How much selection and calibration of hydrological models influence climate change impact and adaptation conclusions?

科学界有一个很大的共识，那就是人们必须已经设想适应气候变化。在水文学中，气候变化影响的评估需要三个要素的结合使用。首先，气候预估是由全球环流模式（GCMs）与海洋和海冰模式相结合，在覆盖全球的范围内产生的长时间模拟。然后采用降尺度技术来协调大尺度气候模型与流域尺度（水管理最重要的尺度）之间的尺度不匹配。最后，一个水文模型模拟了未来的流域流出。如果大量的努力已经针对减少这种系统的前两个组成部分的不确定性，那么关于水文模型复杂性的作用的定量知识还很少。因此，本研究旨在通过寻求以下问题的答案来填补这一空白：水文模型的选择和校准对气候变化影响和适应结论的影响程度有多大？特别是，该项目将在四个水系上实施22个水文模型，以评估选择潜在蒸散发公式的影响以及确定相关水文模型参数的重要性。不适当的参数选择可能导致模型不像它试图模拟的自然系统那样运行，而气候变化可能会使潜在的蒸散发公式超出其校准范围。在拟议的研究中将使用四种未来气候预测，其目标是涵盖范围广泛的可能的未来温度和降水。评价和比较过程将不仅基于典型的水文评分和水平衡分量，还将利用实际大坝管理应用作为补充评价手段。此外，模拟中的巨大差异将通过详细观察模型结构来分析。所有这些工作的目的是提高加拿大及时调整其水管理计划的能力。

There is a large consensus in the scientific community that one must already envisage adaptation to climate change. In hydrology, the assessment of the impacts of changing climate demands the combined usage of three elements. First, climate projections are generated for long simulation time periods by global circulation models (GCMs), coupled to ocean and sea ice models, on a domain that covers the globe. Then a downscaling technique reconciles the scale mismatch between the large-scale climatic models and the watershed scale the most important scale for water management. Finally, a hydrological model simulates future watershed outflows. If lots of efforts have already targeted reducing the uncertainty of the first two components of such systems, little quantitative knowledge is as yet available about the role of hydrological model complexity. This study thus aims filling part of that gap by seeking an answer to the following: How much the selection and calibration of hydrological models influence climate change impact and adaptation conclusions? In particular, the project will implement twenty-two hydrological models on four river systems to evaluate the influence of the selection of a potential evapotranspiration formulation and the importance of pertinent hydrologic model parameter identification. Improper parameter selection may lead to a model that does not behave as the natural system it is seeking to simulate, while climate change may push potential evapotranspiration formulations beyond their calibration range. Four future climate projections will be used in the proposed study, the objective being to cover a wide range of plausible future temperatures and precipitations. The evaluation and comparison process will not only be based on typical hydrological scores and water balance components, it will also make use of real dam management applications as a complementary evaluation mean. Moreover, large differences in simulation will be analysed by looking in detail at the model structures. All this work aims improving Canada's ability for a timely adaptation of its water management schemes.