Characterising Land Cover Changes in the Niger Delta Caused by Oil ProductionTools Kuta, A.A. (2023) Characterising Land Cover Changes in the Niger Delta Caused by Oil Production. PhD thesis, University of Nottingham.
AbstractIn recent decades, oil extraction activities have particularly affected land cover in the Niger Delta region, subsequently increasing or reducing the extent of certain land cover types. Where complete change has not occurred, the quality of the land cover may have still been affected and degraded. However, the extent to which oil activities have affected the landscape is not fully understood. This thesis presents an integrated multiscale land cover change characterisation using geospatial analyses to determine the impact of oil extraction activities on the land cover. Firstly, a spatiotemporal hotspot analysis of oil spills from 2007-2019 and oil facilities shows that the area around Omuko-Ahoada in the north-eastern and around Ijaw-South in the southern part of the study area are the most impacted by the oil extraction activities. Secondly, from analysis of the impact of soil hydrocarbon parameters (SHP) on the health of different types of vegetation at the leaf scale from field spectrometer data, the mangrove is the most impacted by total petroleum hydrocarbon (TPH) and soil toxicity by showing a decrease in chlorophyll content and low spectral reflectance. At the same time, the mango shows the most tolerance to TPH, while oil palm is the most tolerant to toxicity (EC50). Thirdly, from the analysis of the impact of the oil spill volume and time gap after the occurrence of oil spills on the health of dense, sparse and mangrove vegetation even many years after the occurrence of spills by way of normalised difference vegetation index (NDVI) show that the dense vegetation is only impacted at volumes 1000 barrels and sparse vegetation between 400 and 1000 barrels. However, the mangrove vegetation is not impacted at any volume. Additionally, the impact of oil spills was more visible within 90 days of the spill for sparse and mangrove vegetation than for dense vegetation, which can withstand the oil spill due to its size. Also, the result shows that the health condition of vegetation on spill sites is impacted by oil spills when compared with those on none spill sites for all vegetation types. Finally, land cover change detection at the landscape scale was performed using a Bayesian classifier from 1987-2016 and NDVI map. The results show that the oil extraction activities have affected the land cover, especially the vegetation, with many conversions from vegetation to non-vegetation and degradation occurring near oil extraction activities. The results from this thesis could help address the environmental problems in the Niger Delta, such as land pollution, degradation and land cover change, by prioritising programs such as oil spill cleans up or remediation and the restoration of the vegetation using some plants that have shown some resistance to the impact oil spills to ensure the sustainability of the natural environment in the Niger Delta.
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