Simulating the impact of medicane “Daniel” in an urban catchment using a 2D integrated flood simulator

The medicane Daniel occurred in early September of 2023 and hit several countries of the Mediterranean area with catastrophic consequences and thousands of fatalities. Specifically in Greece, the event can be divided in two phases: a) the flash floods observed mainly in the catchments near Volos city and b) the fluvial flooding of Pineios river after two days due to the levee failures in several points, which were stressed due to the increasing water stage of the river. In this work, we focus only on the first part of the event, simulating the flood impact in the catchment which drains through Volos city and has an area of 33.5 km². We used the physics-based 2D integrated flood simulator SERGHEI in a High-Performance Computing environment, since the simulation is characterized by increased computational burden. For the rainfall, we used two sources of meteorological data: a) a satellite-based ERA5 reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF); b) a synthetic rainfall based on the statistical processing of the data recorded at the meteorological stations of the Hellenic Integrated Marine Inland water Observing, Forecasting and offshore Technology System (HIMIOFoTS), coupled with the Intensity-Duration-Frequency (IDF) curves of Greece. In order to perform a plausible check regarding the modelling efficiency, crowd-sourced information is collected from social media and compared with the SERGHEI outcome.