Estimating hydraulic properties from tidal attenuation in the Northern Guam Lens Aquifer, territory of Guam, USA
Estimating hydraulic properties from tidal attenuation in the Northern Guam Lens Aquifer, territory of Guam, USA
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DOI：
10.1007/s10040-012-0949-9
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发表时间：
2013-01
影响因子：
2.8
通讯作者：
K. Rotzoll;S. Gingerich;J. Jenson;A. El-Kadi
中科院分区：
文献类型：
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作者：
K. Rotzoll;S. Gingerich;J. Jenson;A. El-Kadi
对潮汐信号衰减进行了分析，以计算水力扩散系数和估计美国关岛领土(太平洋)北部关岛透镜含水层的区域水力传导性。结果表明，近岸海域存在明显的减潮效应。用一个简单的解析解计算岛屿外围附近的井对潮汐强迫的响应的水力扩散率比岛内的井低两个数量级。根据指定的比产量∼0.01-0.4，估计周边井的水力传导度为∼20-800米/天，内部井为∼2,000-90,000米/天。岩溶演化效应最好地解释了外围岩石相对于内部岩石的低导电性：(1)内部水平导水率的溶解增强；(2)外围悬崖和急倾斜岩石局部导水率的硬化和同时降低；(3)内部相对外围较高导电率的区域尺度特征的较强影响。根据实测水位和潮汐响应校准的一个简单的数值模型估计的水力传导性和储存参数的值与解析解一致。这项研究表明，简单的技术对于描述区域含水层的特性是多么有用。
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.