Flood Hazard Assessment in a Mountainous River Basin in Thessaly, Greece, Based on 1d/2d Numerical Simulation

Floods are amongst the greatest natural hazards in the world. In the last decade, many flood events have been observed and recorded in Greece, which have had a direct effect on river ecosystem consistency. Flood hazard assessment is a critical parameter for flood hazard areas identification and for taking relevant mitigation measures to prevent the hazard. Therefore, the study and evaluation of streams’ hydraulic behaviour is necessary for flood management. The aim of this research work is to present a substantial methodology for flood hazard management based on GIS and hydrological/hydraulic numerical models. Flood inundation and flood hazard maps in a stream area under steady and unsteady flow conditions, using one–dimensional and two–dimensional flow models were generated, as an extension of the European Directive 2007/60/EC. For unsteady flow simulations, a hydrograph was used, based on the available rainfall data of the flood occurrence period. The simulation under steady flow conditions was performed for return periods of 100 and 1000 years. Numerical results of one–dimensional and two–dimensional numerical models were adequately compared with available field measurements providing the reliability of the current methodology