Etude De L’évolution Du Trait De Côte À L’aide De L’outil Mobitc : Cas Du Littoral De Grand-Bassam

This study proposes an assessment of the historical coastline (TDC) mobility of the Ivorian coastline, specifically the Grand-Bassam coastline (Côte d'Ivoire), and suggests reflections on the sustainable management of the coastal environment in Côte d'Ivoire, taking into account coastal erosion. The objective is to evaluate, using the MobiTC software, the spatio-temporal and statistical evolution of the morphology of the Grand-Bassam coastal zone in order to plan appropriate coastal developments. Specifically, it is to extract images on google earth, to treat them under MobiTC and to analyze the rate of spatio-temporary and statistical evolution of coastlines. To do this, data from QuickBird images provided by Google Earth from 1984, 1988, 1992, 1996, 2000, 2004, 2008, 2012 and 2016 in the study area were used. Different software was used for image processing. The ENVI 5.1 software allowed georeferencing and thresholding to make the images superimposable and highlight the baseline. The digitization of the images was done with ArcGis software. The QGIS 2.18 software was used to convert the .shp files to the mid / mif format of the MobiTC software. The latter makes it possible to understand the statistical evolution of the coastline dynamics from the creation of a baseline, the skeleton of envelopes and traces. The variations observed between 1984 and 2016 show a fattening of 0.23 m / year in some sectors and an erosion rate of 0.34 m / year in other sectors. It is noted that 62.79% of the coastline is accretion and 37.21% is eroding

Assessing potential coastal flood exposure along the Port-Bouët Bay in Côte d’Ivoire using the enhanced bathtub model

Coastal flooding is a growing concern for many communities worldwide due to climate change. This study focuses on the Port-Bouët Bay, located in Abidjan, Côte d’Ivoire. A coastal flood model based on the enhanced bathtub model was used to map the present and future flood extent and assess exposure to quantify the likely affected populations, buildings, and land uses for different scenarios. The model incorporated a digital elevation model, surface roughness, flood water source, and the once a century extreme sea-level scenarios. Validation was conducted against GPS coordinates of recently flooded zones. The analysis revealed that, under current conditions, around 21.58 hectares are vulnerable to flooding, and approximately 2465 people and 544 buildings are exposed to flooding today. Based on future projections, the extent of flooding is anticipated to increase by different ranges depending on the time period and the climate change conditions. By the end of the century, the increase in flooding extent could reach a percentage of 27%, 37%, and 90% under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. The impacts would consequently be worsened with greater number of people and assets exposed to future coastal flood hazard. The land use analysis showed that informal settlements are the occupation most exposed, followed by residential settlements, commercial and industrial land, in that order. The spatial disaggregation of this exposure across neighborhoods indicates that Sogefiha is the most exposed, followed by Petit-Bassam and Vridi. However, a substantial increase in coastal flooding in Vridi by 2100 under the SSP5-8.5 scenario could lead to significant exposure level change for this scenario. This information is critical for evaluating and managing present and future coastal flood risks in the Port-Bouët Bay area and for informing decision-making processes