Final answer:
Permeability is the ability of a rock or soil to allow fluids to flow through it, which is crucial for the movement and storage of groundwater in the Earth's subsurface.
Step-by-step explanation:
​​Permeability is the capacity of a rock or soil to transmit a fluid. The concept of permeability is crucial in understanding how groundwater moves through the Earth's subsurface.
While porosity refers to the amount of open space within rock that may hold fluid, permeability specifically looks at the ability of the rock to allow fluids to flow through it.
Such a flow depends on the size of the pores within the rock and how well those pores are connected. Permeable rocks, such as certain sedimentary rocks like sandstone, are capable of transmitting water and make suitable aquifers, which are geological units that can yield significant amounts of water.
In contrast, impermeable rocks act as confining layers that hinder fluid movement.
The water table is also an important concept, as it marks the boundary between rock and soil's unsaturated zone above and the saturated zone below where all the pore spaces are filled with water.