Sand-spit evolution and inlet dynamics derived from space-borne optical imagery : is the Senegal-river inlet closing ?

With the majority of the world' population living in urbanised coastal zones, regional-scale coastal monitoring is a paramount tool to assess the risk exposure of local areas. At St. Louis, Senegal the coast experienced a recent acceleration in coastal erosion. Additionally, the sand-spit South of St. Louis is highly dynamic with one of the largest migration rates worldwide. In this study we showcase the use of satellite imagery to assess the morphological change of the St. Louis inlet position over more than 3 decades. The Senegal river inlet was artificially opened in 2003 Northward of its natural position. The effect of this opening is measured through local shoreline erosion and use of satellite data to predict the next closure of the Senegal-river inlet. Since the artificial breach coastal erosion at the fishmarket of St. Louis was measured, while the sand-spit initially accreted. Southerly sand-spit migration rates that varied from 475 m per year (before an artificial breach in 2003) to 590 m per year after the breach. With these migration rates and assuming limited changes in, for example, river run-off and wave environment, the inlet will close again around 2050 and 2055