Analytic Solutions for Tidal Propagation in Multilayer Coastal Aquifers

Abstract

A new analytic solution is presented for tidal propagation in multilayer coastal aquifers consisting of an arbitrary number of layers. The solution is derived using matrix calculus and may be applied to simulate tidal propagation in systems where aquifer layers are separated by leaky layers of low permeability or in stratified aquifers. The head, amplitude, and phase shift may be simulated for arbitrary tidal components. The transmissivity, storage coefficient, and loading efficiency may be different for every aquifer layer. Similarly, the resistance to vertical flow, storage coefficient, and loading efficiency may be different for every leaky layer. The aquifer system extends an infinite distance below the sea or may end abruptly at the shore line. In the former case, different aquifer and leaky layer properties may be specified below the sea and below the land. A homogeneous unconfined aquifer is simulated with 80 layers to demonstrate that the tidal signal propagates much farther inland in the deeper part than in the shallower part of an unconfined aquifer. This effect is enhanced significantly when layers of low permeability are present in the aquifer, even when these layers are fairly thin, such as clay lenses. The solution is implemented in Python and may be used, for example, to estimate aquifer parameters from head measurements in coastal aquifers.

Combined Multilevel Monitoring and Wavelet Transform Analysis Approach for the Inspection of Ground and Surface Water Dynamics in Shallow Coastal Aquifer

“…Groundwater levels in coastal aquifers are mainly influenced by sea level tidal variations and precipitation, with the respective degree of influence depending on the location of the observation well [8]. The tidal effect on groundwater level decreases with distance from the coast as well as the time lag to sea level increases [21]. The basis of those findings have been established in early works [22,23] with consistent to up to date improvements and a wide range of methodological assumptions on whom tidal methods are founded [24,25].…”

CMBEAR: Python‐Based Recharge Estimator Using the Chloride Mass Balance Method in Australia

“…CMBEAR is implemented in a simple to use Jupyter (Python) notebook. Python was selected as it is freely available and simple to install (e.g., using the Anaconda installer, https://docs.anaconda.com/anaconda/install/) and has been widely used for data analysis in hydrogeology (e.g., Peeters 2014; Bakker et al 2016; Kurylyk and Irvine 2016; Feo et al 2018; Bakker 2019; Collenteu et al 2019; Domanski et al 2020). Specifically, the paper (1) describes the inputs and outputs of CMBEAR; (2) compares the outputs of the tool against published recharge investigations; and (3) presents example applications of the tool utilizing large data sets.…”

Hydrogeological Characterization of Coastal Aquifer on the Basis of Observed Sea Level and Groundwater Level Fluctuations: Neretva Valley Aquifer, Croatia

“…The role of outlet capping when combined with multilayered coastal aquifer was investigated by Guo et al [16]. In 2019, Bakker [9] presented a novel analytical solution to define transient nature of groundwater head within the multilayered aquifer. Li and Jiao [21] demonstrated the importance of leakage effect, separately for offshore and inland aquifer systems.…”

“…Independently of the observation technique used, monitored time series are a result of a simultaneous effect of both tidally induced changes and barometric changes, thus defining water level found within the well open to atmosphere. Because some of the tidal methods imply the knowledge of loading efficiency [9,14,26], barometric efficiency, BE, has to be determined to characterize tidally induced changes inland from the shoreline. The topic of excluding the effects of barometric pressure from observed groundwater level was of interest in several publications [41][42][43][44][45][46][47][48][49][50][51], whereas BE determination can be approached by time domain or frequency domain analysis [50].…”