Relation between climate and genesis of beach ridges and swales in the last 40 years (Cádiz, Spain)

Abstract

This work is a geomorphological study of the Doñana and El Rompido spits (Gulf of Cádiz), and an analysis of climatic and oceanographic data of this sector of the south Iberian coast, covering the last four decades. It relates the formation of beach-ridges and swales with the alternation of cyclonic and anticyclonic periods, and establishes one periodicity of around 3-7 years and another of 10-12 years. The former is related with short-term climatic events (NAO), and the latter, of greater morphological expression, with less intense sunspot activity. The frequent alternation of winter cyclonic regimes and summer anticyclonic regimes favours the formation of beach-ridges. Cyclonic periods are responsible for littoral erosive processes, making considerable amounts of sediments available in the shoreface zone. Swale genesis is related with anticyclonic regime with low erosion of the coast, resulting in little availability of sediments.