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

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

Possible pathways of seawater intrusion along the Mount- Cameroon coastal area using remote sensing and GIS techniques

Coastal aquifers are vulnerable to salinisation due to seawater intrusion. Lineaments generally play the role of pathways for this intrusion. This paper investigates the lineament pattern in the region of southern-Cameroon with the main purpose of understanding the mechanism of the eventual contamination of groundwater by salinity. 472 lineaments are mapped in the study area using both Landsat-8 OLI and 7 ETM + images. 15 of those lineaments connect 19 contaminated boreholes to the shore. A total of 24 out of 58 boreholes are contaminated by seawater. A statistical analysis of this network depicts the responsibility of lineaments in seawater intrusion. Other aggravating factors are elevation (<100 m) and slope (<7°). A wide NE-SW-oriented fractured zone is detected within the flat area extending between Mount-Cameroon and Limbe-Mabeta Massif. Furthermore, several new fractured zones are highlighted, and will be considered when elaborating policy of local water management. This low-cost and time-saving approach which combines remote sensing and GIS has been effective, and recommended for similar investigations worldwide. A geophysical campaign with the purpose of characterizing local aquifer and upgrade hydrological, geological and electrical parameters of the local aquifer is scheduled