OUVRAGES DE CAPTAGE DEAU ET PERIMETRES DE PROTECTION: CAS DES NOUVEAUX CHAMPS CAPTANTS DE DJIBI ET DE NIANGON NORD II A ABIDJAN (COTE DIVOIRE)

To strengthen the drinking water supply capacity of Abidjan city, the State has built water catchment structures in the communes of Cocody-Angre and Yopougon-Niangon Northern-2. However, in the proximity of these structures, there are several human activities that constitute major sources of pollution. It is therefore necessary to implement a strategy to protect this resource. Thus, this study aims to determine the close (PPR) and distant (PPE) protection perimeters around these catchment structures. The analytical methods of Krijgsman and Lobo-ferreira and Wyssling were used to determine the protection perimeters. For the PPR, the values obtained with the Krijgsman and Lobo-Ferreira method vary from 118 to 155 m for the upstream radius and 42 to 79 m for downstream radius. While those obtained with Wyssling vary from 107 to 144 m for upstream radius, and 50 to 87m for downstream radius. At the level of the PPE, the results vary from 1,128 to 1,721 m for upstream radius and 47 to 109 m for downstream radius according to the Krijgsman and Lobo-Ferreira method. Those calculated with the Wyssling method varying from 4,084 to 4,199 m for upstream radius and 93 to 207 m for downstream radius. Concerning the radius perpendicular to the flow direction at the borehole, it varies from 74 to 112 m for PPR and PPE with Krijgsmans and Lobo-Ferreiras methods. While Wysslings method gives 74 to 112 m for the PPR and 615 to 933 m for the PPE respectively. The Wyssling method therefore better evaluates the radii of the protection perimeters of Abidjan groundwater catchment structures.