The improvement of the conditions of access to drinking water for the populations of the Lobo watershed requires the exploitation of groundwater because of the surface water which remains exposed to climatic hazards and the impacts of anthropic activities. And yet, these underground waters finds himself bedrock aquifer which are complex aquifers. Thus, the objective of this study is to characterize those fissure aquifers that who govern underground run-off in the aquifer system of the Lobo catchment area. The methodology adopted consisted in using 1A sentinel radar images to map fractures and their spatial distribution. The validation of the lineaments first consisted in comparing and highlighting the lineaments from the radar images and the fractures revealed from photo-geological images. Next, we superimposed the map of lineaments on the map of boreholes with a flow rate greater than or equal to 5 m3/h, which were considered as productive boreholes. To determine the traffic corridors, this fracturing map was superimposed on the piezometric map. This work made it possible to extract 9,753 lineaments over a surface area of 7,000 km². The various validation techniques enabled us to confirm 121 major fractures with an average length of 9 km. In addition, the most productive boreholes are located on average less than 300 m from the fractures. The analysis of the distribution of the orientations of these fractures revealed a heterogeneity of direction and a predominance of the N-S; NW-SE and NE-SW families. The Fracturing density maps and density of the number of fracture crossing points highlight the spatial heterogeneity of the fracture network which is controlled by geomorphology, geological formations and lithological contacts. The river Lobo and its main tributary the Dé, flow preferentially in fractures. This river and its tributary drains the aquifer system. The results obtained from different thematic maps are useful for the realisation of future high-yield hydraulic wells (Q ≥ 5 m3/h).

Water is a precious natural resource that is essential for many uses, but its quality is faced with several problems, including pollution linked to human activities, hence the need to contribute to improving the quality of drinking water. Given the importance of the resource, the health of the population in terms of hygiene needs and the quality of the water consumed is paramount. It is within this framework that this work falls within the scope of this project, the objective of which is to analyze the health impacts to which the populations are exposed due to the use of water in the Lobo watershed in Nibéhibé. To achieve this objective, the working method was based on literature review and field surveys. The documentary research consisted in circumscribing the contours of the subject in order to better understand it. As for the field surveys, they were dominated by interviews and a questionnaire addressed to households and health structures. Using the simple random selection method without discount and the use of a statistical equation, we found a sample of 384 households to be surveyed, distributed in three departments (Daloa, Vavoua and Zoukougbeu). Population surveys, combined with spatially referenced data under GIS, made it possible to assess not only the spatial distribution of the importance of water-related diseases, but also the areas at health risk. The results highlighted health risk indicators that expose households to water-related diseases linked to the mode of water supply. Also, the contraction of these diseases by households is due to the uncontrolled use of multiple uses and the risky behavior of the population with regard to hygiene and sanitation practices. In addition, we note that those in rural areas are the most affected because of the insufficient level of access to drinking water and adequate sanitation. Thus, these diseases cause great loss of human life and contribute to the disorganization of the social structure.

Water is a vital resource for all populations. However, there are warning signs that the water from the Lobo River used by SODECI to supply drinking water to the population is declining in quantity during the dry season and its quality is becoming poor due to climate variability and anthropogenic activities. However, the river is able to maintain a certain flow, probably with the contribution of groundwater. It is therefore a question of whether there is really a connection between surface water and groundwater. The aim of this study is to characterize the groundwater-river interactions based on the physico-chemical parameters of the Lobo watershed in Nibéhibé. The approach adopted is a coupled statistical-geochemical approach applied on data from two sampling campaigns (dry and rainy season). This coupled approach consisted, on the one hand, in understanding the chemical specificities within the water classes using the piper diagram and, on the other hand, in classifying the waters according to their physico-chemical similarity and highlighting the phenomena at the origin of the water mineralization using the Kohonen self-organized map (SOM). The results obtained from the piper diagram show that in both the wet and dry seasons, the chemical signature of the waters remains controlled by two main hydrochemical facies: the chlorinated calcium-magnesium nitrate hydrofacies and the bicarbonate calcium-magnesium hydrofacies. Kohonen's self-organized map has established that the mineralization of groundwater, under natural conditions, comes from the nature of the rocks crossed during infiltration and from the contact time between water and minerals. This work provides managers with decision-support tools for planning and searching for groundwater in support of surface water to reinforce the drinking water supply of the populations in this watershed.