Groundwater resources in Sub-Saharan Africa are promoted by development organisations as reliable alternatives to ensure water supply for human consumption and agricultural use. National efforts to map and monitor groundwater quality and quantity, however, are not adequate to promote sustainable groundwater management. Within a technical cooperation project, the Federal Institute for Geosciences and Natural Resources (BGR) supports the intergovernmental Niger Basin Authority (NBA) and its nine member states to establish groundwater-monitoring networks, map the quality and quantity of the groundwater resources, and elaborate tools for groundwater management.
The paper presents a reassessment of the groundwater resources of the southern Iullemmeden Basin derived from the combination of archival data and recent measurements within the AGES monitoring network. To improve the limited coverage of national databases, the technical cooperation project strives towards the valorization of so-far neglected grey literature and archival data including, among others, the groundwater appraisals of the mid-20th century as well as available reports of (inter-) national development projects.
A major challenge for the harmonization process is the differentiation of the multi-layered aquifer system of the Iullemmeden and the assignments of wells to one of the aquifer storeys of the Continental Terminal (Ct1-3) and the Continental Intercalaire/Hamadien. Unreliable lithological and technical profiles together with the usual tapping of multiple aquifer storeys to increase productivity limit the use of both archival and contemporary measurement data for the characterization of defined groundwater levels.
To create a consistent conceptual (hydro-)geological model, a general reassessment/revision of borehole lithology and stratigraphy became necessary. We explore the geostatistical approaches to discriminate groundwater bodies based on water chemistry, hydraulic head, and isotope data to improve the original lithostratigraphic classification.
Valorization of archival data – with the respective thorough quality checks – is underestimated provides necessary baseline data for groundwater management.