Page 8 - Maquetación 1
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ABSTRACT



            Natural catastrophes related to floods are among those causing most casualties and economic loss. Different laws
            and regulations exist within European and State frameworks as well as for the autonomic one for risk management
            and mapping flood prone zones.
            Flood genesis is varied, hence there are different kinds of floods (natural/artificial, inland/coastal, flash floods/crues,
            in-situ floodings), and some of them might show their effects aggravated because of human activities (deforesta-
            tion, land movements, urbanization). The occurrence of floods in Spain allows differentiating four risk regions as-
            sociated to sudden floods in the Mediterranean region, to torrential floods in the mountain ranges, to crues in the
            middle and lower reaches of big peninsular rivers, and to waterloggin of flat and endorheic areas in the centre of
            big basins.

            Among the effects and impacts of floods it can be found: water depth and its durability, water velocity, erosion ca-
            pacity, sediment transport and deposition, and other associated geologic process (landslides, pipings).

            There are national and international examples and references that can be used as a guide for mapping risk and
            hazard of floods; there are also different sources of information for flood hazard and risk mapping such as carto-
            graphic (topographical, thematic, aerial photographs), alphanumerical (hidrometeorological and socioeconomi-
            cal) and fieldwork. Regarding the surveying methods, the following groups can be pointed up: historical-palae-
            ohydrological, geological-geomorphological and hydrology-hydraulics. All of them would rather be used in an in-
            tegrated way, calibrating and complementing one another. Considering the elements to be shown in the maps, these
            can be diverse as well as the way of graphically representing them; their inclusion would depend upon the scale,
            the method and the purpose for which the map is meant. Hazard can be mapped into three different zones (high,
            medium and low) where to establish use limits and restrictions. Further on, to develop these maps, several tools
            and programmes such as Geographic Information Systems can be used for hazard analysis, as well as for integra-
            ting risk factors.

            Last but not least, among the measures for mitigating risk, there exist predictive preventive or corrective measu-
            res, where the preventive non structural measure of spatial planning would rather be pointed up as the most ef-
            fective.




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