Author(s): M. Lompi; E. Caporali; M. Isola; B. Mazzanti

Linked Author(s): Marco Lompi, Enrica Caporali

Keywords: Flash flood events; Hydrologic modelling; Real events hyetographs; Small river basins; Design storm

Abstract: In order to test the response of a river basin to flash floods, the results of hydrologic models based on the 200 years design storm are compared with the ones based on real extreme events occurred in few subbasins prone to flash floods. The present work analyzes the hydrologic design in small river basins, which due to their size are prone to flash flood events. Particularly, the design made according to current technical regulations, based on the design storm of 200 years return period, could be not sufficiently precautionary when small river basins are considered. In order to explore if the peak discharges of extreme and short-duration events are greater than the one with return period of 200 years, a series of hydrologic modeling based on the hyetographs of real occurred events has been made on small river basins. At the first step a series of extreme and short-duration events occurred in recent years on the Arno river basin, in Italy, is analyzed, and the hyetographs of these events are reconstructed. In particular, the hyetographs have been scaled through the Areal Reduction Factors (ARF) in order to analyze the evolution of the phenomena also at the spatial scale. Based on the obtained hyetographs, a series of hydrological models have been carried out on a set of test river basins, in order to evaluate the flood hydrographs. For each river basin, the hydrographs of flash flood events have been compared with the ones with return period of 200 years, commonly used in the hydrologic design. The results have underlined how it is important, during the design phase, to combine the 200 years-flood event with the analysis of the response of a river basin to the hyetographs of flash flood events, especially when the river basin has a small area, i.e. less than 30 km2.

DOI: https://doi.org/10.3850/978-981-11-2731-1_348-cd

Year: 2018