Temperature differences between the atmosphere and river water allow rivers to be used as a hydrothermal energy source. River-water heat pump systems are a relatively non-invasive renewable energy source; however, effluent discharged from the heat pump can cause downstream temperature changes which may impact sensitive fluvial ecosystems. The temperature change associated with heat pump discharge in a river reach was examined using the heat transfer equation in a previous study, but not using models. There were also no studies on the impact of temperature change due to heat pump discharge on river ecosystem elements such as endangered fishes. Therefore, in this study, the water temperature recovery distance of effluent was estimated for a river section in the Han River Basin, Korea, using the heat transfer equation and the Environmental Fluid Dynamic Code (EFDC) model. The water temperature recovery distance was estimated to be 9.7 km using the heat transfer equation and 5 km using the EFDC model in summer. It was also estimated to be 4.5 km using the heat transfer equation and 6.7 km using the EFDC model in winter. Results showed that the water temperature recovery distance results estimated by the heat transfer equation had greater variation than the EFDC model. The water temperature recovery distance could also be used as an objective indicator to decide the reuse of downstream river water. Furthermore, as the river system was found to support an endangered fish species that is sensitive to water environment changes, care should be taken to exclude the habitats of protected species affected by water temperatures within water temperature recovery distance.

中文翻译：

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温度恢复距离的估算及热泵排放对河流生态系统的影响

大气和河水之间的温差使河流可以用作热液能源。河水热泵系统是一种相对非侵入性的可再生能源；然而，从热泵排出的污水会导致下游温度变化，这可能会影响敏感的河流生态系统。在先前的研究中使用传热方程检查了与河段热泵排放相关的温度变化，但未使用模型。也没有研究热泵排放引起的温度变化对濒危鱼类等河流生态系统要素的影响。因此，本研究对韩国汉江流域某河段的出水水温恢复距离进行了估算，使用传热方程和环境流体动力学代码 (EFDC) 模型。夏季使用传热方程估算水温恢复距离为 9.7 公里，使用 EFDC 模型估算为 5 公里。在冬季，使用传热方程估计为 4.5 公里，使用 EFDC 模型估计为 6.7 公里。结果表明，由传热方程估计的水温恢复距离结果比EFDC模型有更大的变化。水温恢复距离也可作为决定下游河水回用的客观指标。此外，由于发现河流系统支持一种对水环境变化敏感的濒危鱼类，