An appraisal of the usefulness of LandSat5_TM imageries in groundwater reconnaissance studies in Zaria – Kaduna area, north central Nigeria

Abstract

In order to assess the usefulness of remote sensing to groundwater resources studies especially with regard to the location of aquifers in the hard rock terrain, Landsat5_TM imageries were used in the Zaria – Kaduna area. In that area some information on the groundwater and the aquifers were already available. Image interpretation was carried out in two parts. In the first part, a structural interpretation was done by marking lineaments (fractures), from which their density (length/km2) per cell of 2.5 km x 2.5 km was calculated for the entire area. On the basis of the various values within the cells, a symbology of relative abundance of fractures in the area was created using classes to show the spatial distribution of areas where the fracture aquifer is likely to be encountered. The second part of the interpretation involved a spectral analysis and this was carried out employing the tasseled cap transformation. From the spectral analysis areas likely to produce good yields of water from the regolith aquifer were identified using interpretation keys. From the analysis of the fracture density areas that are favourable for the accumulation of groundwater in fracture aquifer were identified. Similarly, the relative variation of depth to the water table inferred from the spectral analysis was used to deduce areas that are favourably disposed to yield groundwater from the regolith aquifer. The surface information obtained from both the structural and the spectral analyses can serve useful reconnaissance purposes.

KEY WORDS: Groundwater, basement rocks, Landsat5_TM, fracture aquifer, regolith aquifer, Nigeria