Objective: The objective of this study was to develop and apply an optimization model for the sizing of detention reservoirs in an urban watershed, aiming to minimize implementation costs and mitigate flood risks in critical areas. Theoretical Framework: The study is based on flood control models and urban drainage infrastructure, focusing on optimization techniques applied to water resource management. References include the SCS Curve Number method for surface runoff, the PCSWMM hydrological model for precipitation simulations, and the HEC-RAS hydraulic model for flood area delineation. Method: The research was divided into three main stages: (i) physical and hydrological characterization of the watershed using PCSWMM; (ii) delineation of flood-prone areas with HEC-RAS 2D; and (iii) development of a nonlinear optimization model in GAMS for the sizing of detention reservoirs. The decision variables included the height, surface area, and outlet diameter of the reservoirs, with implementation cost as the main objective function. Results and Discussion: The optimization modeling determined the ideal characteristics of six reservoirs distributed throughout the watershed to maximize retention and flow control. The total flooded area was estimated at 270,989 m², with maximum depths reaching 1.914 meters. The total cost of the reservoir system was calculated at approximately R$ 1,164,845.91, providing an optimized solution for flood control in the watershed’s vulnerable areas. Research Implications: The results suggest a practical and feasible solution for flood control in urban watersheds, offering a replicable model that can aid in planning drainage infrastructure in other regions facing similar challenges. Originality/Value: This study is original in its integrated application of PCSWMM and HEC-RAS models with a nonlinear optimization approach in GAMS, resulting in an efficient and economical solution for flood mitigation in urbanized areas.
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