Hydrogeological deep percolation modelling of groundwater recharge in Voinjama Region, Liberia

Abstract

Indirect physical methods of assess groundwater recharge rely on the measurement or estimation of soil physical parameters, which along with soil physical principles; can be used to estimate the potential or actual recharge. However, the deep percolation method uses a daily water- budget approach to simulate deep percolation. In this method, the model computes daily fluxes of water into and out of a volume extending from the top of foliage to the bottom of the root zone and accounts for changes in water content. In most environments, deep percolation is destined to recharge the saturated systems that are tapped by wells. Deep percolation technique was deployed to determine the rate of ground water recharge in the Voinjama region of Liberia, and also establish points of lineaments where wells can be dug for water supply. The perimeter of the hypothesized basin is about 28.9km while the length of the thalweg of the mainstream is about 11km. the average width of the basin area is 5.9km while the circumference of the equivalent circular area is 25.33km and compactness coefficient (R) of the basin is computed at 1.14. The elongation ratio (Er) is computed at 0.73km. The diurnal recharge computed from Deep Percolation was 6712.21 cm3 /km2 per annum. In conclusion, this study aids the restoration of water supply system destroyed during the war periods emphasizing the abundant water in the hydrological system and viable ground water recharge adequate for exploitation in a near uniform geology. Several faults and crevices scattered abroad the area were recorded indicating good lineament distribution and abundant aquifer recharge.Keywords: Hydrogeology, Deep Percolation Method, Groundwater, Recharge