Do equations for groundwater flow refer to water density?

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SUMMARY

The discussion centers on Darcy's law, which calculates the flux of water through a given area, highlighting its ambiguity regarding the relationship between water density in soil and water velocity. Participants assert that while Darcy's law uses superficial velocity driven by a pressure gradient, it does not explicitly account for the density of water. The conversation also touches on environmental testing scenarios, particularly in hydrologically active areas, where factors like layer crush resistance and pore availability are more critical than density. The relationship between flow velocity and flux is clarified with the equation u = q / φ, where u is flow velocity, q is Darcy flux, and φ is porosity.

PREREQUISITES
  • Understanding of Darcy's law and its applications in hydrogeology.
  • Familiarity with concepts of flux, velocity, and porosity in fluid dynamics.
  • Knowledge of environmental testing methodologies related to groundwater.
  • Basic grasp of pressure gradients and their effects on fluid movement.
NEXT STEPS
  • Research the implications of Darcy's law in various soil types and conditions.
  • Explore advanced groundwater flow equations that incorporate density and velocity.
  • Investigate environmental impacts of groundwater flow in industrial areas.
  • Learn about the relationship between porosity and fluid flow in porous media.
USEFUL FOR

Hydrologists, environmental engineers, and researchers involved in groundwater flow analysis and environmental impact assessments will benefit from this discussion.

Stephen Tashi
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TL;DR
Do the equations for groundwater flow contain terms representing the density of water in the soil?
As I understand Darcy's law, it computes the flux of water through an area. The same value of flux can be the realized by different combinations of a density of water in the soil and the velocity of that water. So. as far as I can see, Darcy's law is ambiguous about which combination of density and velocity occurs. Is that a correct interpretation? Are there other equations that deal with the density and velocity?
 
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Darcy’s law refers to the superficial velocity of the water through the medium, driven by a pressure gradient.
 
Stephen Tashi said:
Summary:: Do the equations for groundwater flow contain terms representing the density of water in the soil?

As I understand Darcy's law, it computes the flux of water through an area. The same value of flux can be the realized by different combinations of a density of water in the soil and the velocity of that water. So. as far as I can see, Darcy's law is ambiguous about which combination of density and velocity occurs. Is that a correct interpretation? Are there other equations that deal with the density and velocity?
While doing environmental testing, underground leaching of an old industrial landfill in the Seattle area (very hydrologically active glacial loess). The area is largely layers of sand (porous) and clay (impervious). The steep hillsides slide when Earth movement liquifies sand layer. Density seems irrelevant as limiting low density is determined by layer "crush resistance" and pore availability. Some of the EPA toxics were delayed vs water so water flow not used but toxics mapping was similar.
 
Wikipedia said:
This quantity K, often referred to as the Darcy flux or Darcy velocity, is not the velocity at which the fluid is traveling through the pores. The flow velocity (u) is related to the flux (q) by the porosity (φ) and takes the form u = q / φ;
https://en.wikipedia.org/wiki/Darcy's_law#Description
 

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