Mapping the unintended Socio-Ecological Costs of Sea Defence in Ghana

Coastal protection through sea defence construction has become a dominant adaptation response to coastal erosion in Ghana. However, growing concerns suggest that these interventions may inadvertently trigger new socio-ecological risks, including displacement and loss of livelihoods. This study aims to assess sea defence–exacerbated the impacts in form of displacement and dispossession of coastal populations in two critical sites in Ghana namely Blekusu–Agavedzi in the Volta Region and Glefe–Chemunaa in the Greater Accra Region. Multi-temporal high-resolution satellite imagery covering the period from 2010 to 2024 was acquired from Image Hunters and processed using ArcGIS Pro (version 3.5). The imagery underwent pre-processing to correct for geometric and radiometric distortions. Subsequently, images were digitized and classified into five key land cover categories: bareland, built-up areas, water bodies, vegetation, and beach zones, using a combination of manual digitization and semi-automated classification techniques. Change detection analyses were then conducted to quantify spatial transformations over time. These geospatial analyses were complemented by community participatory mapping and drone surveys, which provided on-the-ground validation and insights into local experiences of displacement and livelihood disruption. Findings reveal a significant loss of beach area due to intensified erosion, severely affecting fish landing sites and coastal livelihoods. Additionally, a substantial number of residential buildings, schools, and cemeteries were destroyed or relocated, highlighting the profound social and cultural costs of hard-engineered coastal defences. The study advocates that future coastal defence planning must account for the full spectrum of socio-ecological impacts to ensure equitable and sustainable outcomes for vulnerable coastal populations.