Spectral decomposition of periodic ground water fluctuation in a coastal aquifer

Shih, David Ching‐Fang; Lin, Gwo‐Fong; Jia, Yee-Ping; Chen, Yue‐Gau; Wu, Yih‐Min

doi:10.1002/hyp.6781

Cited by 17 publications

(4 citation statements)

References 14 publications

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“…Propagation of tidal signals through coastal aquifers has been extensively studied (e.g., Carr & Van Der Kamp, ; Ferris, ; Guo et al, ; Hsieh et al, ; Jacob, ; Kim et al, ; Nielsen, ; Shih et al, ; Turner et al, ). As a tidal signal propagates landward through an aquifer, the signal becomes increasingly damped (reduced amplitude) and delayed (phase shift).…”

Section: Introductionmentioning

confidence: 99%

Analysis of Tide and Offshore Storm‐Induced Water Table Fluctuations for Structural Characterization of a Coastal Island Aquifer

Trglavcnik

Morrow

Weber

et al. 2018

Water Resources Research

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Analysis of water table fluctuations can provide important insight into the hydraulic properties and structure of a coastal aquifer system including the connectivity between the aquifer and ocean. This study presents an improved approach for characterizing a permeable heterogeneous coastal aquifer system through analysis of the propagation of the tidal signal, as well as offshore storm pulse signals through a coastal aquifer. Offshore storms produce high wave activity, but are not necessarily linked to significant onshore precipitation. In this study, we focused on offshore storm events during which no onshore precipitation occurred. Extensive groundwater level data collected on a sand barrier island (Sable Island, NS, Canada) show nonuniform discontinuous propagation of the tide and offshore storm pulse signals through the aquifer with isolated inland areas showing enhanced response to both oceanic forcing signals. Propagation analysis suggests that isolated inland water table fluctuations may be caused by localized leakage from a confined aquifer that is connected to the ocean offshore but within the wave setup zone. Two‐dimensional groundwater flow simulations were conducted to test the leaky confined‐unconfined aquifer conceptualization and to identify the effect of key parameters on tidal signal propagation in leaky confined‐unconfined coastal aquifers. This study illustrates that analysis of offshore storm signal propagation, in addition to tidal signal propagation, provides a valuable and low resource approach for large‐scale characterization of permeable heterogeneous coastal aquifers. Such an approach is needed for the effective management of coastal environments where water resources are threatened by human activities and the changing climate.

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Section: Introductionmentioning

confidence: 99%

Analysis of Tide and Offshore Storm‐Induced Water Table Fluctuations for Structural Characterization of a Coastal Island Aquifer

Trglavcnik

Morrow

Weber

et al. 2018

Water Resources Research

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“…Based on the natural variation in the hydraulic head, there is a need for spectral decomposition due to the often wide distribution of various frequencies. Previous studies have used the pure statistical technique of cross spectra in conjunction with coherence but which does not recognize the boundary value problem including the physical-mathematical model incorporated in the boundary value formulation, to identify the significant components in the frequency domain between two time series of the river stage and groundwater hydraulic head (Shih et al, 2008;Shih & Lin, 2004). By contrast, the spectral decomposition proposed in this paper recognizes a physical-mathematical model (the scaling factor) explaining the relationship between two observed power spectra, which is reflected in equations ( 9) and ( 14).…”

Section: 1029/2018wr024639mentioning

confidence: 99%

Spectral Analysis of River Resistance and Aquifer Diffusivity in a River‐Confined Aquifer System

Wang

Wörman

2019

Water Resources Research

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Hydraulic connections between a river and an adjacent aquifer are controlled by the river resistance and aquifer diffusivity. In this paper, we derive a spectral solution linking the power spectrum of river stage fluctuations to that of the hydraulic head of a confined aquifer by means of a physical scaling factor. The physical scaling factor represents an algebraic expression of the river resistance and aquifer diffusivity and is included in an exact spectral solution derived herein. Statistical measures of the aquifer diffusivity and river resistance are provided by fitting the solution versus observed groundwater hydraulic head obtained at several distances and/or frequencies. At a study site in the middle reach of the Yangtze River and downstream of the Three Gorges Dam in China, we find systematic damping of the hydraulic head variations with distance from the river, which follows a fractal pattern driven by the river stage. In general, the estimated parameters are consistent with results reported in the literature, which supports the validity of the proposed spectral approach, although the paper discusses advantages and limitations due to application conditions.

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“…Here, we use water level records from paired stream and groundwater monitoring sites to better understand stream-groundwater connectivity over a range of timescales from minutes to seasons. While similar in many respects to previous analyses of water levels in confined aquifers (Shih et al, , 2008, our study focuses on unconfined aquifers that are subject to both vertical infiltration and lateral propagation of hydraulic head signals. We begin by examining general regional trends of water table position and head gradient between streams and aquifers using annual average statistics.…”

Section: Introductionmentioning

confidence: 99%

Groundwater‐stream connectivity from minutes to months across United States basins as revealed by spectral analysis

Clyne

Sawyer

2022

Hydrological Processes

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Stream corridors are dynamic places where streams and aquifers are connected and interact to various degrees, depending on geology, climate, stream morphology, and water use. Water table fluctuations propagate through the unconfined aquifer and are linked with changes in solute export to streams and biogeochemical transformations in floodplain soils. Through publicly available USGS data, this study aims to better understand the behaviour of stream‐groundwater connectivity and water table fluctuations by analysing continuous time series of water levels from 17 pairs of stream gauges and nearby (<100 m) groundwater monitoring wells. Sites are located within 8 of 18 major hydrologic units (HUC‐2) across the contiguous United States and span a variety of stream sizes, climates, and land use practises. More than 50% of sites have a water table that remains within 3 m of the land surface year‐round. Energy spectral densities and cross‐wavelet transformations generally reveal strong coherence between the water table and stream stage over daily to monthly periods. The transfer function, which describes relative variations between the water table and stream stage, shows that 10 of 17 sites are more stream‐dominated at daily and monthly frequencies, meaning that water level fluctuations are greater in the stream and propagate into the aquifer. Only 1 of 17 sites is more groundwater‐dominated at daily and monthly frequencies, meaning that water level fluctuations are greater in the aquifer. This study shows the utility of frequency‐domain analysis for revealing specific timescales of stream‐aquifer interaction.

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Spectral decomposition of periodic ground water fluctuation in a coastal aquifer

Cited by 17 publications

References 14 publications

Analysis of Tide and Offshore Storm‐Induced Water Table Fluctuations for Structural Characterization of a Coastal Island Aquifer

Analysis of Tide and Offshore Storm‐Induced Water Table Fluctuations for Structural Characterization of a Coastal Island Aquifer

Spectral Analysis of River Resistance and Aquifer Diffusivity in a River‐Confined Aquifer System

Groundwater‐stream connectivity from minutes to months across United States basins as revealed by spectral analysis

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