The Senegal River is regulated by two dams, the Diama anti-salt dam constructed in 1986, close to the river mouth, and the Mantanali reservoir dam that was impounded two years later in Mali. The lower Senegal valley is characterized by a very low altitude, since the level at low water period reaches only 20 m in Kayes, a city currently located at 900 km from the river mouth. The mangrove vegetation that colonized the floodplain is a key point to understand the soil formation and evolution. In the Senegal valley, the climate is qualified as Cape Verdean up to 30 km from the Atlantic coast because of maritime influences, and then as Sahelian in the more continental part. Like most of the soils in the Senegal delta, the soil at N’Diaye is saline and generally acidic, due to the remains of pyrite or by-products, witnessing the ancient mangrove vegeta.