Groundwater Quality Analyses along Kenyan Coastal Region, Case Study of Kilifi-Kenya

Abstract

The Kenyan coast is a semi-arid region frequently faced with severe water scarcity especially during prolonged drought and a rapid population growth. Groundwater provides 50% of the water demand and most sources are poorly drilled, over-abstracted and abandoned. The aquifers occur in sedimentary formations of fluvial and lacustrine origin. There is a need to have a groundwater monitoring system in place; therefore this study analyses selected physico- chemical and microbial parameters using both laboratory and field methods. Arc-GIS 9.3, SURFER were used to generate thematic maps for some tested parameters. Results indicate pH values within acceptable range of 6.5 – 8.5, though shallow wells in Malindi were acidic, this atrributed to the heavy industries prevalent in the area. Electric conductivity (EC) was above the set standard of 1500μS/m indicating high dissolved ions present especially in Magarini where salt mining is done. Total dissolved solids (TDS) of up to 500mg/L suitable for drinking water was only found during the wet season. Turbidity of less than 5 NTU was established in most areas. Chlorides and salinity levels exceeded 250mg/L pointing to the saltwater intrusion problem that is a challenge along Kenyan coastal aquifers Boreholes and shallow wells had a total hardness ranging from 50mg/L -150mg/L indicating the water was ranging from being slightly hard to hard water. Escheriria coli was present in almost all the boreholes and shallow wells indicating the need to treat water before use. Water Quality index (WQI) calculation indicate that groundwater is unsuitable for human consumption in dry season.