Reservoir operations and climate change can alter natural river flow regimes. To assess impacts of climate and hydropower operations on downstream flows and energy generation, an integrated hydropower operations and catchment hydrological model is needed. The widely used hydrological model Soil and Water Assessment Tool (SWAT) is ideal for catchment hydrology, but provides only limited reservoir operation functions. A hydropower reservoir operation routine (HydROR) was thus developed for SWAT to analyze complex reservoir systems under different policies. The Hydrologic Engineering Center’s Reservoir System Simulation (HEC-ResSim) model, a well-established reservoir simulation model, was used to indirectly evaluate functionality of the HydROR. A comparison between HydROR and HEC-ResSim under a range of operation rule curves resulted in R2 values exceeding 0.99. The HydROR was then applied to assess hydrological alterations due to combined impacts of climate change and reservoir operations of 38 hydropower dams in the 3S basin of the Mekong River. Hydropower production under climate change varied from −1.6% to 2.3%, depending on the general circulation model chosen. Changing the hydropower operation policy from maximizing energy production to maintaining ecological flows resulted in a production change of 13%. The calculation of hydrological alteration indices at the outlet of the 3S basin revealed that over 113% alteration in the natural river outflow regime occurred from the combined impacts of climate change and reservoir operations. Furthermore, seasonal flows and extreme water conditions changed by 154% and 104%, respectively. Alterations were also significant within the basin, and, as expected, were larger for high-head and small-river reservoirs. These alterations will adversely affect ecological dynamics, in particular, habitat availability. HydROR proved to be a valuable addition to SWAT for the analyses of complex reservoir systems under different policies and climate change scenarios.

中文翻译：

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SWAT 水电运行程序的开发及其在评估湄公河水文变化中的应用

水库运营和气候变化可以改变自然河流的流动状况。为了评估气候和水电运营对下游流量和能源生产的影响，需要一个综合的水电运营和流域水文模型。广泛使用的水文模型 Soil and Water Assessment Tool (SWAT) 是流域水文学的理想选择，但仅提供有限的水库运行功能。因此，为 SWAT 开发了水电水库操作程序 (HydROR)，以分析不同政策下的复杂水库系统。水文工程中心的水库系统模拟 (HEC-ResSim) 模型是一种完善的水库模拟模型，用于间接评估 HydroROR 的功能。在一系列操作规则曲线下，HydrROR 和 HEC-ResSim 之间的比较导致 R2 值超过 0.99。随后，HydroROR 被用于评估由于气候变化和湄公河 3S 流域 38 座水电大坝的水库运营的综合影响而导致的水文变化。气候变化下的水电生产从 -1.6% 到 2.3% 不等，具体取决于所选的环流模型。将水电运行政策从最大限度地提高能源生产改为维持生态流量，导致生产变化为 13%。对3S流域出口水文变化指数的计算表明，自然河流流出状况的变化超过113%是由气候变化和水库运行的综合影响造成的。此外，季节性流量和极端水条件分别变化了 154% 和 104%。盆地内的变化也很显着，正如预期的那样，高水头和小河流水库的变化更大。这些变化将对生态动态产生不利影响，尤其是栖息地的可用性。事实证明，HydroROR 是 SWAT 的宝贵补充，可用于分析不同政策和气候变化情景下的复杂储层系统。