Vulnerability assessment of drought over Borno State, Nigeria using geospatial technique

Nigeria is experiencing unfriendly climate condition which has a negative impact on the welfare of millions of people. The need to assess the vulnerability of drought across areas in Nigeria, especially in the Sudan and Sahel region is timely. This study investigated the effectiveness of remote sensing-based drought assessment, examined the relations between rainfall and vegetation indices and identified the most drought vulnerable areas using remote sensing (RS) and GIS in Borno State. Landsat images of years 2010, 2015 and 2020 were downloaded from USGS site. Geometric and atmospheric corrections were performed to adjust the terrain displacement and improve the reflective properties of the image data. Normalized Difference Vegetation Index (NDVI) and Normalized Condition Index (NCI) data were performed on the satellite images. Result of this study indicates NDVI, for the three epochs recorded; non-vegetation as 0.6%, 9.61% and 17.13%. Shrub/Grass was 96.6%, 82.50% and 78.34%, dense vegetation was 2.8%, 9.4% and 4.53%. The drought analyses of (NCI) recorded the following; extreme drought 2.3%, 6.06%, 9.99%, severe drought; 2.52%, 13.54%, 28.5%, Moderate drought: 69.1%, 52.6%, 41.64%, No drought: 4.34%, 3.44%, 3.34% while wet drought: 21.7%, 24.4% and 18.43%. At 95% significance level, the extreme drought indicates an increase trend pattern of about 1.8%, the moderate drought indicates a decreasing trend pattern about 9.4% while the severe drought indicated an increasing trend of about 5.3%. Climate parameters (Rainfall and temperature) were used to validate the outcome of NDVI and NCI. The findings indicated that the study area is highly prone to drought, which has affected the agricultural sector and land conservation of the state. Hence, the authority responsible for the state environment management should put in place strategies that can enhance water efficiency, improve resilience and reduce drought vulnerability.