Spatio-temporal characterization of Agricultural Drought using Soil Moisture Deficit Index (SMDI) in the Upper Tana River basin, Kenya

Occurrence of Agricultural drought in a river basin is associated with food insecurity. There is need to integrate agricultural drought characteristics in decision making within upper Tana River basin. In this research, characterization of spatio-temporal Agricultural Drought using Soil Moisture Deficit Index (SMDI), based on hydro-meteorological data was conducted. Eight meteorological stations with data for 41 years were used. The computation was interpolated using kriging interpolation technique within ArcGIS environment. The long-term soil-water was simulated using AquaCrop model. For station ID 9037112, the values of SMDI for dry season are lower than those for the wet seasons. It is deduced that the lower elevations of the basin in southeastern parts exhibit more drought-prone areas than those in the higher elevations at north-western areas. From this study, Severity-area-frequency curves (SAF) curves for 2, 5, 10, 20, 50 and 100-year return periods were developed. The analysis of spatio-temporal drought characteristics can be adopted for prioritized mitigation of agricultural drought impacts.