Abstract Conservation planners and resource managers seek information about how the availability and locations of cold-water habitats will change in the future and how these predictions vary among models. We used a physical process-based model to demonstrate the implications of climate change for streamflow and water temperature in two watersheds with distinctive flow regimes: the Snoqualmie watershed (WA) and Siletz watershed (OR), USA. Our model incorporated a downscaled ensemble of global climate model outputs and was calibrated with in situ and remotely sensed water temperatures. We compared predictions from our processed-based model to those from a publicly available and widely used statistical model. The process-based model projected greater changes in summer maximum water temperatures for the mixed-rain-snow Snoqualmie watershed than for the rain-dominated Siletz watershed as a result of the near-complete loss of winter snowpack and significant reduction in summer flow in the Snoqualmie watershed expected by the 2080s. Both models projected generally similar future spatial patterns of maximum water temperature in the two rivers, with cool reaches distributed farther upstream and fewer in number. However, the process-based model projected higher spatial heterogeneity in water temperature due to our spatially explicit simulation of streamflow and because we calibrated the model with spatially continuous remotely sensed water temperature data. We used stream temperature projections to assess the vulnerability of Pacific salmon and trout to changes in the spatial distribution of cold-water habitats during August by the 2080 s. Results suggest that salmonids may have fewer summertime cold-water habitats in both watersheds. Projected stream warming may further limit particular species and life stages, especially in the Snoqualmie watershed. Our comparison of models highlights the importance of considering what might be gained by using a process-based model for evaluating and prioritizing management actions that mitigate climate impacts on cold-water habitats for stream fishes.

中文翻译：

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预测气候变化对河流温度的时空显性影响：对冷水鱼类的模型比较和影响

摘要 保护规划者和资源管理者寻求有关冷水栖息地的可用性和位置在未来将如何变化以及这些预测如何因模型而异的信息。我们使用基于物理过程的模型来展示气候变化对两个具有不同流态的流域的水流和水温的影响：Snoqualmie 流域 (WA) 和 Siletz 流域 (OR)，美国。我们的模型结合了全球气候模型输出的缩小集合，并使用原位和遥感水温进行了校准。我们将基于处理的模型的预测与来自公开可用且广泛使用的统计模型的预测进行了比较。基于过程的模型预测，由于冬季积雪几乎完全消失和夏季流量显着减少，雨雪混合型 Snoqualmie 流域夏季最高水温的变化大于以雨为主的 Siletz 流域。预计 2080 年代将出现斯诺夸尔米分水岭。两种模型都预测了两条河流未来最高水温的空间格局大体相似，凉爽的河段分布在更远的上游，数量更少。然而，由于我们对水流进行了空间显式模拟，并且我们使用空间连续的遥感水温数据校准了模型，因此基于过程的模型预测了水温的更高空间异质性。我们使用溪流温度预测来评估太平洋鲑鱼和鳟鱼对 2080 年代 8 月期间冷水栖息地空间分布变化的脆弱性。结果表明，鲑鱼在两个流域的夏季冷水栖息地可能较少。预计的河流变暖可能会进一步限制特定物种和生命阶段，尤其是在 Snoqualmie 流域。我们对模型的比较强调了考虑通过使用基于过程的模型来评估和优先考虑减轻气候对溪流鱼类冷水栖息地的影响的管理行动可能会获得什么的重要性。预计的河流变暖可能会进一步限制特定物种和生命阶段，尤其是在 Snoqualmie 流域。我们对模型的比较强调了考虑通过使用基于过程的模型来评估和优先考虑减轻气候对溪流鱼类冷水栖息地的影响的管理行动可能会获得什么的重要性。预计的河流变暖可能会进一步限制特定物种和生命阶段，尤其是在 Snoqualmie 流域。我们对模型的比较强调了考虑通过使用基于过程的模型来评估和优先考虑减轻气候对溪流鱼类冷水栖息地的影响的管理行动可能会获得什么的重要性。