Analysis of future meteorological, hydrological, and agricultural drought characterization under climate change in Kessie watershed, Ethiopia

Abstract

The objective of this study is to analyze future drought characteristics in meteorological, hydrology, and agricultural droughts under the impact of changing climate in the Kessie watershed, upper Blue Nile Basin, using three drought indices; Reconnaissance Drought Index (RDI), Streamflow Drought Index (SDI) and Agricultural Standardized Precipitation Index (aSPI), respectively. The study used baseline data (1985–2014) and future (2041–2100) downscaled from Coupled Model Intercomparison Project 6 (CMIP-6) based on the three Global Climate Models (GCMs) projections under two scenarios of the Shared Socioeconomic Pathways (SSP) (SSP2-4.5, SSP5-8.5) with well-calibrated Soil and Water Assessment Tool (SWAT) model to simulate future streamflow for two future time horizons 2050s (2041–2070) and 2080s (2071–2100). Based on the yearly time scale, our results indicate that droughts of a high magnitude and rising frequency would affect most of the research area. These droughts will be either meteorological (RDI), agricultural (aSPI), or hydrological (SDI). Short-term agricultural and hydrological droughts are also anticipated to occur more frequently. The projected increases in frequency and trend of agricultural and hydrological droughts in this area are greater due to the anticipated drop in annual rainfall and the larger increase in mean annual temperature in the middle of Kessie. Furthermore, compared to hydrological and agricultural droughts, meteorological drought is less vulnerable to climate change; but, as the accumulation period lengthens, a stronger association develops between hydrological and agricultural droughts. These findings may be useful for water resources management and future planning for mitigation and adaptation to the climate change impact in the study area.