Estimating hydraulic properties from tidal attenuation in the Northern Guam Lens Aquifer, territory of Guam, USA
Hydrogeology Journal
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Abstract
Tidal-signal attenuations are analyzed to compute hydraulic diffusivities and estimate regional hydraulic conductivities of the Northern Guam Lens Aquifer, Territory of Guam (Pacific Ocean), USA. The results indicate a significant tidal-damping effect at the coastal boundary. Hydraulic diffusivities computed using a simple analytical solution for well responses to tidal forcings near the periphery of the island are two orders of magnitude lower than for wells in the island’s interior. Based on assigned specific yields of ~0.01–0.4, estimated hydraulic conductivities are ~20–800 m/day for peripheral wells, and ~2,000–90,000 m/day for interior wells. The lower conductivity of the peripheral rocks relative to the interior rocks may best be explained by the effects of karst evolution: (1) dissolutional enhancement of horizontal hydraulic conductivity in the interior; (2) case-hardening and concurrent reduction of local hydraulic conductivity in the cliffs and steeply inclined rocks of the periphery; and (3) the stronger influence of higher-conductivity regional-scale features in the interior relative to the periphery. A simple numerical model calibrated with measured water levels and tidal response estimates values for hydraulic conductivity and storage parameters consistent with the analytical solution. The study demonstrates how simple techniques can be useful for characterizing regional aquifer properties.
Suggested Citation
Rotzoll, K., Gingerich, S.B., Jenson, J.W., El-Kadi, A.I., 2013, Estimating hydraulic properties from tidal attenuation in the Northern Guam Lens Aquifer, territory of Guam, USA: Hydrogeology Journal, v. 21, no. 3, p. 643-654, https://doi.org/10.1007/s10040-012-0949-9.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Estimating hydraulic properties from tidal attenuation in the Northern Guam Lens Aquifer, territory of Guam, USA |
| Series title | Hydrogeology Journal |
| DOI | 10.1007/s10040-012-0949-9 |
| Volume | 21 |
| Issue | 3 |
| Publication Date | January 15, 2013 |
| Year Published | 2013 |
| Language | English |
| Publisher | Springer |
| Publisher location | http://www.springer.com |
| Contributing office(s) | Pacific Islands Water Science Center |
| Description | 12 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Hydrogeology Journal |
| First page | 643 |
| Last page | 654 |
| Country | Guam |