Seasonal thermal stratification in reservoirs changes the thermal regime of regulated river systems as well as stream temperature responses to climate change. Cold releases from the reservoir hypolimnion can depress downstream river temperature during warm seasons. Recent large‐scale climate change studies on stream temperature have largely ignored reservoir thermal stratification. In this study, we used established models to develop a framework which considers water demand and reservoir regulation with thermal stratification and applied this model framework to the southeastern United States. About half of all 271 reservoirs in our study area retain strong thermal stratification by the 2080s (2070–2099) under RCP8.5 even as median residence times decrease to 60 days from 69 days in the historic period (1979–2010). Reservoir impacts on downstream temperatures become slightly weaker in the future because of higher air temperature and stronger solar radiation. We defined a “cooling potential” to quantify the thermal energy that a water body can absorb before exceeding a water temperature threshold. In the future, higher river temperatures will reduce the cooling potential for all river segments, but more so for river segments minimally impacted by thermal stratification. Reservoir impacts on cooling potential remain strong for river segments downstream of reservoirs with strong thermal stratification. We conducted a sensitivity analysis to evaluate the robustness of our findings to errors in the hydrological simulations. Although river segments subject to reservoir regulation are more sensitive to errors in hydrology than those without regulation impacts, our overall findings do not materially change due to these errors.

中文翻译：

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水库改变河流热状况对气候变化的敏感性：以美国东南部为例

水库的季节性热分层改变了调节河系的热态以及河流温度对气候变化的响应。在温暖的季节，来自水库低渗的冷释放会降低下游河流的温度。最近关于河流温度的大规模气候变化研究在很大程度上忽略了储层的热分层。在这项研究中，我们使用已建立的模型来开发考虑热分层的考虑水需求和水库调节的框架，并将该模型框架应用于美国东南部。在RCP8.5下，到2080年代（2070-2099），我们研究区域中所有271个储层中约有一半仍保持强烈的热分层，即使中位停留时间从历史时期（1979-2010）的69天减少到60天也是如此。由于更高的气温和更强的太阳辐射，未来储层对下游温度的影响将变得稍弱。我们定义了一个“冷却潜能”，以量化水体在超过水温阈值之前可以吸收的热能。将来，较高的河流温度将降低所有河流段的冷却潜力，但对于受热分层影响最小的河流段则更是如此。对于具有强烈热分层作用的水库下游河段，水库对冷却潜力的影响仍然很大。我们进行了敏感性分析，以评估我们的发现对水文模拟错误的鲁棒性。尽管受水库监管的河段比没有监管影响的河段对水文误差更敏感，