Presenter(s)

Rose H. Weisgerber

Comments

Presentation: 9:00-10:15, Kennedy Union Ballroom

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Description

Understanding the link between precipitation and groundwater is vital for ensuring water resources' availability, reliability, and sustainability, particularly in arid regions such as Ethiopia that are vulnerable to climate change. To understand the main controls of groundwater recharge and estimate the seasonal contribution of precipitation, we conducted a comprehensive water isotope study in Hosanna, southern Ethiopia. Due to the complex interconnection of climate, rainfall, and groundwater recharge in this region, we used multiple approaches. Using stable isotopes of Hydrogen (δD) and Oxygen (δ18O) as a conservative tracer, we developed a local meteoric water line (LMWL) and employed isotope mass balance. These analyses provide a quantitative estimate of groundwater recharged and recharge mechanisms.Additionally, Hybrid Single Lagrangian Integrated Trajectory (HYSPLIT) modeling, correlation analysis of climate data, and intensity threshold analysis shed further light on the source of moisture, atmospheric, and climatic controls. Our findings indicate that precipitation in Hosanna mainly originates from recycled moisture sources, evidenced by d-excess, with the oceanic advected moisture seasonally alternating between the North and South Indian Oceans. The wet season provides most of the annual precipitation, with groundwater recharge biased (~65.5%) towards the wet season. However, the intensity threshold analysis suggests extreme rainfall events had the most significant impact on groundwater recharge. The amount-weighted δ18O values of five extreme precipitation events occur during the wet season and have a similar isotopic composition (0.86‰ difference) with the groundwater δ18O values. While wet season and high-intensity precipitation account for most groundwater recharge, slow diffuse recharge, focused recharge from rivers, and dry season precipitation account for the rest of groundwater recharge. This study establishes the source and main contributors of regional groundwater recharge in Hosanna. It provides invaluable information for surface water contaminant transport, water resource management, sustainable development, and climate change adaptation strategies.

Publication Date

4-17-2024

Project Designation

Capstone Project

Primary Advisor

Zelalem K. Bedaso

Primary Advisor's Department

Geology

Keywords

Stander Symposium, College of Arts and Sciences

Institutional Learning Goals

Scholarship

Quantifying the impacts of precipitation seasonality and intensity on groundwater availability in Hosanna, Ethiopia.

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