Monitoring rainfall and drought trends using remote sensing-derived climate and vegetation indices in semi-arid eco-zone, Nigeria

Along with flooding and wildfire, Drought is a major natural hazard that continues to ravage the environment in many parts of the world, causing widespread social and economic devastation as evidence of climate change. This study aimed to assess the spatiotemporal pattern of drought events across Sudano-Sahelian Ecological Zone of Nigeria. This analyzed the daily accumulated precipitation and temperature from seven (7) weather stations in the study. Although scientists have relied on data obtained from meteorological stations. However, meteorological data are mostly scarce, expensive and sparsely distributed, especially in developing countries. This research was conducted using (CHIRPS) datasets from 1987-2022 to calculate SPEI and the SVI derived from MODIS using the Google Earth Engine cloud platform. The spatial and temporal variation of vegetation conditions in the Sudano-Sahelian region of Nigeria were examined using SVI. The results showed mild drought events at some parts of the study area, but there were severe to extreme drought events at Maiduguri station experiencing extreme drought in 2012, severe drought in 2004, 2005 and 1990, and moderately dry conditions in most years. Extremely wet conditions in 2012 and very wet conditions in 1994, 1996, and 1989. Katsina station experienced drought extremes in 2022, 2010, and 2005 while in Kano station, extreme drought was notably recorded in 2004 and 2006 (SPEI > -2). The findings show that drought affects the vegetation health and agricultural activities in the study area (SVI -3.7). The result of the study is important for policy decisions, water resources management in the face of increasing drought risks in the semi-arid region of Nigeria providing evidence-based insights for the development of early warning systems and strategic communication frameworks to mitigate the socio-economic impacts of droughts in vulnerable communities.