Geospatial assessment of vegetation status in Sagbama oilfield environment in the Niger Delta region, Nigeria

Abstract

Forest ecosystems, species habitats and vegetation resources in Sagbama oilfield axis of the Niger Delta ecological zone are disproportionately stressed out by increased oil and gas industrial activities and are rapidly degrading. This study aims to achieve a conservation-driven assessment of vegetation dynamics under such human-induced disturbances, as a strategy for informing the natural resources sector policy formulation. A 26-years change detection starting from 1987 to 2013 was performed on Landsats 4TM, 7ETM and 8 OLI/TIRS datasets at 30 m resolution. The Normalized Difference Vegetation Index (NDVI) and the Maximum Likelihood Classifier (MLC) supervised methods of geospatial techniques in Remote Sensing and Geographic Information System (GIS) were applied on these datasets. Results indicates severe decline of healthy forests and vegetation resources as revealed by 0.23 deviation in NDVI of 0.55 (41.98%) in 1987 to 0.32 (24.43%) in 2002. Nonetheless, in 2013, a 15.76% vegetation gain was registered given an NDVI value of 0.44 (33.59%), yet, falls below the initial NDVI threshold of 0.55. Thereby, implying that rates of forest and vegetation recovery are much slower compared to rates of degradation. However, this study provides baseline statistics and other helpful information for the effective management of vegetation and natural resources in the coming years.

Keywords

• Vegetation degradation
• NDVI
• Image classification
• Niger Delta region of Nigeria