Evaluation de la biomasse végétale permanente et saisonnière dans les communes côtières ouest de Mostaganem à l’aide des SIG et télédétection.

Abstract

Mostaganem's western coastal zone (study area) is characterized by an urban concentration and a variety of economic activities, including agriculture, industry, transport (land and sea), fishing and green and seaside tourism. The geomatics approach adopted involved the use of GIS and remote sensing tools to diagnose environments (physical, biotic and abiotic) and map land use. GIS processing methods applied using ArcGis software (version 10.8) to eight (8) 1:25,000 topographic maps (1989) and a 30m DEM (2000) were used to delimit the area of interest and characterize its relief. The remote sensing methods involved using ArcGis software to generate six (6) vegetation index images from six (6) Sentinel-2 images acquired between January and August 2024. Other images such as Bing Microsoft and images archived in Google earth Pro. were used to refine the interpretation of the satellite images. Analysis of the results shows that the western coastal zone (study area) is administratively delimited by four (4) coastal communes (Fornaka, Stidia, Mazaghrane and Mostaganem). It covers a total area of 18,400 ha with a coastline of 48.5 km. Its relief is gently sloping. The land-use map shows that vegetation surfaces (agriculture, forest and halophilic vegetation) are more important than mineral surfaces (bare soil, urban areas and associated facilities). At the end of January 2024, planted areas occupied a total surface area of 15,129 ha (82% of the zone's total), of which 23% was forest. Between the months of January and August 2024 (8 months), the vegetated area decreased by 8,810 ha (48% of the total area) due to the seasonal cycle of crops. Mineral surfaces have doubled (2) more than plant surfaces, due to the increase in bare soil surfaces after seasonal harvesting. This loss of vegetation increases the risk of erosion, reduces oxygenation of the environment and reduces carbon sequestration.