Résumé
178
Assessment of the vulnerability of zemmouri bay to coastal erosion, diachronic study
between 1957 and 2017
Nour el Imène Mouhoubi (1)* , Rabah Belkessa (1)** , Housseyn Otmani (1)***
(1) Ecole Nationale Supérieure des Sciences de la Mer et de l’Aménagement du Littoral
university campus ofdély Ibrahim, bois des cars, dély brahim 16320, Algiers, Algéria.
* : correspondonce author : Tel : +213 (0)777262124 et mail : nour.mouhoubi@gmail.com
** : mail: belkessarabah@yahoo.fr
*** : mail : otmani.housseyn@gmail.com
Abstract:
Coastal change on sandy shores occurs at a variety of spatial and temporal scales. Gaining
knowledge of beach change processes increases our ability to manage coastal erosion risks
that affect the growing population living in coastal areas. This study focuses on detecting and
analyzing historical changes in the shoreline position of Zemmouri Bay (Northern Algeria)
between 1957 and 2017. The evolution of the coastline along the bay was studied from aerial
photographs (1957, 1957, 1973, and 1988), google earth satellite images (2006, 2011, and
2016), and DGPS (Differential Global Positioning System) topographic surveys of 2012, 2015
and 2017. The correction of aerial photographs and satellite images was performed using
remote sensing tools. The study area was divided into six sectors to achieve our objective.
Then, net rates of change in shoreline position over time were calculated using several
statistical methods: End Point Rates (EPR), Linear Regression Rates (LRR), and Weighted
Linear Regression (WLR). These changes were measured for several time intervals and over a
global period (1957e2017). The results revealed significant differences in shoreline position
over the past 60 years, mainly on both sides of the Isser Wadi. The most observed coastline
retreat is located in the eastern part of the coast, where the rate of change has reached -
1.25m/year (Mazer Beach East), while the retreat of the coastline was above -1m/year in the
center of the bay and -0.50 m/year towards the west. Over a mid-century period, the coast has
experienced an overall average net rate of change equal to -1.35m/year. This coastline retreat
is due to the combined action of the cumulative effects of the climate on the coast and various
human activities on the coastal strip of Zemmouri.
Keywords:
DSAS – Shoreline – GIS – Erosion – Accretion
1.Introduction
The evolution of the coastline is a natural phenomenon generated by the conjunction of
processes (marine, continental and biological). It depends on the characteristics
geomorphologic features of coastal systems (beaches are more sensitive to erosion than
cliffs). However, these natural phenomena are exacerbated by anthropic actions that disturb
178
Assessment of the vulnerability of zemmouri bay to coastal erosion, diachronic study
between 1957 and 2017
Nour el Imène Mouhoubi (1)* , Rabah Belkessa (1)** , Housseyn Otmani (1)***
(1) Ecole Nationale Supérieure des Sciences de la Mer et de l’Aménagement du Littoral
university campus ofdély Ibrahim, bois des cars, dély brahim 16320, Algiers, Algéria.
* : correspondonce author : Tel : +213 (0)777262124 et mail : nour.mouhoubi@gmail.com
** : mail: belkessarabah@yahoo.fr
*** : mail : otmani.housseyn@gmail.com
Abstract:
Coastal change on sandy shores occurs at a variety of spatial and temporal scales. Gaining
knowledge of beach change processes increases our ability to manage coastal erosion risks
that affect the growing population living in coastal areas. This study focuses on detecting and
analyzing historical changes in the shoreline position of Zemmouri Bay (Northern Algeria)
between 1957 and 2017. The evolution of the coastline along the bay was studied from aerial
photographs (1957, 1957, 1973, and 1988), google earth satellite images (2006, 2011, and
2016), and DGPS (Differential Global Positioning System) topographic surveys of 2012, 2015
and 2017. The correction of aerial photographs and satellite images was performed using
remote sensing tools. The study area was divided into six sectors to achieve our objective.
Then, net rates of change in shoreline position over time were calculated using several
statistical methods: End Point Rates (EPR), Linear Regression Rates (LRR), and Weighted
Linear Regression (WLR). These changes were measured for several time intervals and over a
global period (1957e2017). The results revealed significant differences in shoreline position
over the past 60 years, mainly on both sides of the Isser Wadi. The most observed coastline
retreat is located in the eastern part of the coast, where the rate of change has reached -
1.25m/year (Mazer Beach East), while the retreat of the coastline was above -1m/year in the
center of the bay and -0.50 m/year towards the west. Over a mid-century period, the coast has
experienced an overall average net rate of change equal to -1.35m/year. This coastline retreat
is due to the combined action of the cumulative effects of the climate on the coast and various
human activities on the coastal strip of Zemmouri.
Keywords:
DSAS – Shoreline – GIS – Erosion – Accretion
1.Introduction
The evolution of the coastline is a natural phenomenon generated by the conjunction of
processes (marine, continental and biological). It depends on the characteristics
geomorphologic features of coastal systems (beaches are more sensitive to erosion than
cliffs). However, these natural phenomena are exacerbated by anthropic actions that disturb