Different types of flooding lead to different human and material damages: the case of the Lisbon Metropolitan Area

Abstract

In this study, both human and material damages caused by different types of flooding in the Lisbon Metropolitan Area (LMA) were determined for the first time. Human damages (fatalities, evacuated and displaced people) were obtained from the DISASTER database (1865–2010 period). Material damages’ estimation was obtained from the Portuguese Association of Insurers database for the period 2000–2010. A classification of types of flooding based on the hydrological/physical features of the territory separating fluvial floods (slow and flash floods) from urban flooding (related and unrelated to the ancient natural drainage network—FREN and FUNN) was used. Topographic maps from the nineteenth and twentieth centuries (1:10,000 and 1:25,000 scales), information from newspapers and daily rainfall data were used to define this classification and to validate the flooding occurrences. It was concluded that: (1) during 146 years, 131 flooding events with human damages occurred in the LMA; (2) 120 flooding events with material damages were registered in 1781 places for 11 years; (3) the spatial distribution of human and material damages was very different; (4) each type of flooding caused distinct human and material damages; (5) the importance of each type of flooding varied over time due to human interventions in the territory; (6) there is a clear decrease in the mortality associated with flooding even during the extreme flooding events. This study contributes for spatial planning and insurance companies, allowing to define the temporal evolution and spatial patterns of the types of flooding, as well as to understand their future damages.