Adzope's Municipal Artificial Lake which serves as a drinking water supply to the population is prone to pollution due to human activities and increasing urbanization. Thus, it is essential to protect this surface water supply for sustainable use. The objective of this study is to determine the protection zones around this water reservoir in order to preserve the stored water quality. To achieve this, a methodological approach based on a Geographic Information System (GIS) was adopted. This methodological approach first consisted to assess the water reservoir vulnerability to pollution according to certain hydrological parameters (slope, land use, soil type, runoff, and drainage network density) and then to determine the protection zones according to the different vulnerability classes. After the scoring of different parameters, a weight was assigned to each, from the multi-criteria method (AHP). The combination of the weighted parameters in the GIS enabled to establish the water reservoir vulnerability indexes map. The vulnerability map established subsequently presents five (5) vulnerability classes in the watershed: very low (12%) and low (23%) in the North and South of the study area, moderate (32%) disseminated throughout the study area, high (20%) and very high (13%) particularly in the West and North of the water reservoir and in the East of study area. This water reservoir vulnerability map is potentially influenced by the land use parameter according to the sensitivity analysis test. The different vulnerability classes then allowed the delimitation of three protection zones (Zone 1, Zone 2 and Zone 3) around the water reservoir. The immediate protection zone (Zone 1) has a width between 100 and 450 m around the water reservoir with *Geographic Information System for protection zones delineation around a surface water resource.

The lagoon that is the subject of this study, was chosen as drinking water alternative source of supply for the city of Abidjan. However, this language is shown in a very favorable area of forest to agriculture. We observe large rubber plantations, food and oil palm crops spread throughout the lagoon basin. Also, fertilizers injected into these plantations, as well as releases from industries and homes they are potential sources of pollution of the lagoon. According Humbert (2012), this pollution is reflected in particular by widespread concentration of nitrates and pesticides. Given these observed problems related to the quality of this resource, this study was initiated. Its objective is to develop a methodology based on the functionality of a Geographic Information System (GIS) to assess the degree of threat to what the Aghein lagoon faces through the completion of a vulnerability map at pollution. The method used here is a spatial analysis model incorporating several parameters including the slope, land cover, soil type, runoff and drainage density. These parameters have been previously defined, prioritized and weighted, and then integrated into a GIS. The resulting map shows five classes of vulnerability indices to pollution of the lagoon Aghein. They are: very small classes, low, medium, high and very high. These indices highlight the areas from which the lagoon is threatened.

<p>This study is being carried out on the Abidjan groundwater, the exploitation of which has made it possible to equalize the price per cubic meter in Côte d'Ivoire. However, the quality of these waters is increasingly tested by various sources of pollution, particularly the dumping of toxic waste in 2006.</p><p>With a view to ensuring an effective water supply for the people of Abidjan, this study aims to develop a decision-making tool to protect the water table against pollution. To achieve this objective, it was necessary to model the transport of dissolved perchloroethylenes through the water table using the Feflow code. Various data were used to develop the conceptual model and the input parameters for the groundwater flow model coupled with the transport.</p><p>The calibration of the flow model allowed us to obtain an NRMS = 4.77%, revealing the convergence of the model which was furthermore verified by the modification of the number of meshes. The model was then used for predictive simulations of dissolved perchloroethylene transport at the five selected waste disposal sites. The simulation of the transport of perchloroethylene allowed the horizontal trajectory of the pollutant within the Continental Terminal slick to be understood. The contamination times vary from 9 to 47 years. This study undoubtedly favours the sustainable management of groundwater resources in the District of Abidjan by resolving accidental or point source pollution problems.</p><p>Key words: Pollution, Abidjan groundwater, modelling, transport, perchloroethylene, Feflow, Abidjan District.</p>