Closed‐Form Approximations for Two‐Dimensional Groundwater Age Patterns in a Fresh Water Lens |
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| Authors: | Janek Greskowiak Tania Röper Vincent EA Post |
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| Institution: | 1. Corresponding author: Department of Biology and Environmental Sciences, Carl‐von‐Ossietzky University of Oldenburg, Carl‐von‐Ossietzky‐Stra?e 9‐11, D‐26129 Oldenburg, Germany;2. (49) 441‐798‐3260;3. fax: (49) 441‐798‐3769;4. janek.greskowiak@uni-oldenburg.de;5. Department of Biology and Environmental Sciences, Carl‐von‐Ossietzky University of Oldenburg, Germany.;6. National Centre for Groundwater Research and Training/School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia. |
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| Abstract: | Simple closed‐form approximations are presented for calculating the steady‐state groundwater age distribution in two‐dimensional vertical cross sections of idealized fresh water lenses overlying salt water, for aquifers that are vertically semi‐infinite and of finite thickness. The approximations are developed on the basis of existing one‐dimensional analytical solutions for travel‐time calculation in fresh water lenses and approximate streamline formulations. The two‐dimensional age distributions based on the closed‐form solutions match convincingly with numerical simulations. As expected, notable deviations from the numerical solution are encountered at the groundwater flow divide and when submarine groundwater discharge occurs. Ratios of recharge over hydraulic conductivities are varied to explore how the magnitude of the deviations changes, and it is found that the approximate closed‐form solutions perform well over a range of conditions found in natural systems. |
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