This study aims to estimate the groundwater storage change of hard rock aquifers in the face of change. For this, the approach developed consisted initially in the implementation of 5 Magnetic Resonance Soundings (MRS) around the observation wells realized and monitored from 2014 to 2015 in the Sanon experimental site. In a second step, we determined the storage change using the MRS data and the water table fluctuation method. The MRS data show that the water content varies spatially from 4.5 to 1.3%. The maximum value is recorded at the central valley where a piezometric dome is observed. The specific yield varies from 2.4% in the central valley to 1.3% at the outlet. The renewed water resource is estimated at 116 mm in the central valley and 32 mm at the outlet, which corresponds respectively to 13 and 3% of the annual rainfall. The renewed water resource is consistent with the annual recharge. Thus, the combination of the MRS geophysical approach and water table fluctuation method is an efficient, fast and cheaper (compared with long-term pumping test) tool for the estimation of groundwater storage changes.

The present study aims at understanding the role of the structure and the geometry of the weathering profile on the hydrodynamic behavior of hard rock aquifers. We first described 2D geophysical cross sections of weathering profiles realized and validated on an experimental site. Next, we implemented five long-term pumping tests in wells drilled at various locations of these cross sections. Finally, we chose the appropriate analytical solutions to determine the hydrodynamic parameters in consistence with the structure and the geometry of the weathering profile. Results reveal that land covers, weathering type and thickness, presence of no flow boundaries, etc. are all factors that explain the flow regime, which appears therefore much less unpredictable. In other words, the 2D geophysical data are enough to locate the best permeable areas, or the areas where the structure of the aquifer without impervious boundaries and with leakage favor a good long-term behavior of the well. The values of aquifer’s transmissivity vary between 5.10⁻³ and 4.10⁻⁵ m²/s. The storage varies between 0.06 and 7.10⁻⁷. The variability of these parameters from site to site reflects the high heterogeneity of hard rock aquifers.

Introduction: The use of geotextiles is now well established in the field of civil engineering, particularly in geotechnics, where they serve a range of functions including drainage, filtration, separation, reinforcement, protection, and erosion control. For over three decades, these materials have played a key role in the design and long-term performance of infrastructure. The development of geotextiles made from natural plant fibers, especially those derived from kenaf, represents a promising advancement that offers both economic and environmental benefits. This study aims to evaluate the mechanical and hydraulic properties of woven geotextiles made from kenaf fibers sourced from Nérékourosso, as well as their effectiveness in reinforcing road foundation layers. Methods: Two types of geotextiles were produced by weaving, with mesh openings of 0 mm and 5 mm, respectively. Mechanical characterization tests were carried out, along with static puncture resistance and normal-to-plane permeability tests. CBR load-bearing tests were performed to evaluate reinforcement efficiency depending on the geotextile’s position in the foundation layer. Mechanical tests showed higher tensile strength in the cross direction for the geotextile with no mesh opening (17.19 kN/m) compared to the 5 mm mesh type (2.90 kN/m). Results: The closed-mesh geotextile withstood a maximum puncture load of 1170 N, versus 540 N for the open-mesh variant. The 0 mm mesh geotextile exhibited a surface flow rate of 2200 L/min/m ² . CBR tests indicated better performance for the 5 mm mesh geotextile, especially when placed at mid-height within the reinforced layer. Discussion: These results suggest that while the closed-mesh geotextile offers superior intrinsic mechanical properties due to its dense structure, the open-mesh variant performs better in soil reinforcement applications, likely because its structure allows better interaction with surrounding materials and more effective stress distribution. Conclusion: Kenaf-based woven geotextiles show promising potential for road foundation reinforcement, with mesh configuration significantly influencing performance.