GIS-Based Underground Water Quality Risk Mapping of Kaltungo L.G.A, Gombe State, Nigeria

The research aimed at identification and risk mapping of the concentration of physiochemical properties of some metal ions in the underground water in Kaltungo LGA of Gombe State with the aid of Geospatial Techniques. Water samples used comprises of all of the 40 wells and boreholes were sampled and two control points and out of that, wells constitute about 25 and 15 boreholes respectively. Also, ten metals ions which includes;  Alkalinity of the water, B.O.D, C.O.D, D.O, Chloride, Electric Conductivity, Fluoride,Nitrate, phosphate, Sulphate, T.Hard, were selected and analyzed in laboratory. DEM, Curvature, Watershed, Aspect, Slope and Hillshed were also used. The methods employed were both Laboratory and Geospatial techniques.  The result obtained from the lab was compared with WHO standards, imported in to ArcGIS 10.3 environment and interpolated and subsequent analysis were done using kringing methods and query. Based on the query from the geodatabase of the underground water, it was found that 60% out of the metal ions used in this study were not in conformity with the WHO standards for drinking water. Amongst these metals are; Electric Conductivity, Fluoride, Nitrate, Sulphate, T.Hard and T.Hard. It was also found that 97.5% of the wells and boreholes have higher concentration of Fluoride, 85% Sulphate, 75% Electric Conductivity and 55% Nitrate while 32.5% and 30% have lower concentration of T.Hard and Turbidity respectively. Again reveal that those metals with higher concentrations of physiochemical properties are found to be within lower elevation, moderately water table due to down slope movement of water.Moreover, it was revealed that due to the convex profile curvature and watershed nature of the study area physiochemical of the water was accelerating to the lower slope towards the Northeast and Eastern part of the study area. Furthermore, it was found from the risk map that the vulnerability underground water risk area was the Northeast, central and Eastern part of Kaltungo. It was recommended that GIS techniques should be of paramount used in examine water related issues so as the results will served as a basis for decision support for WHO and others related organizations