“Spatio-temporal characterization of Agricultural Drought using Soil Moisture Deficit Index (SMDI) in the Upper Tana River basin, Kenya” (2019) International Journal of Engineering Research and Advanced Technology (ijerat) (E-ISSN 2454-6135) DOI: 10.31695/IJERAT, 5(2), pp. 93–106. doi:10.31695/IJERAT.2019.3388.