HYDROCLIMATIC TIME SERIES ANALYSIS AND MODELING OF THE UPPER AWASH RIVER SUB-BASIN UNDER CLIMATE CHANGE CONDITIONS, ETHIOPIA

Abstract

Studies of Hydro-climatic time series analysis and modeling are very crucial for planning and management, and utilization of water resources of the Upper Awash River basin, Ethiopia. This study aimed to evaluate hydroclimatic time series data and its modeling to assess the impact of climate change on streamflow in the Upper Awash River basin. The water balance components can be affected by climate change and need to be evaluated through analyzing the impacts climate change. The non-parametric Mann-Kendall trend test were adopted to detect and analyze trends in monthly, seasonal, and annual hydro climatic variables. The influence of climate change on stream flow was assessed using the Seasonal Autoregressive Integrated Moving Average with exogenous variables (SARIMAX) model and selected four GCMs namely CCCMA, CNRM, ICHEC-EC EARTH, and MPI with RCP4.5 and RCP8.5 scenarios. The GCM outputs for the base period (1976-2005), short-term (2021-2050), and long-term period (2051-2080) forced the calibrated and validated SARIMAX model. The calibration result showed that R2 is 0.95 and NSE is 0.81 were used, while for validation, an R2 is 0.99 and an NSE is 0.82. The results of all GCMs also indicated that in the short and long term, temperature and evapotranspiration will be increased under both RCP4.5 and RCP8.5 scenarios. The projected annual streamflow, and precipitation showed that in the short and long term, streamflow, and precipitation will be decreased under both the RCP4.5 and RCP8.5 scenarios. The study results can clearly reflect the overall situation of Climate change impact on streamflow under two climate scenarios, and provide basis for planning, management, and sustainable of water resources in the future.