Comparative hydrodynamic study of granitic and sedimentary catchments in Western Niger. Issue 10 (27th July 2021) - Malam Abdou, Moussa
ABSTRACT: This study aims to compare hydrological processes in the Liptako-Gourma crystalline basement and the Iullemeden sedimentary zone in Western Niger. These two sites were equipped to quantify water infiltration, runoff and water retention within the beds of the ravines. We found that for the same surface type, while hydraulic conductivity was similar in both sites, surface runoff was 15–50% higher in the crystalline site compared to the sedimentary site. Within the sedimentary basin, we assume that runoff mainly originated from the tiger bush (typical vegetation and bare soil stripes found on plateaus). We suggest that the main reason for differences in stream flow was the stream storage capacity, which was four-fold higher in the sedimentary area compared to the crystalline domain. We thus conclude that the crystalline area functions as a water production and draining zone whereas the sedimentary basin is an accumulator of this resource.