Effects on flood hazard in Marathon plain from the 2009 wildfire in Attica, Greece

Abstract

In August 2009 a wildfire in northeast Attica, in Greece, burned approximately 187 square km of forest and agricultural land, inducing significant damages in properties and infrastructure. The fire extended in 19 hydrological basins affecting substantially the hydrological processes in the area and raising significant questions about changes in their flood risk regime. In this work, possible changes in peak discharge and the total runoff volume after intense rainfall, due to the wildfire effects in Charadros and Rapentosa catchments in Marathonas, Greece, are investigated. The results showed that peak discharge resulting from the 50-year return period design storm will be increased between 13.8% and 19.8% in Rapentosa and Charadros. Peak flow rate resulting from the 100-year design storm will increase between 11.4% and 16.7% in the two basins. Total runoff volume presents an increase of 9.5% to 16.7% in the two catchments depending on the storm scenario. Furthermore, it is shown that a new probability regime has been introduced, as discharges connected with storms with annual probability of 1%, before the fire, will now require storms of 1.6% annual probability of occurring in Charadros and 1.3% in Rapentosa.