Detection and analysis of shoreline changes using geospatial tools and automatic computation: Case of jijelian sandy coast (East Algeria)

Analysis and understanding of coastline variability and coastal erosion-accretion trends are important for scientists and local decision-makers for orienting regulation and decisions concerning coastal planning. This study focuses on the detection and analysis of historical changes in shoreline position of the Bay of Jijel (East -Algeria) occurred between 1960 and 2014. Shoreline changes along the Bay of Jijel were studied from multi-dated aerial photographs (1960, 1973 and 1988) and Quick-bird satellite image (2014). The correction of aerial photographs and satellite image was carried out using the remote sensing tools and Geographic Information System “GIS”. To attain our objective, the study area was divided into three sectors for analysis: (1) the beaches of Jijel, Tassoust in the western sector, (2) the central area encompasses beaches of El Kanar, El Mzair and SidiAbdelaziz, (3) the eastern sector contains the beaches of El Djnah and Beni Belaid. Net rates changes of shoreline position in time were calculated from several statistical methods End Point Rates (EPR), Linear Regression Rates (LRR) and Weighted Linear Regression (WLR). These net rates of coastline changes have been calculated, also, on three intervals of times (1960-1973, 1973-1988 and 1988-2014) and on a period (mid-centennial) of 54 years (1960-2014). The result shows that the study area is almost stable between 1960 and 1973 with a rate of change equal to −0.072 m/year. This rate of change, has negatively increased during episodes time 1973-1988 and 1988-2014, with average values of −0.125 m/year and −0.85 m/year, respectively. Over a mid-secular period, the coast has experienced an average net rate global of changes equal to −0.459 m/year. This recession of the coastline is due to the combined action of the cumulative effects of stormy climate of the coast and various human actions on the Jijelian coastal strip.