Mapping and Analysis of Vegetation Spectral Reflectance in Oil and Gas Seepage Polluted Zones Using Six Vegetation Indices

Chukwudi Andy Okereke ,Pius C Anyadiegwu

doi:10.7176/jees/9-7-05

Abstract

The growth and health of vegetation may be adversely influenced by oil and gas pollution or leakage. Thus, when an environment is contaminated with oil and gas pollution, growing vegetation often exhibit signs of stress. Satellite remote sensing has proven to be an effective tool and approach to detect and monitor vegetation health and status in oil and gas polluted zones. Previous studies have adopted vegetation indices which are obtained from remotely sensed satellite data to monitor vegetation health. This study is aimed at demonstrating the potential of vegetation spectral techniques for detecting and monitoring of oil and gas pollution from Landsat 8 OLI/TIRS remotely sensed data. To determine the influence of oil and gas pollution on vegetation reflectance, few polluted sites were analyzed and their reflectance were compared in all the TM bands against the non – polluted sites. The mean and standard deviation reflectance of each of the bands in two groups of sites and t – test are calculated to determine if there are any significant differences between the reflectance from the polluted and non – polluted sites. Thus, the study shows that in all the spectral bands, the vegetation reflectance from polluted and non – polluted areas exhibit small significant difference with a p-value >0.005. To further analyze the impacts of oil and gas on vegetation, six spectral indices including NDVI, SRI, MSAVI2, SAVI, ARVI2 and EVI2 were utilized. SRI, SAVI and EVI2 showed no significant relationship between polluted and non-polluted areas with a p-value > 0.05 higher than the alpha level of 0.05 and the calculated t - test value is lower than the t-critical value of 2.09 while NDVI, MSAVI2 and ARVI2 showed a significant relationship between the polluted and non-polluted areas. Keywords: oil and gas pollution, Ground Truthing, Vegetation Indices, Landsat 8 OLI/TIRS, Remote Sensing and Vegetation Cover. DOI : 10.7176/JEES/9-7-05 Publication date :July 31 st 2019

Highlights

Underground hydrocarbon reservoir often leak as a result of abundance of oil and gas at the earth’s subsurface and as the pass through impermeable seals, along faults zones, and fractures in rocks and planes of weakness between geological layers at high pressure
Adoption of vegetation indices minimizes the noise in the data
We need to first analyze if there were any significant differences between the vegetation indices derived for the polluted sites and those from the non-polluted sites

Summary

Introduction

Underground hydrocarbon reservoir often leak as a result of abundance of oil and gas at the earth’s subsurface and as the pass through impermeable seals, along faults zones, and fractures in rocks and planes of weakness between geological layers at high pressure. They form seepages at the earth’s surface. The negative impact of hydrocarbon seepages in our environment includes destruction of wild life, loss of fertile soil, pollution of air and water and damage to the ecosystem (Aghalino, 2000). Hydrocarbon seepage is one of the world’s environmental problems, which comes with negative impact on soil and vegetation. Hydrocarbon seepage affects the health status of vegetation and make them to be stressed

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