Description

Simple functions to compute 1D-Ferris equations from sinusoidal periodic signal propagation in a porous medium.

Installation

To install the current version:

git clone https://github.com/pmatran/hdtsa.git
cd hdtsa

Make sure to install all dependencies:

pip install -r requirements.txt

As a test, you can run the provided example.py:

python example.py [-s]

Context

Conceptually, a tidal signal is defined by a periodic signal that propagates in a relatively homogeneous medium : the seawater. Reaching the costline (M) the tidal signal continues to spread in the coastal aquifer. Nevertheless, the costal aquifer is a more complex medium that contains 2 phasis: solid (rock) and liquid/fluide (water).

Therefore, the signal will be affected by 2 phenomenons:

• Attenuation $\alpha$
• Phase shift $\phi$

By extracting the sea levels at the costline (M) thank's to tide gauges records and analyzing the water table records of a given observation well (P) x meters away from the costline during the same time window, it is possible to access the values of the attenuation and phase shift:

Parameter	Variable	Unit	Method	Equation
Attenuation	$\alpha$	[-]	Quadratic Norms Ratio	$e^{-\sqrt(\frac{\omega}{2D})x}$
Phase shift	$\phi$	[T]	Peak matching	$\sqrt(\frac{\omega}{2D})x$

Finally, the 1D propagation equation of a sinusoidal periodic signal in porous media proposed by Ferris,1952 links the calculated $\alpha$ and $\phi$ parameters to the hydraulic diffusivity of the costal aquifer, respectivly, $D_{\alpha}$, $D_{\phi}$.

Get started

# ---- Import modules
import numpy as np
from ferris import attenuation2hd, shift2hd

# ---- Set some observation values
alpha, phi, xc, T = [0.493, 0.333, 371, 1.2e-3]

# ---- Compute hydraulic diffusivities
hd_alpha = attenuation2hd(alpha=alpha, x=xc, T=T)
hd_phi = shift2hd(phi=phi, x=xc, T=T)

# ---- Compute `slope factor` criteria
slope_factor = np.sqrt(hd_alpha/hd_phi)
print(f"Slope factor = {round(slope_factor, 3)}")

Contributing

Bug reports, code contributions, or improvements to the documentation are welcome from the community. Feel free to suggest improvements by working with your own fork version of hdtsa. Go to the project page and hit the Fork button. You will want to clone your fork to your machine:

git clone <url_hdtsa> <hdtsa-yourname>
cd hdtsa-yourname

Ressources

• Determining aquifer characteristics by the tidal method.
• Cyclic fluctuations of water level as a basis for determining aquifer transmissibility
• Hydrogéologie des milieux volcaniques insulaires: apports d'une étude intégrée aux îles Galapagos

⛔ Disclaimer ⛔

➡️This project was created to evaluate git management skills of the owner (@pmatran) by his professor at M2-IASchool (Bordeaux, FRANCE).
➡️However, remember that the provided data are not totally fake and comes from a previous student work proposed by @apryet at ENSEGID school (Bordeaux, FRANCE).

Coffee beaks ☕☕