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Spatially varying dispersion to model breakthrough curves
1Department of Geophysics, Yunnan University, Kunming, Yunnan 650091, P.R. China. guangquanli74@gmail.com
Ground Water
|December 15, 2010
Summary
Karst conduit water transport is complex, involving mixing of contaminated and clean water. A new model shows spatially varying dispersion significantly impacts solute movement, with large dispersivity indicating strong conduit-matrix interaction.
Area of Science:
- Hydrogeology
- Environmental Science
- Geochemistry
Background:
- Karst conduit water flow is a mix of surface and matrix water.
- Transport is governed by advection, mixing, and retention-release processes.
Purpose of the Study:
- Develop a karst transport model incorporating advection, variable dispersion, and matrix dilution.
- Analyze the impact of spatially varying dispersion on solute transport in karst systems.
Main Methods:
- Developed a karst transport model using transformation of variables to derive Green's functions.
- Applied the model to simulate solute transport and compared with dye-tracing experiments.
Main Results:
- Spatially varying dispersion causes significant skewness and long tailing in breakthrough curves.
- Conduit dispersivity up to 400 m was observed in a Florida dye-tracing experiment.
- Large dispersivity suggests strong solute exchange between conduit and matrix or complex flow paths.
Conclusions:
- Taylor dispersion is not the primary mechanism in karst conduit transport.
- Spatially varying dispersion effectively models the complex retention-release processes between mobile and immobile water.
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