Many villages in the Casamance river mouth in Senegal suffer from coastal erosion, leading to loss of homes, working space for fishermen, and salt water in agricultural fields. Permeable groynes made of sticks and palm leaves were constructed by the inhabitants, started by a local initiative.

Indicated issues

Coastal erosion

For large parts of Senegal, the rising Atlantic Ocean, buildings and concrete dykes protecting villas and hotels all along the coast between Dakar and Saloum, and erratic water conditions are rapidly growing problems that are causing extreme coastal erosion. Uprooted trees, demolished houses, collapsed cliffs and loss of livelihood and revenues: residents at the Casamance river mouth are experiencing it all. As a result, many young inhabitants are migrating to larger cities.

Goals

Ensure a secure future

Three scientists, concerned about the damage to coastal communities, decided to work together: an economist, a specialist on the West African coastline and a hydrologist with knowledge of the region and the terrain. Their goal is to ensure a secure future for young people in a village where livelihoods from artisanal fishing and small-scale agriculture are threatened by erosion. Improved livelihood security will hopefully prevent large-scale migration to cities.

Solutions

Permeable groynes

The solution is the construction of permeable wooden groynes made of sticks and palm leaves. These reduce the waves and current and sand to be deposited, widening the beaches and provide more security for inhabitants. The contruction started in 2022 and was a community effort: 100 young adults of the village of Diogué in 8 teams constructed the groynes in a festive setting. Women were also actively involved in the construction of the groynes. Due to the use of local materials and regular maintenance over time, it is necessary to ensure that communities have a good understanding of the erosion phenomenon and the permeable wooden groynes.

Results

40 meters

The permeable groynes techniques that were borrowed from a distant geographical area (Canada) seem, in most cases, capable of stopping and then reversing the trend of the retreat of the coastline. So far, 40 meters on the sea all along the coastline of 1 kilometer are regained. The groynes trap the sand thanks to the filtering carried out by the stakes and leaves. The application of such a practice must be carried out methodically, proceeding in stages in order to understand the impact of the groynes according to local characteristics and taking the time to observe each stage.

At the project site a new symbol is created: coconuts trees are planted on the line that was reached by erosion, symbolizing that the sea will not return.

Valuation of solution

The implementation of permeable groynes to combat erosion is a cheap and easy solution that can be implemented with the help of inhabitants. Furthermore, the regular publication of the work on the gizc.org website has enabled to establish fruitful relationships with many professionals internationally.