A diachronic study of the Mediterranean coastline: A geometric approach

Fatima Zahra Salim,Mohamed Yassine El Habti,Khadija Ben Hamman Lech-Hab,Abdelkrim El Arrim,S Bourekkadi,K Slimani,J Abouchabaka,O Omari

doi:10.1051/e3sconf/202123400039

Abstract

Coastal areas represent one of the country's most important environmental and economic resources. They are naturally dynamic, with changes that can occur on a human time scale and that need to be quantified for the proper management of shorelines and, in particular, the beaches on which the local economy is largely based. This work focuses on the diachronic study of the coastline of the Mediterranean coast, particularly the coastal fringe at the mouth of the Wadi Aliane. In order to assess and remedy the risks of erosion and accretion of the coastline, the methodology followed consists of the application of automatic analytical techniques using multi-temporal photo-interpretation, a Geographic Information System (GIS) and a Digital Shoreline Analysis System (DSAS). The rate of change will be calculated from the multi-date maps, (1981- 1997 and 2016) using the End Point Rate (EPR) index. Comparison of the results of the interpretation of aerial photos and satellite images of the Oued Aliane coastline used (1981, 1997, and 2016) provided information that allowed us to understand the evolutionary behaviour of the wet sand/dry sand line over 36 years. This numerical analysis of the 1981 -1997 and 2016 coastlines in the coastal sector of Oued Aliane, shows us that zones A, C and D are mainly affected by erosion, while the mouth part is affected by accretion because it is considered a delta and therefore a sedimentation area.

Highlights

Morocco benefits from a coastal fringe that stretches over approximately 3500 km and in two coastal facades, Atlantic and Mediterranean
The diachronic study is based on photo-interpretation and the construction of a geographic information system (GIS) associated with a Digital Shoreline Analysis System (DSAS) Digital Shorline Analysis System and field observations and surveys
The result represents a synthesis of the coastal changes that have occurred since the 20th century in the coastline of Oued Aliane extending over a cumulative coastal line of almost 10 km

Summary

Introduction

Morocco benefits from a coastal fringe that stretches over approximately 3500 km and in two coastal facades, Atlantic and Mediterranean. The Moroccan coastline is the place where all the pressures of economic and demographic development combine and where competition for land is severe [1]. Coastal erosion is a global phenomenon caused largely by two factors: the reduction and sometimes even disappearance of sedimentary inputs to the coast, and eustatic movements. Morocco's coastlines do not escape this erosion. Within the framework of the country's sustainable development, it is essential to take it into account when developing tourism along the coast. The aim of this article is to understand the role played by anthropogenic developments, offshore dredging, as well as natural factors in the historical evolution of the coastline of the Oued Aliane, and to determine the areas of erosion and accretion. The diachronic study is based on photo-interpretation (aerial photographs, satellite images) and the construction of a geographic information system (GIS) associated with a DSAS Digital Shorline Analysis System and field observations and surveys

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Conclusion