GEOMORPHOLOGICAL CONSEQUENCES OF FREQUENT AND INFREQUENT RAINFALL AND HYDROLOGICAL EVENTS IN PYRENNEZ MOUNTAINS OF SPAIN


    loading  Checking for direct PDF access through Ovid

Abstract

Various aspects of pluviometric and hydrological events have been studied worldwide, one of which is the geomorphic hazards as the intensity of the events exceeds various geomorphic thresholds. During the last few years, rainstorms of different intensities have occurred in the Central Spanish Pyrenees, including one of exceptional character. Large, historical debris flows have been studied, as well as the actual sediment transport in small experimental catchments. This study shows that during the most frequent events suspended sediment transport is the common geomorphic process. Bedload is mobilized several times per year while small rock avalanches and channelized debris flows have a return period of at least 5 years. Hillslope debris flows are triggered by rainfall events with a 25–30 year return period. Reactivation of large, deep mass movements is linked to rainfalls of around 100 year return period (between 130 and 160 mm in 24 hours). Catastrophic geomorphic processes occur when precipitation exceeds a 100 year return period, as was the case of the Biescas campsite disaster. Geomorphic processes triggered by intense rainfall events have caused major damage and human disasters but the hazards have been reduced by the introduction of several control measures, including reforestation, the construction of check-dams, canalization of river segments and improved flood forecasting.

    loading  Loading Related Articles