EOS305_2024_2025_Lecture_Slides_008

Groundwater Hydrogeology

The study of the laws governing the movement of subterranean water, including its mechanical, chemical, and thermal interactions with the porous solid.

Water Cycle

The continuous movement of water within the Earth and atmosphere, involving processes such as evaporation, condensation, and precipitation.

Porosity (n)

The percentage of void space in a rock or sediment, calculated as Volume of voids/Total Volume.

Effective Porosity (ne)

The percentage of interconnected pore space in a substance, indicating how much pore space can actually transmit fluids.

Primary Porosity

Void space that is formed simultaneously with the rock or sediment.

Secondary Porosity

Void space that develops after the formation of the rock or sediment, usually due to processes like faulting or dissolution.

Hydraulic Head (h)

The total height of water in a well and is comprised of pressure head and elevation head.

Darcy's Law

A fundamental equation describing groundwater flow, stating that discharge is proportional to the hydraulic gradient and the area through which it flows.

Hydraulic Conductivity (K)

A measure of how easily a fluid can move through a porous medium, often expressed in units of velocity.

Aquifer

A saturated permeable geologic unit that can transmit significant quantities of water under ordinary hydraulic gradients.

Unconfined Aquifer

An aquifer whose upper boundary is the water table and is in direct contact with the surface.

Confined Aquifer

An aquifer confined between two low-permeability layers, with water under pressure that can rise above the top of the aquifer.

Storativity (S)

The volume of water an aquifer releases from storage, or takes into storage, per unit surface area, per unit change in head.

Transmissivity (T)

The discharge through a vertical strip of porous medium one unit wide and extending through the full saturated thickness under unit hydraulic gradient.