ASSESSING THE IMPACT OF RAINFALL VARIABILITY ON VEGETATION COVER IN SOME PARTS OF YOBE STATE, NIGERIA

Abstract

This study aimed to assess the impact of temporal rainfall variability on vegetation cover in some part of Yobe State. By determining the temporal pattern of rainfall variability, the extent of vegetation cover, and the relationship between them. Rainfall variability is a significant concern in some part of Yobe State, with potential consequences for agriculture, forests, water resources, and human beings. The study employed a combination of statistical analysis, remote sensing, and GIS techniques, using rainfall and vegetation cover data from the Nguru meteorological station and the USGS Earth Explorer respectively for the period 1992–2022. NDVI, SAVI, and correlation analysis were used to determine the relationships between rainfall variability and vegetation cover. The result showed significant temporal rainfall variability, with an upward (increasing) trend over the study period. The coefficient of variation (CV) for annual rainfall was also employed to quantify the rainfall patterns. The CV of inter-annual variability (28.9%), indicating considerable and moderate variability in total rainfall received. Subsequently, the extent and changes in vegetation cover were found to be sparse, with a mix of forest, grassland, and agricultural land uses. However, an increasing trend in vegetation cover has been observed in recent years. The analysis of the NDVI reveals that vegetation cover has a promising upward trend from 1992 (3.24%) to 2022 (22.13%). Also, the SAVI indicates an upward trend in the vegetation cover. Building upon these individual analyses, the results reveal a positive correlation between periods of increased rainfall and vegetation cover. This study recommends the need for continued research and monitoring to better understand the complex relationships between rainfall variability and vegetation cover and to develop effective strategies for mitigating the impacts of climate change on ecosystems. Furthermore, there is a need to address the impacts of human activities, such as deforestation, overgrazing, and unsustainable agricultural practices, which exacerbate the degradation of vegetation cover.