Risk Assessment and Bidasoa Watershed Management Plan (PAP014712)

Código

PAP014712

Autores

Javier Dominguez Espluga, Elena Martínez Bravo, Gloria Robles, Miguel Angel Arrabal, Eduardo García Salete, Ana Castiella, Luis Sanmartín, Fernando Mendoza Rodriguez, César Pérez Martín

Tema

Urban Floods

Resumo

The Bidasoa watershed has suffered many floods. The most destructive were: 1913, 1953, 1983, 2007 and we now have to add 2009 and 2011. Thus, it has been analyzed and evaluated on several occasions by various bodies, on different scale, scope and boundaries. This study seeks to analyze the flooding risks, and to establish measures to write the Management of Flooding Risks Plans (PGRI) of the 7 ARPSIs that the watershed encompasses, responding to the Royal Decree 903/2010 on watershed flooding risk assessment and management, transposing the Directive floods (2007/60/EC), while defining the legal zones of the Modification of the RDPH (RD 9/2008), i.e. DPH, Extreme Damage Zone, Intense Outflow Way and Preferred Flow Area, updating the Civil Protection Risk Areas, as well as the characteristic (defined by damages) flows, analyze the Risk Assessment by Zones according to the criteria set-out by the Navarra Government according to the flood characteristics for the Territorial Management Plans (POT), the analysis of other pending proposals as well as other structural and non-structural measures of local risk abatement such as enlargement of hydraulic capability. The study's scope are the main courses of the Bidasoa watershed on Navarra territory, totaling 104 km of river course, and 625 square km watershed. 1. Analysis of historical events and precedents All information in databases and GIS. 2. Geomorphological study, (orthophotos of 1929, 1956, 1984, 2010), 3. Pluviometric study: Regional analysis of the flood index on 60 pluviometers 4. Hydrological Study: Phoronomic study, total of 75 sub-watersheds, 5. Treatment of LIDAR cartography on flood zones. Course correction by batymetrics. 6. Hydraulic study: model used GUAD 2D. 7. Hazardousness analysis according to RD 903/2010 and characteristic flows. 8. Risk analysis according to POT criteria. 9. Management plan: Exposition of means: evacuation routes, SAT, etc... As a result maps, GIS, databases, documents, and others tools have been produced conducive to the goals. Main conclusions: ? The influence of the hietogram, and the comparison between a unidimensional preliminary and a bidimensional study. Advantages and disadvantages. ? Cartography's impact: advantages of LIDAR and the problems generated when it does not correspond to the hydraulic demands in breaklines and flood plains. This enquiry has produced essential information, and illuminated the need for calibration of the hydrological and hydraulic models. ? The Bidasoa watershed is defined by steep slopes, where any significantly level terrain, sloped at less than 3%, lies in the lowest parts of the river valley, and is almost completely within the flood plain. Therefore population, infrastructure and services are concentrated in the alluvial. ? The largest structural measures are already in place. The most efficacious to be considered will encompass the future planning of settlements, according to the criteria of the Navarra Government, the SAT SAD SAIH, and taking into account the concentration times of the river beds, and specific rain emergency thresholds, as well as the resiliency measures of buildings, conurbations and roads, and the surviving structures.