Salt transport on islands in the Okavango Delta: Numerical investigations

S. Zimmermann, P. Bauer, R. Held, W. Kinzelbach, Jens Honore Walther

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

This study uses a numerical model to investigate the groundwater flow and salt transport mechanisms below islands in the Okavango Delta. Continuous evapotranspiration on the islands results in accumulation of solutes and the formation of a saline boundary layer, which may eventually become unstable. A novel Lagrangian method is employed in this study and compared to other numerical methods. The numerical results support the geophysical observations of density fingering on Thata Island. However, the process is slow and it takes some hundreds of years until density fingering is triggered. The results are sensitive to changes of the hydraulic gradient and the evapotranspiration rate. Small changes may lead to different plume developments. Results further demonstrate that density effects may be entirely overridden by lateral flow on islands embedded in a sufficiently high regional hydraulic gradient.
Keyword: Saline boundary layer,Density-driven groundwater flow,Particle methods,Free convection,Numerical study
Original languageEnglish
JournalAdvances in Water Resources
Volume29
Pages (from-to)11--29
ISSN0309-1708
DOIs
Publication statusPublished - 2006
Externally publishedYes

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