Assessing agricultural and hydrological drought vulnerability in a savanna ecological zone of Sub-Saharan Africa

Despite measures to mitigate drought, study on the extent of agricultural and hydrological drought vulnerability is still neglected in the savanna ecological zone of Nigeria. This study assessed agricultural and hydrological drought vulnerability in Kaduna River Basin (KRB). To achieve this, monthly rainfall, temperature, and soil moisture data were downloaded from the climate hazards group infrared precipitation with station data (CHIRPS) and ERA5 Copernicus data archive. Streamflow data were obtained from ten hydrometeorological stations (1990–2018) while Landsat imageries 4, 5, 7, and 8 of 30 m resolutions were used to generate vegetation condition index (VCI), modified normalized difference water index (MNDWI), and landuse/landcover (LULC). The two drought types were assessed for 1990, 1997, 2004, 2011, and 2018. The result of high and moderate severity of VCI revealed upward trends of r2 = 0.3026 and r2 = 0.3779, respectively. Analysis showed that within ranges of 50 to 80% and 58 to 82% of the basin area were, respectively, mapped as moderate agricultural and hydrological drought hazards zones. The study reveals that most parts of the basin are moderately vulnerable to both agricultural and hydrological drought events at 62.15 and 72.44%, respectively, while high agricultural and hydrological drought vulnerability areas accounted for 18.29 and 17.42%, respectively.