Hydrogeophysical Parameters Estimation for Aquifer Characterisation in Hard Rock Environment: A Case Study from Yaounde, Cameroon

Abstract

Detailed local geological and hydrogeophysical investigations were carried out for the aquifer in Yaoundé, Cameroon to delineate the architecture of different subsurface geological horizons using lithologs and generated vertical electrical sounding (VES) data. An attempt has also been made to estimate aquifer transmissivity from resistivity data. The transmissivity of the uncon?ned aquifer was computed by determining the Dar-Zarrouk parameters (longitudinal unit conductance and transverse unit resistance) and were compared with the actual field transmissivity. The results showed a direct relation between aquifer transmissivity and transverse resistance. The relationship established has therefore, been generalized in the study area in order to evaluate hydraulic conductivity and transmissivity at all the points where geoelectrical measurements have been carried out. This generalization allows one to derive maps of the product K<i>σ</i> and transmissivity in the study area based on geoelectrical measurements. These maps are important in future modelling processes oriented towards better exploitation of the aquifers

GIS-Hydrogeochemical Model of the Yaoundé Fractured Rock Aquifer, Cameroon: Aquifer Setting, Seasonal Variations in Groundwater-Rock Interaction and Water Quality

“…From field observations, borehole lithostratigraphic sections and by comparing various case studies in similar terrain in gneiss-type rocks and in some parts of Yaoundé have indicated that topography controls groundwater flow and that base flow to rivers is an important factor moderating groundwater movement in Yaoundé as shown here by the groundwater contours for four seasons (Teikeu et al, 2016;Wyns et al, 2004;Clark, 1985;Acworth, 1987;Obiefuna & Sheriff, 2011;Fouépé Takounjou et al, 2012). Lithologies from their VES curves corroborated the lithologs of boreholes from this area (Teikeu et al, 2012). Some researchers have concluded with a dual aquifer conceptual model for fractured rock gneiss aquifers (Teikeu et al, 2012;Wyns et al, 2004).…”

“…Lithologies from their VES curves corroborated the lithologs of boreholes from this area (Teikeu et al, 2012). Some researchers have concluded with a dual aquifer conceptual model for fractured rock gneiss aquifers (Teikeu et al, 2012;Wyns et al, 2004). Although weathered gneiss terrains are layered, aquifer models suitable for sedimentary terrains of layered formations cannot apply here where the fissures and fractures cut across the layering in the formations' regolith that still retain relics of the continuous gneiss fractures and fissures intact in saprolite, weathered basement and fresh fractured basement.…”

“…Although a comprehensive hydrogeological investigation has not been made heretofore of the whole city of Yaoundé, many researchers have carried out works on selected groundwater topics and in parts of Yaoundé. Notable amongst them are: Flow dynamics of lineaments in Yaoundé (Teikeu et al, 2016); mass balance of Nitrogen and Potassium in parts of Yaoundé (Kringel et al, 2016); assessment of groundwater quality for domestic and irrigation purposes in parts of Yaoundé (Tabue et al, 2012); use of geoelectric tools to explore the lithostratigraphy of the aquiferous formations in parts of Yaoundé (Teikeu et al, 2012); assessment of bacterial contamination in the Mfoundi Watershed (Kuitcha et al, 2010) and modeling of groundwater flow in Yaoundé IV district (Fouepe et al, 2011).…”

Estimation of Hydrological Parameters from Geoelectrical Measurements

“…On the other hand, Kazakis et al [12] obtained linear relations between the K and the resistivity of the aquifer. Some authors have found a linear relationship between T and T R [16][17][18][19]. The works of these authors suggest that there is a relation between the transmissivity of an aquifer and the parameter of Dar-Zarouk, also that this relation is influenced by the geo-hydrological conditions of the place and maintains an exponential relation.…”

“…In this work, we are experimenting in the search for exponential relations between R o and R w ; T and K with the electric transverse resistance. The transverse resistance is one of the Dar-Zarrouk parameters and has been proved to be useful in the evaluation of hydraulic conductivity and transmissivity [14][15][16][17][18][19][20]. In a flat and stratified earth model, each geoelectric layer is characterized by a thickness h and an electrical resistivity ρ.…”