Detection and analysis of historical variations in the shoreline, using digital
aerial photos, satellite images and topographic surveys DGPS: Case of the
Bejaia bay (East Algeria).
Ayadi Katia*a, Boutiba Makhloufa, François sabatierbc and Guettouche Mohamed Saida
a
Departement of Earth Science, Geography and Territory Planning, Laboratory of
Geomorphology and Geohazard, Houari Boumediene University of Science and Technology
(U.S.T.H.B.), BP 32, El Alia, Bab Ezzouar 16111 Algiers, Algeria.
b
European Centre for Research and Teaching of Environmental Geosciences(CEREGE)
,BP80, 13545 Aix-en Provence CEDEX4,France.
c
Institute of Geographic Sciences and Spatial, University of Aix-Marseille 1, Avenue Robert
Schuman, 13100 Aix-en-Provence.
Abstract
The Bejaia coastline is one of the most beautiful and attractive coastlines in Algeria, this is
due to its landscape and ecological diversity running along it. The eastern coast of Bejaia is
formed by a wide stretch of sand, occupying the bottom of the bay. Its beaches are fed by
sediments carried by two main wadis that debouch into the bay: Soummam in the West and
Agrioun in the East. The undertaken work, in this article focuses on the study of coastal
erosion, which has a significant damage on the natural patrimony. This erosion risk in
perpetual evolution, by location, is dramatically affecting the beautiful sandy beaches and
various infrastructure over all the coast length of the Bejaia bay. In order to map and evaluate
this risk, a methodological approach has been followed. This approach is mainly based on a
diachronic variation analysis in the position of the shoreline over a period of sixty years;
based on a series of ortho-rectified aerial photos, satellite images as well as DGPS
topographic surveys on the ground. The results revealed significant variations in the position
of the shoreline during the last sixty years, especially on both sides of Soummam and Agrioun
wadis. The most observed retreat of the shoreline is in the western part of the coast, where the
rate of evolution reached -7.89 m/yr (beach of Sidi Ali Lebhar). Whereas; the shoreline retreat
reached -1.75 m/yr in the center of the bay and -2 m/yr towards the East.
Keywords: Bejaia bay; Coastline; Aerial photographs; Advance; Retreat; Coastal erosion.