Hydrological response of catchments to declining snow and ice storage

正在发生的和预计的气候变化将逐步减少山区和其他寒冷气候集水区的季节性（雪）和半永久性（冰川、永久冻土）储水量。这些冰冻圈的变化可能会极大地改变这些集水区的新冰期河流状况，重新定义新的风险水平（干旱、洪水）以及淡水衍生的生态系统服务（例如农业、文化灌溉、水力发电）。这项为期5年的研究计划旨在利用观测与模拟相结合的方法，研究气候变率对冰冻圈的影响以及相关融水对流域水文的贡献。该计划将追求三个目标：(1)估计气候变化对冰川化山区集水区融水通量的影响；(2)验证积雪模式模拟积雪时空动态的能力；(3)评估简单水文模型在未来气候条件下预测复杂水文系统的能力。为此目的，将研究两个具有不同地形、气候和冰冻圈储水量的实验集水区：智利的拉佩尔河（地中海气候，部分冰川化）和加拿大的马塔温河（积雪为主，大陆湿润气候）。我们提出的方法学方法将(1)使用冰川水文模型作为学习工具，以更好地约束流域的主导过程；(2)量化这些过程的气候敏感性，以便对潜在的未来变化提供物理理解。敏感性分析的结果可以很容易地传达给水资源管理者，并应用于不断改进的气候预测。在Matawin流域部署分布式积雪观测系统（SNOS），研究积雪和融水产流的时空变化规律，为模型试验提供观测依据。简单的水文模型能够推断出当前气候条件之外的情况吗？通过挑战常见的概念水文模型来重现具有不同边界条件（气候、地形）的“虚拟集水区”生成的合成河流流量数据，将解决水文学中这个持续存在的问题。一个空间分布的、基于物理的水文模型将被用作虚拟集水区平台。我们期望该研究项目产生的结果能够为寻求适应性策略的水资源管理者带来实用的有价值的信息，并为冰雪水文学领域的理论进步（模型模拟当前和未来冰雪水文学的能力）带来理论进步。

The ongoing and projected climate change will progressively reduce the seasonal (snow) and semi-permanent (glaciers, permafrost) storage of frozen water in mountain and other cold climate catchments. These cryospheric changes could drastically modify the nivo-glacial river regime of these catchments, redefining new risk levels (drought, floods) as well as freshwater-derived ecosystems services (e.g. agriculture culture irrigation, hydroelectricity production). This 5-year research program aims to study the impact of climate variability on the cryosphere and related meltwater contribution to catchment hydrology using a combined observational-modelling approach. The program will pursue three objectives: (1) to estimate climate change impacts on meltwater fluxes from glacierized mountain catchments; (2) to test the ability of snow models to simulate spatio-temporal snow dynamic; (3) to assess the ability of simple hydrological models to predict complex hydrological systems in future climates. Two experimental catchments with different topography, climate and cryospheric storage will be studied for this purpose: the Rapel River in Chile (Mediterranean climate, partly glacierized) and the Matawin River in Canada (snow dominated, continental-humid climate). Our proposed methodological approach will (1) use glacio-hydrological models as a learning tool to better constrain the dominant processes in the catchment, and (2) quantify the climate sensitivity of these processes in order to provide a physical understanding of potential future changes. Results from sensitivity analyses can be easily communicated to water managers and applied to the continuously refining climate projections. A distributed SNow Observing System (SNOS) will be deployed in one catchment (Matawin) to study the spatio-temporal variability of snow accumulation and meltwater runoff generation, and to provide an observational basis for model testing. Are simple hydrological models able to extrapolate beyond the present climate conditions? This ongoing problem in hydrology will be addressed by challenging common conceptual hydrological models to reproduce synthetic river discharge data generated by a 'virtual catchment' with different boundary conditions (climate, topography). A spatially-distributed, physically-based hydrological model will be used as a virtual catchment platform. We expect the results generated by this research program to bring both practical valuable information for water managers seeking adaptive strategies as well as theoretical advances in the field of snow and ice hydrology (ability of models to simulate present and future snow and ice hydrology).