A Novel Generalized Semi‐Analytical Approach for Flood Control Reservoir Design

Abstract Flood control reservoir design requires estimating the total storable water volume or the maximum allowable discharge. This study proposes a novel Generalized Semi‐Analytical Approach (GS‐AA) to identify the maximum outlet discharge a flood control reservoir can handle for a specific return period. The approach exploits the analytical expression of Flow Duration Reduction (FDR) curves and combines them with an optimization algorithm to find the critical hydrograph and, thus, the hydrograph providing the maximum outlet discharge from the reservoir. The approach models the runoff process of the basin upstream of the reservoir, allowing users to choose any runoff model (RM). The proposed approach shows faster computational times than a fully numerical procedure, enabling potential users to explore and compare multiple reservoir configurations easily. Moreover, this approach addresses flow data limitation issues that prevent FDR curve derivation by correlating them to Intensity Duration Frequency curve parameters, expanding the potential applicability of the procedure in ungauged basins. Finally, results demonstrated the functionality of the procedure regardless of the chosen RM, offering widespread flexibility for users. The proposed GS‐AA is a robust and adaptable tool for design and verification purposes to improve flood management strategies.