Mapping Groundwater Quality Parameters Using Geographic Information System (GIS) in Oyo State, Nigeria

Abstract

The knowledge of spatial pattern of groundwater quality is important to ensure a holistic approach to the management of the resource quality status in space and time. Thus a sample each of underground water was collected from each of the selected 5 rural communities in each of the selected 25 out of the 33 LGAs in Oyo State for the purpose of quality assessments. Eleven (11) parameters namely water temperature (°C), pH, electrical conductivity (EC), Sodium (Na+), SO4, Potassium (K+), Nitrate (NO3), Phosphate (PO3), coli-form count, Oxidation Redox Potential (ORP) and Total Dissolved Solids (TDS) were subjected to standard laboratory analysis. The data was further subjected to analysis of variance and Duncan post-hoc test. ArcGIS version 10.1software was applied to generate maps to show the Duncan groupings of each of the quality parameters across the study area. Two (2) parameters namely pH and sulphate show homogenous distribution while the other nine (9) parameters are heterogeneous. Descriptive analysis showed that the groundwater in the study area is generally fit for human consumption. However, adequate attention needs to be given to temperature and potassium contents because they both slightly exceeded the standard required. The mapping affords spatial understanding of the distributional pattern of the parameters so that appropriate water quality management measure/s can be taken at a minimised cost to ensure appropriate levels of the parameter in the water to safeguard human health. Repeated investigation is required to determine the regularity or otherwise pattern of the water quality parameters.