The impacts of climate change on hydrological processes of Gilgel Gibe catchment, southwest Ethiopia

Abstract

Climate change is a significant driver of water resource availability, affecting the magnitude of surface runoff, aquifer recharge, and river flows. This study investigated the impact of climate change on hydrological processes within the Gilgel Gibe catchment and aimed to determine the level of exposure of water resources to these changes, which is essential for future adaptability planning. To achieve this objective, an ensemble mean of six regional climate models (RCMs) from the coordinated regional climate downscaling experiment (CORDEX)-Africa was used to simulate future climatic scenarios. The RCMs outputs were then bias corrected using distribution mapping to match observed precipitation and temperature. The Soil and Water Assessment Tool (SWAT) model was used to assess the hydrological impacts of climate change on the catchment. The results indicated that the ensemble mean of the six RCMs projects a decline in precipitation and an increase in temperature under both the RCP4.5 and RCP8.5 representative concentration pathways. Moreover, the increases in both maximum and minimum temperatures are higher for higher emission scenarios, indicating that RCP8.5 is warmer than RCP4.5. The projected climate change shows a decrease in surface runoff, groundwater, and water yield, resulting in an overall decline of annual flow. This decline is mainly due to the reduction in seasonal flows driven by climate change scenarios. The changes in precipitation range from -11.2% to -14.3% under RCP4.5 and from -9.2% to -10.0% under RCP8.5, while the changes in temperature range from 1.7°C to 2.5°C under RCP4.5 and from 1.8°C to 3.6°C under RCP8.5. These changes could lead to reduced water availability for crop production, which could be a chronic issue for subsistence agriculture. Additionally, the reduction of surface water and groundwater could further exacerbate water stress in the downstream areas, affecting the availability of water resources in the catchment. Furthermore, the increasing demands for water, driven by population growth and socioeconomic progress, along with the variability in temperature and evaporation demands, will amplify prolonged water scarcity. Therefore, robust climate-resilient water management policies are indispensable to manage these risks. In conclusion, this study highlights the importance of considering the impact of climate change on hydrological processes and the need for proactive adaptation measures to mitigate the impacts of climate change on water resources.

Impact of Climate Change on the Water Balance of the Akaki Catchment

“…Scholars worldwide have employed bias correction approaches to address precipitation biases in simulated datasets. Based on the acceptable performance of Distributed Mapping mentioned in [33,[55][56][57], we applied this method to the extraction and bias correction of rainfall and temperature. Figure 4 depicted the overall methodologies applied in this paper.…”

The Ripple Effect of Climate Change: Assessing the Impacts on Water Quality and Hydrology in Addis Ababa City (Akaki Catchment)

“…Climate change is among the primary issues in sustainable water management [ 1 ]. According to studies and models of climate change at the global and regional scales, temperatures are rising, while precipitation is dropping and becoming more erratic and unpredictable [ 2 , 3 ]. Climate change impacts water resources mainly through interception of the catchment hydrologic processes [ 4 ].…”

GIS-based spatio-temporal analysis of rainfall trends under climate change in different agro-ecological zones of Wolaita zone, south Ethiopia

“…This fluctuation endangers water provision and triggers an assortment of hydrological and meteorological disasters. Meanwhile, the country's diversified topography and demographic diversity further complicate coping and relief efforts for a population reliant on existing natural assets [ 9 , 13 ]. Going forward, bolstering resilience at the community level through collaborative projects and capacity-building will prove pivotal in enduring contemporary environmental unpredictability and safeguarding livelihoods [ 14 ].…”