# Remote Monitoring of the Impact of Oil Spills on Vegetation in the Niger Delta, Nigeria
## 4 Conclusions  
This study utilised Landsat satellite-derived NDVI to determine the impact of oil spills on dense, sparse, and mangrove vegetation in the Niger Delta region using linear regression to determine the impact of oil spill volume and the time gap after an oil on the health of the vegetation, and, secondly, used Pared \(t\)-test determines the difference between the health of the vegetation exposed to an oil spill and the vegetation not exposed to the oil spill. The major findings are as follows:  
* The mangrove and sparse vegetation are the most degraded vegetation in the Niger Delta, and the sparse vegetation is the most affected among the three vegetation types by oil spills between 401 and 1000 bbl, whilst the dense vegetation responds more at a higher volume >1000 bbl. * The effect of the time gap after a spill is not statistically significant for all the vegetation types. * There is a statistically significant difference in the health condition of vegetation affected by oil spills compared to the vegetation unaffected by the oil spill. Despite the lack of a statistically significant relationship between the oil spill volume and time gap for most volume ranges, there is clear evidence that the health of vegetation in the Niger Delta is degraded when it is exposed to oil spills for all vegetation types. However, the result shows a statistically significant difference between spill sites and non-spill over time for all vegetation types. This has provided insight into how different types of vegetation respond to an oil spill, which could help in designing an oil spill clean-up program to reduce the impact of oil spills on different types of vegetation in the Niger Delta by prioritising oil spill clean-up based on the vegetation type that is most affected by the impact of the oil spill. The implication of the results is that the oil spill volume should not be the sole requirement when responding to or mitigating the impact of the oil  
Figure 15: Temporal changes in NDVI (\(\Delta\)NDVI) at spill sites (SSs) for different oil spill volumes in (**a**) dense vegetation, (**b**) sparse vegetation, and (**c**) mangroves. spill on vegetation. Each site should be treated differently based on other factors such as the soil type, topography, etc. The long-term impact of oil spills on the vegetation could be mitigated by designing an early oil spill detection and clean-up response program to ensure that such vegetation recovers within the shortest period. The use of satellite-based-derived NDVI provides a unique option to monitor the health of vegetation in places like the Niger Delta. It provides spatiotemporal data without the need to visit the site due to security concerns. However, further research is recommended for the mangrove to investigate the lack of correlation between the oil spill and the NDVI value through ground visits and analysis of the leaf sample to determine if the mangrove has developed some form of resistance to the oil spill's impact due to constant exposure. Future work is being undertaken to understand vegetation impacts using leaf samples. In addition, other nonlinear regression analyses may be used since regression may not fully reveal a nonlinear relationship. Conceptualization, A.A.K. ; methodology, A.A.K., S.G., and D.S.B. ; software, A.A.K. ; validation, A.A.K., S.G., and D.S.B. ; formal analysis, A.A.K. ; investigation, A.A.K. ; resources, A.A.K., S.G., and D.S.B. ; data curation, A.A.K. ; writing--original draft preparation, A.A.K. ; writing--review and editing, A.A.K., S.G., and D.S.B. ; visualization, A.A.K. ; supervision, S.G. and D.S.B. ; project administration, A.A.K. ; funding acquisition, A.A.K. All authors have read and agreed to the published version of the manuscript. This research was funded by the Petroleum Technology Development Fund (PTDF) under the Federal Government of Nigeria (PTDF/ED/PHD/KAA/966/16). Not applicable.