Coastal Vulnerability Index Assessment Along the Coastline of Casablanca Using Remote Sensing and GIS Techniques

This study explored the potential of Digital Earth Africa (DE Africa) coastline products for coastal vulnerability index (CVI) assessment. Although, CVI can be calculated from several dataset, objective of this study is to assess the CVI using remotely sensed data including the DE Africa coastline products and the Advanced Space borne thermal Emission and Reflection Radiometer Global Digital Elevation Model version 2 (ASTER GDEM), geological map, and geographic information system (GIS) techniques. The study has been conducted on the Atlantic coast of Morocco to evaluate the variability of the coastline of Casablanca from 2000 to 2023. The research was conducted by analyzing DE Africa coastline products namely annual shorelines and rates of coastal change along the Casablanca coastline. These products were used to extract coastal erosion metrics namely annual shoreline distances, shoreline change envelope (SCE), net shoreline movement (NSM), linear regression rate (LRR) and end point rate (EPR). The process involved the assessment of shoreline dynamics based on coastal erosion metrics and their variations especially for six main beaches located on the coast of Casablanca. These metrics were used in conjunction with information related to coastal elevation, coastal geomorphology and coastal slope, extracted from geologic map and ASTER GDEM, to compute the CVI in the GIS environment. The analyses of these datasets indicated that the major areas of Casablanca coastline, especially on the sand beaches, situated at elevation less than 12 m are threatened by the coastal hazards and are under pressure of coastal erosion at -1.5 m/yr rate. The results indicated that around 44 % and 23 % of the studied area have respectively a very high to high vulnerability index and they are vulnerable to natural phenomena such as inundation, coastal flooding and submersion, while 8 % and 25 % have respectively moderate and low vulnerability. This study showed that DE Africa coastline products combined with local landscape information constitute an invaluable tool for the studies of coastal monitoring.