GEOSCIENCE AND THE CONFLUENCE OF HUMAN-ENVIRONMENTAL INTERACTION IN PERI-URBAN DAKAR
Dakar, Senegal lies at the furthest western point of Africa and is home to over 2.5 million people in an area of only 550 km2. Its basaltic underpinnings facilitated a Quaternary tombolo that has experienced significant environmental contingencies in the process of rapid urban growth. The northern flank of the Cap Vert peninsula represents a unique geological setting of interdune depressions (called niayes) that are characterized by fairly fertile soils and accessible freshwater table. Subsequently, they are host to small, irrigated market gardens that supply up to 80 percent of the vegetables consumed by the urban center.
This area also constitutes the peri-urban fringe of Dakar where population growth and subsequent land use change has primarily been driven by rural to urban migration, underscored by climate change and disruption of traditional social values and interior farming traditions. The interface of population growth with the natural environment frequently contributes deleterious effects upon the ecosystem and its capacity to support valuable market gardens.
Urban structures within the Sahel are predominantly constructed of concrete, thus contributing to a high demand for cement and sand in the face of Dakar’s rapid and pervasive urban growth. An aggressive rate of coastal sand mining has led to pronounced erosion along the northeast coast and has resulted in acute damage to houses and the partial destruction of a swath of trees that had been planted to stabilize shifting sand dunes in order to protect the vital agricultural interests. Ecological integrity of the niayes is further threatened by salt water intrusion from water overdraw and from toxic leachate from the solitary urban garbage dump. These represent the more pressing contingencies from human-environmental interaction within this region. This paper shows the ameliorating potential of geosciences for vulnerabilities to market gardens in peri-urban Dakar.