Development of an integrated coastal management tool for rocky coasts at the algarve study site

Abstract

Coastal erosion has contributed throughout geological time to shape world coastal landscapes leading to the coastline that we know today. This natural phenomenon, allied with soil erosion in water catchments, is the source of sediment for costal systems such as beaches and marshes. These systems have several purposes and functions serving as wave energy absorbents, habitats and nesting grounds for fauna and flora, maintaining also a barrier and protection between the fresh and saltwater. Coastal systems have been proven to be very desirable places for humans that led to increasing migration of the human population towards them due to the resources that could be obtained from these areas, from fishing to industry. In Europe, the settlement of a large population on these areas, heavy exploration and the touristic high demand for coastal areas increased interference and turned erosion into a serious problem, with ever growing negative consequences, especially along the French, Spanish, Portuguese coasts and the southern coast of the United Kingdom. Although most of the population realizes that the coastal erosion is a problem that needs to be addressed, their focus is mainly on short-term based observations of a rapid erosion. Therefore, other options must be considered and made known to the public, governmental and scientific communities.

In order to study and create solutions for the coastal erosion and management plans adjusted to the processes of the rocky coastlines, the case study site was the southernmost rocky coast of the Algarve region. The Algarve rocky coast displays a very crenulated physiography mainly where the intensively karstified Lagos-Portimão Formation is exposed (between Porto de Mós and Olhos de Água). Beaches occur at the cliffs’ foot separated by headlands often connected to shore platforms forming littoral cells. Currently, the survival of these beaches depends almost exclusively on the longshore drift due to the lack of sediment sources from inland transported by rivers. The erosion of cliffs has minimal contribution in this area because rocks are mainly carbonates therefore the artificial nourishing of beaches has been an increasingly frequent practice.

This thesis intends to contribute to the knowledge and identification of the main factors which are most relevant to the sustainable management of the coast, with emphasis on rocky coasts. It is structured in eight chapters. Chapter 1 encompasses an introduction to the general concepts and terminology needed to understand the several chapters from geomorphology terminology to mathematical equations. Chapter 2 a general overview of the characteristics of the study area and in chapter 3, a background analysis on coastal planning, legislation and legal instruments is carried out to assess how Portugal is dealing with EU demands. In chapter 4 the conditioning factors of geomorphological record are analysed and in chapter 5 management tools applicable to the rocky shores worldwide are proposed. The latter two chapters give insights of parameters that should be considered in coastal management and tools to achieve it. In chapter 6 socio-economic interactions with coastal areas are analysed in order to relate the state of tourism with the issues that need to be overcame in coastal areas. In chapter 7 the findings of this study are discussed, and the scientific progress and management recommendations are presented. In chapter 8 the overall conclusions are presented and the scientific outputs of this study.

In short, this thesis provides a review of the state of EU coastal policies and shows good examples of the benefits of using new technologies and methodologies in coastal regions, creating new cartography and indexes to identify important parameters for the rocky coast of the Algarve. It contributes to the understanding of the diverse morphological coast of Algarve and the several issues that may be found when trying to achieve an integrated coastal management approach.

The main objectives were achieved. This study establishes a scientific knowledge basis for an integrated management of rocky shores by highlighting the most important factors that influence erosion, creating models and frameworks adapted to their specific features and to the fast-increasing human pressures. The acquired data and scientific outcomes contribute to a diverse range of topics providing guidelines and tools for future researchers and coastal managers to achieve a more sustainable coastal management plan.