Morphological and evolutionary classification of sandy beaches in Cadiz coast (SW Spain)

Abstract

Del Río, L., Gracia, F.J. and Benavente, J., 2013. Morphological and evolutionary classification of sandy beaches in Cadiz coast (SW Spain).Sandy beaches are extremely dynamic systems, so gaining insight about decadal patterns of beach change is essential for the adequate management of risks affecting coastal zones. This work aims at improving understanding of the factors that control erosion-accretion processes and evolution of sandy beaches at the intermediate time scale. For this purpose, recent evolution of beaches along the 150 km long Atlantic coast of Cadiz (SW Spain) is investigated in relation to their morphology and dynamics. Dune toe and high water line changes are assessed based on georectified aerial photographs from 1956–2008, using GIS tools. Results show considerable spatial and temporal variability of recent shoreline changes along the study area, with mostly eroding trends along the northern sector and a predominantly stable southern sector. Important exceptions at certain points are related to the heterogeneity of the coast and the diverse natural and anthropogenic factors contributing to shoreline change in the area. A classification of the studied beaches is proposed, based on beach morphology and dynamics, thus helping to understand the way coastal morphological characteristics influence erosion-accretion trends. Rectilinear beaches are predominantly stable or accreting, whereas reef-supported beaches are mostly erosive. Z-bays generally experience erosion at one end and accretion at the opposite end, greatly influenced by local conditions. Enclosed beaches are stable where sediment budget remains unchanged, but rapidly erode or accrete if human interventions alter the balance. The classification allows identifying those beaches which are most sensitive to variations in controlling factors, such as sediment supply.