eng Science and Education Publishing American Journal of Water Resources 2333-4819 2024-04-08 12 2 39 52 10.12691/ajwr-12-2-2 AJWR20241222 article Tamonkem Adzeh Roger tamonkemroger@gmail.com 1 Kemgang Dongmo Tchouta 1 Mvondo Valentin Yvan Emmanuel 2 Iwoudam Ma?vow Edmond 2 Ngounou Ngatcha Benjamin 2 The University of Ngaound¨¦r¨¦ - Faculty of Science - Department of Earth Sciences - P.O. Box 454 Ngaound¨¦r¨¦ Agricultural Research Centre of Maroua, P.O. Box 33 Maroua The hard rock-aquifer system in the urban context of Ngaoundere was investigated using piezometric measurements and hydro-chemistry to enhance understanding of its functioning and assess groundwater suitability for drinking and domestic purposes. Seasonal and intra-seasonal piezometric monitoring was conducted in different localities, along with chemical analysis of thirty-five ground and surface water samples. The chemical composition was determined for major elements using ion chromatography, and water facies and mineralization processes were assessed using Piper and Gibbs diagrams. The water quality index (WQI) was calculated to evaluate groundwater suitability for human consumption. The findings revealed diverse piezometric behaviors depending on well/borehole geomorphological positions and seasons. Wells situated on hilltops exhibited high piezometric fluctuations, while those in valleys near rivers showed low fluctuations due to support from river water levels. Recharge occurred during the rainy season through direct infiltration from hilltops, with stream water levels influencing piezometric levels in surrounding wells and boreholes. The surface and ground waters exhibited low mineralization, characterized by calcium-magnesium bicarbonate and sodic-potassic bicarbonate facies. Water-rock interactions and dilution with rainwater were identified as the main processes controlling water mineralization. According to the WQI, all groundwater samples were classified as "excellent quality water" for human consumption. However, the microbiological quality of groundwater in and around Ngaoundere was influenced by human activities, making it unsuitable for drinking without treatment. https://pubs.sciepub.com/ajwr/12/2/2/ajwr-12-2-2.pdf hard-rock aquifer hydrodynamic water-mineralization water-quality Ngaoundere