球气候变暖，研究冰川变化及其径流效应不仅对于认识区域气候变化具有重要的科学意义，而且对于青藏高原及周边地区合理利用冰川水资源以维系社会经济发展、生态安全，制定气候变化应对措施具有重要的现实意义。本项目以青藏高原东南部海螺沟冰川流域为试验区，开展了冰川消融、表碛厚度与热属性特征、冰川应变率、径流过程、气象等一系列野外观测与实验，结合多源遥感参数提取，应用构建的冰川能量—物质平衡模型，模拟了冰川区水的多相态转换过程，重建了过去几十年的冰川物质平衡变化序列；基于多源遥感影像和观测数据，系统分析了冰川运动速度、表面高程变化、底部滑动等冰川动力学参数的变化特征，以上述重建的冰川物质平衡变化序列驱动，开展了冰川动力学模型参数优化和模拟试验，改进了主流线冰川动力学模型；基于此，构建耦合冰川能量—物质平衡模型和冰川动力过程的冰川径流模型，结合已有水文模型，获取了流域径流及其各组成成分的变化过程，并综合分析了冰川径流对流域径流的影响及径流变化过程中的突变特征，同时分析了流域冰川区表碛空间分布对流域径流过程的显著影响。这些研究结果为进一步认识青藏高原东南部海洋型冰川变化及其对气候变化的动力响应过程、水资源效应奠定基础。