Author(s): Dina Pirone; Luigi Cimorelli; Andrea D’Aniello; Daniele Martino; Domenico Pianese

Linked Author(s): Dina Pirone

Keywords: Chicago-storm; Variational Approach; Reservoir Routing; Peak-discharge; Dams

Abstract: Flood control reservoir design requires a combination of hydrological and hydraulic modelling techniques. Hydrological methods estimate the discharge from the basin upstream of the reservoir (i. e., inflow hydrographs), while hydraulic methods (reservoir routing) simulate how hydrographs propagate through the reservoir, thus computing the maximum outflow discharge and the stored water volume. This study investigates whether the use of specific hydrological methods may influence the evaluation of the maximum outflow discharge and stored water volume from reservoirs of different configurations. Under the ideal assumptions of linearity and stationarity in the rainfall-runoff process, two methods are compared: the Chicago Storm method and the Variational Approach. According to the convolution theory, the Chicago Storm method considers a single design hyetograph that converts the Identity Duration Frequency (IDF) curve into the design inflow hydrograph to evaluate the reservoir’s outflow discharge. Conversely, the variational approach considers several rectangular hyetographs with uniform intensity during the duration extracted from the IDF curves, transforms them into the corresponding hydrographs, and searches for the critical one that provides the maximum outflow discharge from the reservoir. The two methods are compared across 96 reservoir configurations characterised by varying outlet structures and geometries. Results indicate that the two methods produce similar estimates, with a mean percentage error between outflow discharge of less than 4 % and less than 20% in total stored volume. This preliminary result demonstrates that both approaches seem robust and reliable for the design of flood control reservoirs, although further evidence is required. Therefore, depending on the design process’s specific requirements or data availability, either method can be effectively utilised, offering flexibility in flood-control reservoir design.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P1975-cd

Year: 2025