Comparison of CMIP5 models for drought predictions and trend analysis over Mojo catchment, Awash Basin, Ethiopia

Abstract

Climate change's effects on water, such as floods, droughts, ocean acidification, and increasing sea levels, are expected to worsen in the future years. In the context of the development the subject of mitigating the anticipated effects of drought has become highly important. Droughts in the African mainland are immediately in danger of hunger, particularly in Ethiopia. The creation of Global Climate Models (GCMs) and analysis of impending catastrophic events are two of the finest ways to handle this issue. This study analyzes the future Meteorological and Hydrological Drought with a comparison of GCM models on the Mojo Catchment using the Standardized Precipitation Index (SPI), Reconnaissance Drought Index (RDI), and Streamflow Drought Index (SDI) methodologies, under three slice periods at near (2006-2030), mid (2031-2055) and far (2056-2080) under the Representative Concentration Pathways (RCPs) including RCP4.5 and RCP8.5 scenario data. Overall Meteorological drought results show that at yearly time scale drought incidence is lower than biannual time scale in both indices. MIROC-MIROC5 and MPI-M-MPI-ESM-LR models are conducted for drought analysis. Under SPI6 (biannual period), 22% of the highest drought observed at far future periods at a scenario of RCP4.5 and for time scale SPI12 the frequency of drought decreases. On the catchment, there is no significant trend increase but both the meteorological and hydrological drought indices show the catchment to be highly susceptible to moderate range of drought and then severely drought takes place. Model MPI-M-MPI-ESM-LR is the most significant contributor to the analysis of the size and frequency of droughts and station Ejere is more venerable to drought as compared with other stations under the MPI-M-MPI-ESM-LR model. The occurrence of SDI12 drought on the MPI-M-MPI-ESM-LR model has a direct relation with the anomaly's climate variables (temperature and Precipitation). the maximum driest drought variability occurred at the same GCM model (anomalies up to -3.7mm) in the year 2041. Additionally, the frequency occurrence of drought at the annual timescale (SDI12) under RCP8.5 at the far future period of the catchment is suspected to 22% probability of drought occurrence. Overall, the Mojo catchment is moderately vulnerable to drought, and SPI-6 is more suspected to high frequency on drought under RCP4.5 especially near and mid periods. It is crucial for an organization, individuals, academics, water resource professionals, and disaster risk management in the catchment on alerting and planning water projects.