Exploring the Normalized Difference Vegetation Index for Desertification Risk Mapping in Gombe State, Nigeria

Abstract

Desertification poses a growing environmental threat in Gombe State due to its ecological vulnerability and geographical proximity to the most affected areas. However, the interplay between natural and human factors has aggravated the susceptibility of the region to land degradation. Therefore, this study aimed to assess the extent and progression of desert encroachment in the Gombe State by analyzing vegetation cover between 2001 – 2022 using satellite-derived vegetation indices. The study employed a Moderate Resolution Imaging Spectroradiometer (MODIS) derived Normalized Difference Vegetation Index (NDVI) process and analyzed in ArcGIS. NDVI maps for 2001 and 2022 were classified using a standard threshold to determine vegetation conditions in the study area. Transition analysis was conducted to detect changes in vegetation class over time and determine stability, degradation, or potential recovery. The result revealed a consistent decline in vegetation health and density over the study period, with average NDVI values decreasing from 0.36 in 2001 to 0.32 in 2022. Areas with no vegetation slightly increased from 1.2% to 1.4%. While sparse vegetation expanded significantly from 95.7% to 98.1%. Conversely, areas with vegetation only declined from 3.1% to 0.5%. Approximately, 95.3% of the study area remained persistently under sparse vegetation throughout the study. It has been concluded that the findings indicated an increasing risk of desertification in the study area which is anticipated to further impact environment and socio-economic activities. The study recommends the need for integrated and sustained mitigation and restoration strategies to combat further degradation and enhance the ecological resilience of the study area.