Water-energy nexus refers to the interdependence between water resources and energy conversion, and it encompasses the multiple phases of electric power generation and water processing and distribution. Current policies for the utilization of freshwater resources in electric power generation regulate the thermal discharges and their effect on the aquatic life. Water withdrawals and consumption polices are mainly prescribed at the regional level instead. This paper focuses on the effects of water policy constraints on electric power generation in changing climate conditions. A river basin is simulated, which hosts two hydraulically linked power generating stations, namely an upstream hydropower plant with reservoir and a downstream thermal power plant. Two alternative cooling designs are tested for the thermal power plant, i.e. once-through and wet tower cooling. Severe drought conditions leading to small river flows and high water temperatures are analyzed, and the limitations to the energy conversion at the thermal plant stemming from the water policies are quantified. The results show that some small flexibility in the water policy constraints during extreme droughts can secure a significant amount of energy to the power system, which would have been curtailed otherwise. Remarkably, the relaxation of 1.5 °C in the water policy constraints prevents the curtailment of 42% of the generation capacity of a 1000 MW_e thermal plant during the analyzed 24 h drought scenario. In general, the type and the required amount of constraint relaxation depend on the environmental conditions and are to be judged case-by-case. Furthermore, the smart scheduling of water resources grants a 7% increase of the energy converted during droughts in the hydraulically linked hydro and thermal power plants. Finally, the analysis shows that once-through cooling systems are extremely sensitive to changes in water flow and temperature opening space for less sensitive technologies, i.e. wet cooling towers.

水能关系是指水资源与能源转化之间的相互依存关系，它涵盖了发电，水处理和分配的多个阶段。当前在发电中利用淡水资源的政策规定了热排放及其对水生生物的影响。取水量和用水量政策主要是在区域一级制定的。本文关注气候变化条件下水政策约束对发电的影响。模拟了一个流域，该流域拥有两个水力发电站，即一个上游的水力发电厂和一个下游的火力发电厂。针对火力发电厂测试了两种替代冷却设计，即 一次通过和湿式塔冷却。分析了导致河流流量小和水温高的严重干旱条件，并量化了由于水政策而导致的热电厂能量转换的局限性。结果表明，极端干旱期间水政策约束中的一些小灵活性可以确保向电力系统提供大量能源，否则将减少这些能源。值得注意的是，在水政策约束中放宽1.5°C可以防止削减1000兆瓦发电量的42％结果表明，极端干旱期间水政策约束中的一些小灵活性可以确保向电力系统提供大量能源，否则可以减少这些能源。值得注意的是，在水政策约束中放宽1.5°C可以防止削减1000兆瓦发电容量的42％结果表明，极端干旱期间水政策约束中的一些小灵活性可以确保向电力系统提供大量能源，否则可以减少这些能源。值得注意的是，在水政策约束中放宽1.5°C可以防止削减1000兆瓦发电容量的42％_Ë在热电厂分析24小时的干旱情况。通常，约束放松的类型和要求的量取决于环境条件，并应根据具体情况进行判断。此外，水资源的智能调度使水力发电站和火力发电厂的干旱期间转换的能量增加了7％。最后，分析表明，对于不太敏感的技术（例如湿式冷却塔），直通式冷却系统对水流和温度开放空间的变化极为敏感。