Flood risk determination through hazard, exposure and vulnerability analysis in the city of Salamanca (Spain)

More and more population is exposed to flood risk due to the increase in urban density, cities expansion through riverside areas and also higher incidence of extreme phenomenons. Then, simulating these risks will be of great help in developing planning and resource management preventive actions. In this case, a process of evaluation of the danger, exposure and vulnerability of the population and its assets regarding the floods in the Tormes River in Salamanca is established, using as a base the programs HEC-RAS, HEC-GeoRAS and ArcGis. We studied four return periods with different probability of occurrence and intensity, corresponding to 5, 50, 100 and 500 years. The flow rates corresponding to each period were calculated, with the extension, speed and depth that would be achieved in each case. The danger of each event is also obtained from the depth and speedt. Regarding the exhibition, the infrastructures and buildings that would be flooded in each case are identified, quantifying their length or number respectively. The vulnerability of the different buildings and infrastructure exposed is determined according to their characteristics. The conjunction of the three factors determines the flood risk.