Geospatial and statistical interpretation of lineaments: salinity intrusion in the Kribi-Campo coastland of Cameroon

Abstract

This study detected, mapped and analysed lineaments from Landsat-8 satellite images of the coastal area of Kribi-Campo, Cameroon. Kribi, a fast-growing coastal city with a youthful population whose main industry is agriculture, is currently under great pressure due to the influx of internally displaced persons, victims of the current socio-political crisis in the western part of Cameroon. With the growing demand for food and water resources, it has been reported that saline soils and groundwater are affecting the agricultural productivity and domestic water supply of the area. This paper investigates the lineaments network in this area to understand its spatial distribution, its extent and the potential effect on inland intrusion of saline water. The datasets, including Landsat-8 imagery, geological data and a digital elevation model were processed using principal component analysis and filtering techniques. Linear features were enhanced based on textural changes of false colour composite images to describe fractures, faults and hydrology features. 390 effective lineaments were extracted automatically and manually from those images and analysed based on length, density and orientation using statistical analysis. But before this processing, non-effective lineaments that may correspond to terraces, linear valleys, cliffs, or tonal contrast as well as to human activities have been deleted. The effective lineaments range in length from 95 to 4910 m with an average of 1171 m. Although the lineaments are not isotropic, their perpendicular orientations to the coast suggest potential intrusion of saline water into regional groundwater resources and farmlands. The paper presents a combined technique of geospatial and statistical analysis in the interpretation of lineament effects which have the potential to inform on salinity intrusion in coastlands. The electrical conductivity of 50 groundwater samples collected in the study area are used to validate the impact of lineaments on seawater intrusion.