Datación de avenidas torrenciales y flujos de derrubios mediante metodologías dendrogeomorfológicas (barranco de Portainé, Lleida, España)

Abstract

García–Oteyza, J., Génova, M., Calvet, J., Furdada, G., Guinau, M., Díez-Herrero, A. 2015. Dating flash floods and debris flows through dendrogeomorphological methodologies (Portainé stream, Lleida, Spain). Ecosistemas 24(2): 43-50. Doi.: 10.7818/ECOS.2015.24-2.07 Dendrogeomorphology is a very useful tool in the scientific-technical analysis of floods and debris flows in high mountain streams, where conventional sources of data (discharges or rainfall) are scarce or non-existent and certain social problems arise. The Portainé stream, whose head the eponymous ski station Port Aine (Lleida, Spain), meets these characteristics. Erosional and depositional phenomena associated mainly with periods of heavy summer rains, periodically affect the access road to the ski station, which crosses the stream at various points, with consequent economic losses and personal and services potential danger. This work aims to estimate, by dendrogeomorphological techniques, the number and time distribution of floods and torrential flows into the stream, to evaluate if anthropogenic interactions in the hydrographic network, associated with the opening and operation of the ski station and its access, may have changed their frequency. Tree specimens exhibiting obvious external damage caused by the impact of materials dragged through the torrential floods were sampled. A detailed geomorphological study was also conducted and the historical data available were compiled. With all this information a database of past flood events for a period of 50 years was generated, which has resulted in a significant increase of these events in recent decades.