Streams are complex where biology, hydrology, and atmospheric processes are all important. Because quantifying and modeling of these systems can be challenging, many teams go directly to prescribed restoration treatments and principles. Restoration on the Middle Fork of the John Day River in Oregon, USA, shows how a project that was designed according to widely accepted restoration principles may lead to outcomes contrary to one of the project's stated goals: reducing peak temperatures for endangered salmonids on the site. This study employed the most sophisticated equipment available for stream temperature monitoring, including approximately 1 million independent hourly measurements in the 2-week period considered. These data were collected along the river channel with fiber optic–distributed temperature sensing and were used to quantify thermal dynamics. These observations were paired with a physically based stream temperature model which was then employed to predict temperature change from design alternatives. Restored-reach impact on peak temperature was directly correlated with the air–water interfacial area and the percentage of effective shade (R² > 0.99). The increase in air–water area of the proposed design was predicted to increase daytime stream temperature by as much as 0.5°C upon completion of the work. Shade from riparian vegetation was found to potentially mitigate stream temperature increases, though only after decades of growth. A moderately dense canopy of 5 m tall trees blocking 17% of daily shortwave solar radiation is predicted to mitigate predicted temperature increases over the 1,800 m reach but also increases nighttime temperatures due to blocking of long-wave radiation. These outcomes may not be intuitive to restoration practitioners and show how quantitative analysis can benefit the design of a project. This is significant in an area where riparian vegetation has been difficult to reestablish. Without quantitative analysis, restoration efforts can lead to outcomes opposite to stated goals and may be costly and disruptive interventions to fragile stream systems.

中文翻译：

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流重建替代方案的高分辨率温度建模

河流是复杂的，其中生物学、水文学和大气过程都很重要。由于对这些系统进行量化和建模可能具有挑战性，因此许多团队直接采用规定的修复处理方法和原则。美国俄勒冈州约翰戴河中叉的修复展示了根据广泛接受的修复原则设计的项目如何导致与项目既定目标之一相反的结果：降低现场濒危鲑鱼的峰值温度. 这项研究采用了最先进的设备，可用于河流温度监测，包括在考虑的 2 周内每小时进行约 100 万次独立测量。这些数据是通过光纤分布式温度传感沿河道收集的，并用于量化热动力学。这些观察结果与基于物理的流温度模型配对，然后用于预测设计备选方案的温度变化。恢复范围对峰值温度的影响与气水界面面积和有效遮荫的百分比直接相关。[R ² > 0.99）。预计在工程完成后，拟议设计中空气-水域面积的增加将使白天的水流温度升高 0.5°C。河岸植被的遮荫被发现可以潜在地减轻溪流温度的升高，尽管只有经过几十年的增长。5 m 高的中等密度树冠阻挡了 17% 的每日短波太阳辐射，预计可以缓解 1,800 m 范围内预测的温度升高，但也会由于长波辐射的阻挡而增加夜间温度。这些结果对于修复从业者来说可能并不直观，并表明定量分析如何有利于项目设计。这在河岸植被难以重建的地区意义重大。没有定量分析，