Estimation of coastal aquifer properties: A review of the tidal method based on theoretical solutions

Abstract

Determination of the hydraulic properties of coastal aquifer systems has important implications that are related to the issues such as seawater intrusion, submarine groundwater discharge, migration of contaminants, assessment of water resources, and geotechnical engineering. Over recent decades, many analytical solutions that consider different types of coastal aquifer systems or models have been developed. These solutions can be used as a theoretical basis for the tidal method that characterizes the hydraulic properties of a coastal aquifer system using hydraulic response measurements in an observation well or wells induced by tidal waves in the ocean. The hydraulic properties of an aquifer can be estimated through fitting a series of time-dependent changes of hydraulic head detected in an observation well to those calculated based on theoretical solutions. For simplicity, most theoretical solutions only consider one tidal component and idealized boundary conditions, although in reality multiple tidal components exist simultaneously and boundary conditions can be more complicated. For practical applications of the tidal method and to increase its reliability, multiple tidal components should be considered and models considering more complicated boundary conditions should be developed. In addition, methods that can determine both the hydraulic conductivity and storage coefficient, rather than only the hydraulic diffusivity, that is, the ratio of hydraulic conductivity to storage coefficient of coastal aquifer, should be developed. Cautions should be taken into account when using the tidal method because earth tides and changes in local atmospheric pressure may induce similar tidal fluctuations in the hydraulic head within inland observation wells.

Seasonal drivers and patterns of sediment temperatures in a New England salt marsh

“…The water level ranged from À0.59 m below the ground surface to 1.60 m above the ground surface, with an average water level of À0.20 m relative to ground surface. In the mid marsh, tidal fluctuations were present but dampened due to distance from the tidal channel as the tidal signals are hydraulically diffused through the subsurface (Zhang et al, 2021). The largest water level fluctuations occurred between spring and neap tides.…”

Morphologic, Atmospheric, and Oceanic Drivers Cause Multi‐Temporal Saltwater Intrusion on a Remote, Sand Island

“…High-frequency signals observed in the groundwater level and EC data (from piezometers on Sable Island) are primarily attributed to tides. As tidal phenomena in coastal aquifers have been previously well studied, often for aquifer characterization (M. Zhang et al, 2021), our tidal results are only summarized herein, with more details provided in the electronic supplement. Dominant groundwater level and EC amplitudes in the time domain (Figure S7a in Supporting Information S1) and converted to the frequency domain via Fast Fourier Transform (Figure S7b in Supporting Information S1) align with dominant diurnal and semi-diurnal tidal constituents (M2, S2, K1, and O1), as well as frequencies associated with spring-neap constituents (Text S1 in Supporting Information S1).…”

Analytical study of dual‐porosity coastal aquifer with generalized nonlinear water transfer term

“…These models help determining the sound strategy for the management of water resources. Furthermore, these can be implemented to estimate the hydraulic parameters of the coastal aquifer using the tidal method, that is, the method that applies the tide‐induced head response to identify the hydraulic parameters (Trefry & Johnston, 1998; Xun et al, 2015; Zhang et al, 2021; Zhou, 2008).…”

“…Simulating the tide‐induced head fluctuations in a coastal aquifer has been widely investigated. Understanding the head response in coastal aquifer facilities in application to the stability of saltwater intrusion into coastal engineering (Levanon et al, 2016, 2017; Zhang et al, 2021), characterization of the aquifer and marine contamination (Hester et al, 2019) issues. Much research has been published on tide‐induced head fluctuations for models with different aquifer configurations (Fang et al, 2018; Guo et al, 2007; Huang et al, 2015; Jiao & Tang, 1999; Li et al, 2002; Li & Jiao, 2001; Mahdavi, 2021; Sedghi & Samani, 2010; Tang & Jiao, 2001; Zhao et al, 2019).…”