Nuevas metodologías en la evaluación de la peligrosidad y el riesgo por avenidas en cuencas de montaña

• Autores: V. Ruiz Villanueva
• Directores de la Tesis: Andrés Díez Herrero (dir. tes.), José María Bodoque del Pozo (dir. tes.)
• Lectura: En la Universidad Complutense de Madrid ( España ) en 2013
• Idioma: español
• Títulos paralelos:
  • New methods for the analysis of flash flood hazard and risk in mountain basins
• Tribunal Calificador de la Tesis: Guillermina Garzón Heydt (presid.), David Uribelarrea del Val (secret.), Gerardo Benito Ferrández (voc.), José Anastasio Fernández Yuste (voc.), Varyl R. Thorndycraft (voc.)
• Materias:
  • Ciencias de la tierra y del espacio
    • Geología
• Enlaces
  • Tesis en acceso abierto en: Docta Complutense (pdf)
• Resumen

  • The physiographic and climatic characteristics of mountain areas determine the hydrological processes which occur in their basins. These characteristics also affect whether they are prone to flash floods. Floods of this type show flashy hydrographs w hich reach their peak within hours or even minutes after heavy rainfall or sudden snowmelt; they occur in small basins (of up to a few square kilometres in area), with very short response times, leaving very little advance warning. These flash floods may trigger the mobilization of varying amounts of solid load (debris laden sediment and woody material), altering the dynamics and morphology of the stream bed. In terms of potential risk, the transport and deposition of this solid load may signifi cantly increase the impact of the flash flood. Cross-sectional obstruction may reduce the stream bed area; e.g. at bridges obstructed by woody material. Flash floods are also seldom recorded by the conventional instrumented networks of rain gauges an d stream gauges; this is because of the space-time rainfall variability in mountain areas and also because the gauge networks are usually installed in low-lying areas in the main river networks. All of the above are why flash floods are linked to the highest death tolls in Europe from flooding. The main objective of this research paper is therefore to develop new methods to improve flood risk evaluation in mountain areas. First, the data from different instrumental, historical, documentary and d endrogeomorphological sources was integrated to compile and characterize past flash-floods and include this combined information in frequency analysis. The woody load was then included in the flash-flood hazard and risk analyses. In spite of the sign ificant impact of the presence of this type of load on fluvial dynamics, it is seldom taken into account in flood studies. To allow this factor to be included, a numerical model was developed to simulate the woody material transport in conjunction wi th the hydrodynamics. Finally, the uncertainty at each stage of the risk analysis (flow rate estimate, frequency analysis, hydrodynamic simulation and vulnerability assessment) was evaluated from a probabilistic viewpoint. This methodology was implem ented in various basins or river reaches in the Sierra de Gredos (Spanish Central System). The results obtained confirm that dendrogeomorphological techniques are a powerful tool which can be used to obtain and date the chronology of past floods and