Caractérisation De L’aquifère Superficiel Du Bassin Sédimentaire De Kandi (Nord-Est Bénin, Afrique Ouest): Nature Et Structure Du Reservoir, Hydrodynamique (original) (raw)

This article deals with the characterisation of sedimentary Kandi basin, in particular its hydrogeological structure and hydrodynamic functioning, which are still poorly known, precisely in its superficial part captured by European Scientific Journal, ESJ ISSN: 1857-7881 (Print) e - ISSN 1857-7431 January 2021 edition Vol.17, No.3 www.eujournal.org 81 exploitation boreholes and directly concerned by the impact of climate variability and change. The analysis of the structure of the basin's aquifer system was carried out by geological and hydrogeological correlation of existing borehole logs. The hydrodynamic study was carried out by considering existing test pumping data and two piezometric measurement campaigns (August 2016 for high waters, then April 2017 for low waters). The results confirm the essentially sandstone and conglomeratic nature of the lithology of the two layers captured by the hydraulic boreholes, namely, depending on the sector, the continental Wèrè formation (CambroOrdovician) and the marine Kandi formation (Upper Ordovician to Lower Silurian). The water tables of these two more or less permeable formations, which are directly superimposed on each other, are hydraulically interconnected to form a single groundwater table. The values of hydrodynamic parameters calculated show that transmissivity of the aquifer system ranges from 3.08E-02 to 2.99E-04 m²/s, and permeability ranges from 1.30E-04 to 3.37E-05 m/s. Groundwater flow is generally from South to North, in accordance with the regional dip of the layers and tectonic.