GROUNDWATER QUALITY AND WATER RESOURCE ASSESSMENT OF THE KINGSTON BASIN, JAMAICA

Groundwater is the dominant source of potable water supply for Jamaica, the Small Island State of the Caribbean. Sustainable management of groundwater resources requires monitoring its water quality, resource assessment and demand and supply management. Climate change has affected the water resources in the island with the Kingston hydrological basin being affected due to its high population density, limited groundwater resources and poor sewage management. The Kingston basin has two major aquifers ie limestone and alluvium. Variability in the rainfall pattern coupled with contamination of the alluvium aquifer effectuated the closure of majority of the groundwater wells and a heavy reliance upon surface water systems. This thus, creates an increase in demand for potable water from limited surface water resources and water shortage during periods of drought within the KHB and adjoining basins. The current water quality of the groundwater system in the KHB was assessed with monthly monitoring during 2018-2019 from 13 available wells representing the limestone and alluvium aquifers. The samples were analysed for NH4 + , NO3¯, PO4 3- , SO4 2- , Cl¯, Mg2 ⁺, Ca2 ⁺, Na⁺ and K⁺. Spatial and temporal variation of the nutrients were investigated. The limestone aquifer displayed lower concentrations of the tested nutrients than the alluvium aquifer. Higher levels of NO3¯ and Cl¯ were observed in the coastal wells’ samples of the alluvium aquifer, located in proximity to industrial and densely populated areas implying sewage influx and saline intrusion as sources. Major ion ratio plots suggested geogenic and anthropogenic sources of the contaminants. Analyses of the hydrochemical facies using the Piper and Durov diagrams showed both aquifers consisting of earth alkaline water, predominantly of bicarbonates and sulphate type.