Spatial Analysis for Surface Water Quality Assessment of the Ikpoba River Using Geographic Information System

Abstract

The aim of this study is to assess the water quality of the surface water body in the study area (Ikpoba River) in Benin City using the Geographic Information System (GIS). The present research involved the spatial analysis of water quality for four stations along the Ikpoba River in Benin City. The four stations were delineated using satellite images of Google Earth. At the same time, water samples were collected at these stations and the parameters such as Temperature, Turbidity, pH, Total Dissolved solids (TDS), Total Suspended Solids (TSS), Dissolved Oxygen (DO), COD, Biochemical BOD, Electrical Conductivity (EC), Zn, Cl, NH4N, Ca, Pb, SO4, Fe, Mg, NO3, PO4, and Total Hardness were analyzed in the laboratory. The analytical result of water samples was compared with WHO (World Health Organization) maximum permissible limits for the parameters tested and it was found that DO, TDS, EC, pH, NH4N, Zn, Ca, Mg, NO3, and Cl all fell below the WHO standard at all four points along the Ikpoba river. Inverse Distance Weighted (IDW) was employed for the spatial analysis using ArcGIS software. The database for all spatial data was created using GIS interpolation according to the IDW method to obtain the spatial distribution of each selected water quality parameter. It was estimated and concluded that the quality of water from the four different stations on the river varies comparatively with the permissible limits given by WHO Standards, with only a few parameters falling below the acceptable limit and the spatial extent of water quality is changing with respect to the parameter and its values.