Author(s): Angeles Diaz Cano; Cristina Puertes Castellano; Felix Frances Garcia; Onofre Gabaldo Sancho

Linked Author(s): Cristina Puertes Castellano

Keywords: Flood risk management; Distributed hydrological model; Hydraulic studies; Flood hazard maps; Floods Directive

Abstract: This paper will show the specific work developed in the south of the metropolitan area of Valencia to obtain flood hazard maps at the appropriate scale for decision-making in territorial and urban planning, in a highly populated area with very significant human impacts. As part of the implementation of the Flood Risk Management Plan for the Jucar River Basin, TYPSA has carried out a review of the flood hazard maps of the Poyo and Picassent basin for the Júcar Hydrographic Confederation, and its main tributaries, a system that has a Mediterranean torrential regime and flows into the Albufera lake, a site of high ecological value, crossing very vulnerable areas due to the high population that resides in them and the economic importance of the uses affected. The methodology follows the methods and criteria set out in the Methodological Guide for the Development of the National Floodplain Mapping System (Ministry of the Environment and Rural and Marine Affairs, 2011). This methodology was adapted to the characteristics of the area and the availability of data. To this purpose, a detailed hydrological and hydraulic analysis was carried out, taking into account previous hydrological studies and the improvement of digital terrain models. Due to the singularity and problems of this areas, it is essential to use a distributed hydrological model that allows us to consider the spatio-temporal variability of rainfall, as well as to obtain hydrographs at any point of interest. For this purpose, the TETIS distributed hydrological model has been used. For its implementation, rainfall information from the SAIH-CHJ and AEMET networks (1990-2018) was used, identifying the October 2000 event as the maximum extraordinary event, which was adopted as the calibration event. For its validation, a temporal validation was carried out with the rest of the identified events (smaller and with different duration and antecedent humidity conditions). After the implementation of the hydrological model, 100 synthetic storms were generated, representative of the possible spatio-temporal variability of precipitation in both basins. These storms were simulated with the hydrological model implemented, considering two antecedent humidity states (dry and wet), which made it possible to obtain 200 hydrographs at the points of interest. Finally, a statistical analysis of extremes was used to calculate the return period associated with each of the 200 hydrographs for each point of interest. This made it possible to select the set of events representative of the return period to be studied for each point of interest. The different hydrographs corresponding to the selected sets of events were used as input data for the two-dimensional hydrodynamic modelling with HEC-RAS, obtaining different flood hazard maps for each event. The final flood hazard maps correspond to the envelope of all of them

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221374

Year: 2022