An integrated lineament extraction from satellite imagery and gravity anomaly maps for groundwater exploration in the Gongola Basin

Abstract

Structural trends in the earth's crust can be detected in the form of lineaments and may be useful in several environmental applications such as mineral exploration and hydrogeology. In this study, structural lineaments in the western sector of the Gongola Basin of northern Nigeria were mapped using two approaches - the analysis of gravity data and the processing of Landsat 8 imagery. In the analysis of gravity data, a convolution was done between the fourier kernel obtained from the second horizontal derivative of the truncated horizontal plate and the gravity anomaly. The lineaments were extracted as the sharp gradients in the second horizontal derivative map. The NE-SW and E-W trending lineaments were interpreted as fault (strike-slip wrench) systems. In the second approach, a 5 × 5 directional filter was applied to the Landsat imagery in the N–S, NE-SW, E-W and NW-SE directions. Next, edge detection, thresholding and curve detection were done to extract the lineaments. It was observed that the NW-SE and NE-SW lineaments correlated more with the lineaments/faults in the gravity maps. Comparison of rose diagrams of lineaments as obtained from the remote sensing method shows a high correlation with the major linear structures in the study area. High correlation exists between lineaments delineated from remote sensing and gravity data. Results from the lineament analysis show that groundwater potential is high in the areas with high lineament density. Settlements such as Mallurin Tudu Yautare, Wuro Bundu, Kunde and Tauya which are located in the northern part of the basin have high groundwater potential due to the high lineament density observed from the gravity and the remote sensing methods. Lafiya and Jimbom communities located in the south eastern part of the basin also have high lineament density which signifies good groundwater potential. These results have demonstrated the advantage of remote sensing for detecting lineaments in support of groundwater mapping. This good correlation between lineaments mapped from both methods strengthens existing studies on the structural manifestation of the Gongola Basin. This can serve as a reconnaissance approach to aid more precise geophysical observations.