Long-Term Monitoring of Oil Spill Impacted Vegetation in the Niger Delta Region of Nigeria: A Google Earth Engine Derived Vegetation Indices Approach

Abstract

New and emerging cases of oil spill incidents are reported almost on a weekly basis in the Niger Delta region of Nigeria with accusations and counter-accusations as to the claims made by interested parties on perceived impacts of the spills on the environment and its associated constituents. This study applied the capabilities offered by the Google Earth Engine (GEE) platform to monitor long-term vegetation dynamics as a result of exposure to pollution emanating from crude oil spills in the Niger Delta region of Nigeria. The capabilities offered by GEE provide a platform for rapid access to big data for the assessment of environmental change, especially in the Niger Delta with its difficult terrain and security concerns. This study considered oil spill incidents in vegetated terrestrial locations in the Niger Delta across ten years. Fifteen locations spread across the region with oil spill incidents identified as large incidents being selected (>50 <5000bbl). Results of the statistical analysis performed on the vegetation indices data generated from GEE suggest that the analysis of long-term vegetation indices using GEE can provide a broad view of the impact of oil spills on vegetation over time if the spills are relatively large or the spills are repetitive. However, when the spills were relatively small, there was no statistically significant variation in the spectral signatures of the vegetation over time. This suggests that for large spills, GEE-derived vegetation indices can be a very useful synoptic tool in monitoring oil spill occurrence and impact on vegetated terrestrial environments in the Niger Delta and elsewhere where environmental accessibility is a challenge.