The human impact on the Espinho-Paramos coast in the 20th Century

Abstract

The relationship between man and coast has been for centuries marked by a “peaceful coexistence”, something which has been neglected over the last generations. The evolution of the coastline does not depend solely upon natural factors but also upon the type of intervention and land use of man. The “advances” of the sea along the Portuguese coastal strip are not recent; however the maintenance of the position of the coastline using engineering structures to protect the coast from the intervention of the last generations has contributed significantly to an increase of erosion and related problems. This paper describes an analysis demonstrating the influence of engineering structures on the evolution of the coastline by comparing and integrating information from cartographic documents and newspaper reports, which constitute the best source of information for the area under study. The analysis was conducted using cartography at different scales and from different sources over about a century, which allow us to estimate the advances and retreats of the coastline and determine changes in terms of the behaviour of the coastal strip in stabilised stretches. Coastal erosion has been affecting the study area since the end of the 19th century and its increasing impact has been felt throughout the 20th century. The several experiences and projects of coastal protection adopted during the 20th century have not prevented the retreat of the coastline and they have in fact become ineffective, contributing to the amplification and propagation of the phenomenon, especially from the 1970s onwards, to the south sector of the study area, where erosion rates in the period 1998/2003 ranged between 1,5m/year and 5m/year. The average coastline retreat is 2 m/year, which demanded the need to maintain and reinforce protective structures, which means an expense of millions of euros during a period of a century constituting an economic and environmental loss.