Climate Change-Induced Hydroclimatic Extremes in the Drylands of Northern Ethiopia: Implications for Water Resources Management

Abstract

Climate change is increasingly impacting society and the environment around the world, with water-scarce regions such as dry lands being particularly vulnerable due to their limited resource availability. In East Africa, recent intensification of climate variability and change has worsened existing environmental challenges, including extreme rainfall events, floods, and frequent droughts. Ethiopia, is among the most susceptible areas to these changes, having endured some of the most severe droughts in recent decades. This shifting climate poses a significant threat to water resources, especially in northern Ethiopia, where persistent land degradation and frequent droughts—largely driven by fluctuating rainfall patterns have intensified the vulnerability of the region. The climate and hydrological systems of northern Ethiopia, especially in the Tigray region, are highly complex, influenced by diverse topography, and pronounced seasonal and spatial variability in rainfall, varied soil types, and dynamic land use changes. These factors, combined with variability in physiography, lithology, vegetation cover, and land management, lead to substantial differences in hydrological processes across basin or sub-basins such as in the Geba sub-basin, which is part of the headwaters of the Tekeze River. The sub-basin, exhibits pronounced inter annual rainfall variability, sparse vegetation, steep slopes, flood and recurring drought events. Addressing these issues demands a comprehensive understanding of climate variability and change, its impacts across multiple spatial and temporal scales to support resilient water resource development and management in this vulnerable region. Despite the recent development in climate and hydrology, a comprehensive understanding of hydro climatic variability—particularly its link to global sea surface temperature anomalies— remains limited. Moreover, the dynamics of extreme events such as intense rainfall, floods, and droughts under future climate conditions and uncertainties propagated to hydrological simulations are quite unexplored. Given this gap, this study aims to explore and better understand hydro climatic variability and extreme events under climate change within the Geba Sub-basin, situated in the northern highlands of Ethiopia. To achieve this, an integrated approach was employed—combining statistical analysis of daily long-term hydro climatic data (1981-2017), remote sensing, field surveys, laboratory investigations, and climate–hydrological modeling at the sub-basin scale.