Author(s): Amparo Sanchis Plasencia; Alfonso Cavalle Garrido; Onofre Gabaldo Sancho

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Keywords: Flood risk management; Digital terrain model; Hydrological studies; Hydraulic studies; Flood hazard and risk maps; Floods Directive

Abstract: This paper will show specificities and interesting aspects of adapting the European Directive to highly torrential rivers in the Mediterranean region including its impact in the territorial planning of coastal dense populated areas. The most important tool for decision support is the improvement of knowledge. In this sense, the elaboration of flood hazard and risk maps at the appropriate scale is the basic tool for flood risk management through the application of existing regulations. This is especially relevant in Mediterranean coastal areas, as the irregular regime of Mediterranean rivers increases the occupation of river space, with disastrous consequences for people, the economy and the environment. The process for the elaboration of this mapping is technically complex, and requires the development of specific studies involving a multidisciplinary team: - Hydrology is the starting point. Calibrated hydrological studies are not always available. It is therefore necessary to use robust contrasted methodologies or the elaboration of ad-hoc studies that allow their calibration, with the aim of obtaining the maximum flows associated with the different return periods studied. - Reality evolves continuously, so the preparation of the maps must be a living process. In this sense, the elaboration of digital terrain models is a fundamental task. Currently, PNOA LiDAR information is used for the elaboration of DTMs. However, this information has to be processed and corrected through field and desk work, especially in densely populated areas with strong human impacts. - The hydraulic models that allow the maps to be obtained are difficult to calibrate and validate. The main objective of hydraulic modelling is to delimit the floodplains for different return periods in the studied area. This will also make it possible to know the depths and velocities reached, and the preferred flow areas. When there are flood plains through which the overflowing flows will flow, and in addition the human impact adds elements that laminate or retain the flow, is necessary to perform two-dimensional hydrodynamic models. - From the results of the hydraulic modelling, the flood areas, the prefered flow areas and the public hydraulic domain with its associated zones (police and easement) are obtained. The cross-referencing of the hazard maps with the different vulnerable elements in the territory makes it possible to obtain flood risk maps. In this way, information can be obtained on the risk to the population, to economic activities, to points of special importance such as schools, hospitals, etc. or to natural elements of environmental importance. Flood hazard and risk mapping is fundamental as it allows the application of current regulations for territorial and urban planning in flood-prone areas

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221371

Year: 2022