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New insights into the flow dynamics of a deep freshwater aquifer in the semi-arid and saline Cuvelai-Etosha Basin, Northern Namibia: Results of a multi-environmental tracer study
Journal Article·· Journal of Hydrology. Regional Studies
Study region A paleo-megafan system of the Cubango River in the northern parts of the semi-arid Cuvelai-Etosha Basin, shared by Angola and Namibia. It hosts a deep freshwater aquifer, the so-called Kalahari-Ohangwena 2 (KOH-2), with the potential to resolve the imminent regional water supply shortages. Study focus Hydrogeochemical and multi-environmental tracer studies incorporating the use of age tracers 14C, 36Cl, 81Kr and 4He to determine the age of groundwater and provide insights into the flow dynamics of the KOH-2. New hydrological insights for the region Stable water isotopes and noble gas thermometry show that in a period with higher rainfall and recharge, temperatures were at least 3 – 4 °C lower than today. Several arguments led to the conclusion that younger groundwater, possibly of an age of 35,000 years, is mixed with ancient saline pore water. These include: 1) the correlation of measured 36Cl and 81Kr ratios, as well as 4He concentrations, using a binary mixing model, and 2) the substantial variation in 81Kr ages, ranging from 40,000 to 170,000 years, over relatively short distances—a phenomenon challenging to explain by advective groundwater flow equations. Consequently, the ages derived from 81Kr measurements serve as indicators of the extent of freshening and therefore describe mixing ages rather than absolute travel times.
Bäumle, Roland, et al. "New insights into the flow dynamics of a deep freshwater aquifer in the semi-arid and saline Cuvelai-Etosha Basin, Northern Namibia: Results of a multi-environmental tracer study." Journal of Hydrology. Regional Studies, vol. 52, Feb. 2024. https://doi.org/10.1016/j.ejrh.2024.101721
Bäumle, Roland, Purtschert, Roland, Mueller, Peter, Krekeler, Torsten, Zappala, Jake C., Matsumoto, Takuya, Gröger-Trampe, Jens, Koeniger, Paul, Vockenhuber, Christof, Romeo, Nicoló, & Mabry, Jennifer (2024). New insights into the flow dynamics of a deep freshwater aquifer in the semi-arid and saline Cuvelai-Etosha Basin, Northern Namibia: Results of a multi-environmental tracer study. Journal of Hydrology. Regional Studies, 52. https://doi.org/10.1016/j.ejrh.2024.101721
Bäumle, Roland, Purtschert, Roland, Mueller, Peter, et al., "New insights into the flow dynamics of a deep freshwater aquifer in the semi-arid and saline Cuvelai-Etosha Basin, Northern Namibia: Results of a multi-environmental tracer study," Journal of Hydrology. Regional Studies 52 (2024), https://doi.org/10.1016/j.ejrh.2024.101721
@article{osti_2368554,
author = {Bäumle, Roland and Purtschert, Roland and Mueller, Peter and Krekeler, Torsten and Zappala, Jake C. and Matsumoto, Takuya and Gröger-Trampe, Jens and Koeniger, Paul and Vockenhuber, Christof and Romeo, Nicoló and others},
title = {New insights into the flow dynamics of a deep freshwater aquifer in the semi-arid and saline Cuvelai-Etosha Basin, Northern Namibia: Results of a multi-environmental tracer study},
annote = {Study region A paleo-megafan system of the Cubango River in the northern parts of the semi-arid Cuvelai-Etosha Basin, shared by Angola and Namibia. It hosts a deep freshwater aquifer, the so-called Kalahari-Ohangwena 2 (KOH-2), with the potential to resolve the imminent regional water supply shortages. Study focus Hydrogeochemical and multi-environmental tracer studies incorporating the use of age tracers 14C, 36Cl, 81Kr and 4He to determine the age of groundwater and provide insights into the flow dynamics of the KOH-2. New hydrological insights for the region Stable water isotopes and noble gas thermometry show that in a period with higher rainfall and recharge, temperatures were at least 3 – 4 °C lower than today. Several arguments led to the conclusion that younger groundwater, possibly of an age of 35,000 years, is mixed with ancient saline pore water. These include: 1) the correlation of measured 36Cl and 81Kr ratios, as well as 4He concentrations, using a binary mixing model, and 2) the substantial variation in 81Kr ages, ranging from 40,000 to 170,000 years, over relatively short distances—a phenomenon challenging to explain by advective groundwater flow equations. Consequently, the ages derived from 81Kr measurements serve as indicators of the extent of freshening and therefore describe mixing ages rather than absolute travel times.},
doi = {10.1016/j.ejrh.2024.101721},
url = {https://www.osti.gov/biblio/2368554},
journal = {Journal of Hydrology. Regional Studies},
issn = {ISSN 2214-5818},
volume = {52},
place = {United States},
publisher = {Elsevier},
year = {2024},
month = {02}}