What term describes the percentage of a formation that is occupied by pores or spaces?

The term that describes the percentage of a formation that is occupied by pores or spaces is porosity. Porosity is a critical concept in geology and hydrology as it directly relates to how much water or other fluids can be stored within a material. It is defined as the ratio of the volume of voids in a material to the total volume of the material, often expressed as a percentage.

Understanding porosity is essential for water operators, as it affects the availability of groundwater in aquifers and impacts the design of water systems regarding storage and flow rates. While permeability and hydraulic conductivity relate to how easily fluids can flow through a porous medium, they focus on the ability of the material to transmit fluids rather than the capacity of void spaces to hold fluids. Specific yield is related to the volume of water that can be drained from a saturated material, but it does not represent the percentage of the total volume that is voids.