Hydrological simulation using a bivariate approach based on copulas for the assessment of inundation risk scenarios down-stream of flood control reservoirs

Abstract

Aim of this study was to assess operational reservoir rules for evaluating flood risk scenarios using a MonteCarlo bivariate framework. It involves a stochastic procedure to calculate flood hydrographs and, then, flood inundation area evaluation through a 2D hydraulic model to estimate the inundation risk and, as consequence, the relative damage evaluation, under different operation strategies of an upstream reservoir. The entire procedure can be summarised as follows: single synthetic stochastic rainfall events have been derived using a Monte Carlo proce-dure through a bivariate copulas analysis; synthetic bivariate stochastic inflow hydrographs have been derived by using a conceptual fully distributed model starting from synthetic hyetographs; flood hydrographs have been routed through the reservoir taking in account the initial level in the reservoir; flood inundation mapping through 2D hydraulic simulation and damage evaluation through depth-damage curves have been carried out. This al-lowed evaluating the influence of reservoir initial water level in the flood risk scenarios. The procedure was ap-plied to the case study of the floodplain downstream the Castello reservoir, located in the southwestern part of Sicily (Italy) and results demonstrate the framework’s potential and the effects of different water management scenarios on the flood risk of the downstream infrastructure.