Monitoring and forecasting of coastal erosion in the context of climate change in Saint Louis (Senegal)

This study examines coastline change along the Langue de Barbarie (LB), the sand spit at the mouth of the Senegal River that shapes erosion dynamics in Senegal's Saint Louis region — one of the country's most vulnerable areas to coastal erosion owing to its distinctive physical and socio-economic characteristics. A central driver of these dynamics is an artificial breach opened in 2003: initially just 4 m wide and intended to mitigate flooding, sediment dynamics expanded it to 6 km by 2020, affecting the entire region. Using Geographic Information System (GIS) and remote sensing techniques, the study analyses coastline change across three zones of the spit (LB-1, LB-2, and LB-3) over the period from 1994 to 2042, tracing how the breach reshaped shoreline behaviour and projecting future change.

The results show a marked shift in coastal dynamics following the breach. Before its creation, average dynamic rates in zones LB-1, LB-2, and LB-3 were estimated at 4.4, 5.9, and 4.4 m/year respectively; afterward, they shifted to -1.2, 8.4, and -2.7 m/year, with the most severe erosion observed along LB-3 at -6.6 m/year during 2002–2012. Projections for 2032 anticipate erosion rates of -11.5 m/year in LB-1 and -26.8 m/year in LB-3, alongside accretion of 8.41 m/year in LB-2, with eroded areas totalling 571,458 m² against 67,191 m² of accumulation. By 2042, erosion is expected to intensify further — reaching rates of -23 and -53.6 m/year and producing 1,021,963 m² of eroded area versus 94,930 m² of accumulation, with a dynamic rate of 168.2 m/year in zone LB-3. These findings carry significant implications for addressing the urgent problem of coastal erosion along the Langue de Barbarie.