## 5 Summary and Conclusions  
From a recent policy perspective, the hydropower reservoir is a major component of the integrated water management system, and its status and value need to be re-evaluated as renewable energy for the realization of zero carbon. However, despite the progress in related technologies, the past methodologies are being used for dam operation and evaluation. In consideration of enhancing the status of the hydropower reservoir and strengthening its role as a water resource manager contributing to the water resource system, it was urgent to establish a plan to secure the efficiency of dam operation in terms of watershed management, including water supply and flood control. Therefore, in this \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Dam**} & \multicolumn{2}{c}{**Power Generation (MWh)**} & \multirow{2}{*}{**Comparison**} & \multirow{2}{*}{**Resilience**} \\ \cline{2-2} \cline{4-5}  & **Historical Data** & & & \\ \hline Hwacheon & 217,591 & 204,942 & \(-\)12,649 & 0.350 \\ \hline Chuncheon & 130,571 & 120,451 & \(-\)10,120 & 0.300 \\ \hline Uiam & 146,786 & 174,531 & 27,745 & 0.729 \\ \hline Cheongpyeong & 269,880 & 416,556 & 146,676 & 0.858 \\ \hline Total System & 764,828 & 916,480 & 151,652 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of historical data and simulation results for power generation. Figure 10: Comparison of historical data and simulation results. (**a**) Water level; (**b**) Outflow discharge. study, the concept of resilience was applied to the operation of a hydropower reservoir, and a methodology to evaluate it was presented. The goal of this study is to propose the optimal operation rules for hydropower reservoirs that can maximize power sales and secure flood control and water usage performance from a resilience point of view. In this study, the concept of resilience suggested by [PERSON] et al. (2021) was introduced and defined in the power generation system of a hydropower reservoir. The concept was applied to four hydropower reservoirs connected in series to the Bukhangang watershed in Korea. The operation scenario was constructed with the target water level and target outflow discharge set as variables when the dam manager establishes the multiple operation plan in Korea. Based on the historical data on dam water level and outflow discharge, a scenario was constructed by increasing or decreasing them at a certain rate. The optimal scenario was derived by setting the electricity sales as a target function. For the simulation, HEC-5 developed by the U.S. Army Corps of Engineers was used, and the simulation results were used to evaluate the power generation performance, flood control performance, and water usage performance. Power generation performance is evaluated by electricity sales. The flood control performance is calculated by the number of days at risk of flooding and spillway discharge, and the water usage performance is calculated by the number of days at risk of drought and the amount of water shortage. For the optimal operation rule, the power generation performance is prioritized, and the additional performance is limited to within the score calculated based on past performance data. The optimal rule curve considering resilience was presented using the observation inflow data from 2006 to 2013. When operating hydropower reservoirs in connection, it was confirmed that they must be operated with high resilience to maximize power production. Comparing the simulation results with the past performance during 2006-2013, power generation increased by about 19.83% when operated with high resilience. However, since the current scenario consists of increasing or decreasing only at a certain rate, it cannot be considered that all possible scenarios are reflected. Therefore, if these limitations are overcome in the future, it will be possible to derive an operation rule that can secure additional performances while maximizing the electricity sales of the hydropower reservoir.