Vulnerability and pollution of groundwater in Kisauni, Mombasa, Kenya

ABSTRACT: Rapid urbanisation in the Mombasa District, and in particular the Kisauni area, has increased the demand for essential services, notably water supply and waste management infrastructure. This is manifested in inadequate clean drinking water from the reticulated supply, leaving the inhabitants with groundwater to supplement their resources, or in most cases as the sole option. An assessment of the intrinsic aquifer vulnerability to contamination was carried out by applying the DRASTIC model coupled with GIS analytical tools. Monitoring data on physico-chemical characteristics showed raised concentrations of nitrates in groundwater, in particular, in the more densely populated Kisauni areas, attributed to contamination from on-site sanitation systems dominated by pit latrines and septic tank-soak pit systems and uncollected municipal refuse. Concentrations of NO31/NO2 1-N ranged from 0.4 to 44.4 mg l1, with an indication of seasonal variations.