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Öğe Evaluation of groundwater vulnerability using GIS-based DRASTIC model in Greater Monrovia, Montserrado County, Liberia(Elsevier, 2023) Koon, Arthur B.; Anornu, Geophrey Kwame; Dekongmen, Benjamin Wullobayi; Sunkari, Emmanuel Daanoba; Agyare, Asante; Gyamfi, CharlesTo ensure that groundwater resources are effectively protected and to improve the quality of life, it is vital to take into consideration all polluting activities that could pose a potential risk to the resource. Groundwater potential research conducted only covers 5% of Montserrado County excluding Greater Monrovia in Liberia. Although this little percentage of groundwater potential research is well known, studies on the vulnerability of the aquifer to pollution are non-existent. Therefore, this study aims at assessing groundwater vulnerability in Greater Monrovia, Mon-tserrado County, Liberia, which will help in optimizing water well drilling activities and pro-tecting the resource. A groundwater vulnerability map for the study area using the Geographic Information System (GIS) based DRASTIC Model was developed and the results suggest that 73% of the study area is very sensitive to pollution, whereas 15% and 11% are moderately and weakly sensitive to pollution, respectively. The key pollution areas identified within the study area were communities of intensive anthropogenic activities and associated geological contamination. The effectiveness of the GIS-based DRASTIC Model in groundwater vulnerability assessment was validated and nearly 60% of the wells contained fluoride concentrations that exceeded the Liberia Water Quality Standard (LWQS) permissible limit. The findings suggest that even though the water table is relatively shallow, future projects in the high and moderate sensitivity zones should be handled carefully. Planners, groundwater managers, and decision-makers may utilize the maps created by this study as a general point of reference for vulnerability when making attempts to safeguard this delicate resource.Öğe Groundwater recharge estimation and potential recharge mapping in the Afram Plains of Ghana using SWAT and remote sensing techniques(Elsevier, 2022) Dekongmen, Benjamin Wullobayi; Anornu, Geophrey Kwame; Kabo-Bah, Amos Tiereyangn; Larbi, Isaac; Sunkari, Emmanuel Daanoba; Dile, Yihun Taddele; Agyare, AsanteThe Afram Plains watershed is one of the major watersheds located at the lower part of the Volta Basin in Ghana with high groundwater usage. Dependency on groundwater is a fast-growing concern in the plains due to the unreliable supply of surface water. This has put the groundwater resources under intense pressure and has necessitated the need for sustainable management of the groundwater resources. This study aimed to estimate the recharge, spatial distribution, and potential recharge zones of groundwater at different scales in the Afram Plains area using the Soil and Water Assessment Tool (SWAT) model and Geography Information System (GIS) approach. The SWAT model was set up (1983-2016), calibrated (1983-1990) and validated (1991-1997) using digital elevation model, soil, land use, climate datasets, and discharge data. The GIS approach was used to produce thematic maps for eight contributing factors; rainfall, elevation, land cover land use, lineaments, drainage, geology, soil and slope for mapping the recharge zones. The results showed that about 1.65% (19.3 mm) of the SWAT simulated mean annual rainfall (1176.9 mm) is converted into groundwater recharge in the watershed. The potential recharge zones categorized as very poor, poor, moderate and high zones have area coverages of 0.58% (20.8 km(2)), 22.4% (798 km(2)), 60.9% (2169 km(2)), and 16.2% (576 km(2)), respectively. The potential recharge zones after validation over boreholes and wells data indicated that the Afram Plains area is dominated by the moderate potential zone.