Measuring the Total Economic Value of Traditional Sand Dredging in the Coastal Lagoon Complex of Grand-Nokoué (Benin)

Abstract

Sand is a crucial resource for society's development. Among the most exploited sand quarries in the world are the lagoon and wetland sand. Although mechanical sand dredging is the most spread technique, manual and traditional techniques are still widely used in West Africa. The purpose of this paper is twofold: to describe traditional sand dredging (TSD), highlighting the procedure used and the structural organization of this activity, and to evaluate the total economic value of TSD in order to help decision making about wetland management. Therefore, TSD occurring in the coastal lagoon complex of Grand Nokoué (CLCGN) in Benin was investigated. Field surveys indicate that TSD is mainly dominated by men, about 93% of the actors. It required intense physical efforts including diving to the bottom of the lake and removing manually the sand in backed toward the surface of the water. TSD actors are organized in local associations which deliver extraction license and discuss with both the others actors and the local government. The total economic value of the benefits of TSD to the population, estimated using direct market value and replacement cost, was estimated at 2.44 million USD per year for 127,818 m 3 of sand extracted. It is clear that introduction of mechanical sand dredging will increase the amount the sand removed and subsequently will increase some benefits such as reduction of flooding amplitude and mitigation of the filling of the lakes. However, mechanical sand removal will also considerably reduce the profit the local population makes from sand commerciali-zation which currently represents 80% the total economic value of TSD.