Analysis of the development of vadose water profiles over deep aquifers with minimal recharge
Abstract
Understanding the processes that draw water from deep aquifers in hyper-arid environments is needed to understand the hydrology of these areas, may influence the design of waste storage facilities located in such environments, and reveals fundamental features of evolving scales of hydrologic processes on earth. Here we seek to provide a physical framework for understanding the process and scales at which water and salt movement take place in this extreme environment. The analysis of [Ross, 1984] and [Selker, 2017] is confirmed and expanded upon to provide a simple algebraic expression, derived from the governing physical processes, predicting the fluxes and extent of such systems. It is found that such unsaturated zone hosts counter-fluxes of downward liquid and upward vapor flow, driven by the geothermal gradient. Net upward transport is about 0.01mm/y from the water table, which is augmented by the depletion of the residual water in the drained soil, resulting in surface fluxes of 1.0, 0.1 and 0.02mm/y after 100y, 10ky, and 150ky. 10-30M years pass before soil dries to depths of 200m. It is found that the influence of capillary flow to the upward transport of water is only influential within less than 5m of the water table, and so is insignificant to the overall flux, but does imply a convergence line where vapor loss is predicted to leave behind salts delivered from above and below to the top of the capillary zone.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H51R1553S
- Keywords:
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- 1818 Evapotranspiration;
- HYDROLOGYDE: 1847 Modeling;
- HYDROLOGYDE: 1855 Remote sensing;
- HYDROLOGYDE: 1878 Water/energy interactions;
- HYDROLOGY