Résumé
194
Fig. 15Evolution of the coastline of Zemmouri Bay from 1959 to 2021
The retreat of the coastline is detectable on practically all the stations except for some
localized in Cape Djinet and Boumerdes. The intensity of the recession is very different from
one site to another. But, given the margin of error admitted during the manipulation of aerial
photographs estimated at +/- 0.5 meters and given the duration of the monitoring of the
coastline (60 years), an ambiguity exists as to the reliability of the values of the net rate of
change less than 0.05 meters per year. Thus, of the 38 stations studied, three have uncertain
values that are difficult to discern on the scale of an aerial photograph.
The overall trend for the entire Bay coastline reveals that over the 60 years (1957-2017), 42%
of the coastline is eroding, i.e., 21.5 km of coastline, compared to only 21% accreting, i.e.,
almost 11 km of linear coastline; stable areas account for only 37% with a distance of 19 km
located at the level of promontories and rocky regions (Fig. 16).
Fig. 16The general tendency for all transects of the study area between 1957 and 2017.
The method used in this study appears to be an effective tool for assessing shoreline position
changes along microtidal coastlines. This study revealed that shoreline change detection can
be done using corrected aerial photographs, high resolution satellite data, and DGPS surveys
-4
-3
-2
-1
0
1
2
3
4
5
6
El
Marsa
El
Marsa
center
01
El
Marsa
center
02
Zerzouria
Ain
Beida
Tamaris
kef
el
Arrar
Ain
Taya
Blue
waves Surcouf Deca
plage El
Tarfaia El
Tarfaia El
Kaddous Reghaia
West Reghaia
East Chatt Chatt Boudouaou
El… Corso
West Corso
East Boumerdes Boumerdes Rocher
Noir 800
logements… Rocher
Pourri Figuier
West Figuier
East Sghirette Zemmouri
West Zemmouri
East
01 Zemmouri
East
02 Mazer
West Mazer
East Mazer
East Djenat
Familial Djenat
01 Djenat
02
37%
42%
21%
Global results between 1957-2017
stable
erosion
accretion
194
Fig. 15Evolution of the coastline of Zemmouri Bay from 1959 to 2021
The retreat of the coastline is detectable on practically all the stations except for some
localized in Cape Djinet and Boumerdes. The intensity of the recession is very different from
one site to another. But, given the margin of error admitted during the manipulation of aerial
photographs estimated at +/- 0.5 meters and given the duration of the monitoring of the
coastline (60 years), an ambiguity exists as to the reliability of the values of the net rate of
change less than 0.05 meters per year. Thus, of the 38 stations studied, three have uncertain
values that are difficult to discern on the scale of an aerial photograph.
The overall trend for the entire Bay coastline reveals that over the 60 years (1957-2017), 42%
of the coastline is eroding, i.e., 21.5 km of coastline, compared to only 21% accreting, i.e.,
almost 11 km of linear coastline; stable areas account for only 37% with a distance of 19 km
located at the level of promontories and rocky regions (Fig. 16).
Fig. 16The general tendency for all transects of the study area between 1957 and 2017.
The method used in this study appears to be an effective tool for assessing shoreline position
changes along microtidal coastlines. This study revealed that shoreline change detection can
be done using corrected aerial photographs, high resolution satellite data, and DGPS surveys
-4
-3
-2
-1
0
1
2
3
4
5
6
El
Marsa
El
Marsa
center
01
El
Marsa
center
02
Zerzouria
Ain
Beida
Tamaris
kef
el
Arrar
Ain
Taya
Blue
waves Surcouf Deca
plage El
Tarfaia El
Tarfaia El
Kaddous Reghaia
West Reghaia
East Chatt Chatt Boudouaou
El… Corso
West Corso
East Boumerdes Boumerdes Rocher
Noir 800
logements… Rocher
Pourri Figuier
West Figuier
East Sghirette Zemmouri
West Zemmouri
East
01 Zemmouri
East
02 Mazer
West Mazer
East Mazer
East Djenat
Familial Djenat
01 Djenat
02
37%
42%
21%
Global results between 1957-2017
stable
erosion
accretion