Dinámica geomorfológica del frente costero del Valle de Teixidelo (no Península Ibérica) entre 1945 y 2014

Abstract

The dynamic of a cliff sector has been studied (A Capelada, Galicia, NW Iberian Peninsula) as a site of a great interest due to its geological, geomorphological and landscape constitution. The most singular feature is the presence of cliffs with 612 m, split perpendicularly by small valleys opened by failures. These are flat-topped cliffs that surpass, in most of the sectors, the 32º of slope, reaching in some places 88º. The study area, focused in the Teixidelo Valley, whose distal sector had a movement over 25 m between 1956 and 2014. The paper analyses (i) the geomorphological evolution of the valley considering a wide temporal range, and (ii) the causal factors of the valley movement. Working method consisted in a geomorphological evolutionary analysis using photointerpretation techniques. This was divided in two phases, the first one aimed at the acquisition and preparation of data (aerial images and meteorological and oceanographic data) and, the second, focused on the analysis procedure.

The results indicate that the study area is an old landslide, with a valley bottom moving at an average rate of ~0.4 m/year, a movement/temporal sea ratio of 0.6 m/temporal sea and another of episode heavy rains/year of 0.5. The genesis of this movement was attributed to the erosion of the coastal front with temporal sea and the associated instability that causes the basal distension. The presence of episodes of high precipitation intensity and its effect on the clays present in the valley, favor the sliding of this. The Teixidelo Valley represents an example of coastal dynamics in which many factors interact, making difficult to delineate cause and effect, operating with a certain random load, although more dominated by moments of high intensity and low frequency.