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Estimating the Ground Water Resources of Atoll Islands
Department of Civil and Environmental Engineering, Colorado State University, 1372 Campus Delivery, Fort Collins, CO 80523, USA
Water and Environmental Research Institute of the Western Pacific (WERI), University of Guam, Mangilao, Guam 96923, USA
* Author to whom correspondence should be addressed.
Received: 1 December 2009; in revised form: 4 January 2010 / Accepted: 8 January 2010 / Published: 14 January 2010
Abstract: Ground water resources of atolls, already minimal due to the small surface area and low elevation of the islands, are also subject to recurring, and sometimes devastating, droughts. As ground water resources become the sole fresh water source when rain catchment supplies are exhausted, it is critical to assess current groundwater resources and predict their depletion during drought conditions. Several published models, both analytical and empirical, are available to estimate the steady-state freshwater lens thickness of small oceanic islands. None fully incorporates unique shallow geologic characteristics of atoll islands, and none incorporates time-dependent processes. In this paper, we provide a review of these models, and then present a simple algebraic model, derived from results of a comprehensive numerical modeling study of steady-state atoll island aquifer dynamics, to predict the ground water response to changes in recharge on atoll islands. The model provides an estimate thickness of the freshwater lens as a function of annual rainfall rate, island width, Thurber Discontinuity depth, upper aquifer hydraulic conductivity, presence or absence of a confining reef flat plate, and in the case of drought, time. Results compare favorably with published atoll island lens thickness observations. The algebraic model is incorporated into a spreadsheet interface for use by island water resources managers.
Keywords: atoll; island hydrology; numerical modeling; drought
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MDPI and ACS Style
Bailey, R.T.; Jenson, J.W.; Olsen, A.E. Estimating the Ground Water Resources of Atoll Islands. Water 2010, 2, 1-27.
Bailey RT, Jenson JW, Olsen AE. Estimating the Ground Water Resources of Atoll Islands. Water. 2010; 2(1):1-27.
Bailey, Ryan T.; Jenson, John W.; Olsen, Arne E. 2010. "Estimating the Ground Water Resources of Atoll Islands." Water 2, no. 1: 1-27.