What does specific yield measure?

Specific yield is a key concept in hydrogeology that quantifies the ability of a porous material, such as soil or rock, to transmit water. It specifically measures the amount of water that can drain from a material under the influence of gravity. This means that when water is allowed to seep out from a fully saturated material, the specific yield is the volume of water that drains per unit volume of the material.

This characteristic is crucial for understanding groundwater movement and storage capacities of aquifers. It provides insight into how much groundwater can be effectively extracted from a saturated zone and can influence water supply decisions and aquifer management.

The other options, while related to water and groundwater concepts, do not accurately define specific yield. The volume of water available for supply pertains to the total quantity that can be drawn from a source, the rate of groundwater recharge deals with how quickly groundwater is replaced, and the total volume of a groundwater aquifer describes the overall capacity of an aquifer without accounting for the actual water that can be extracted by gravity drainage. Each of these aspects plays a different role in water resource management, but they do not align with the definition of specific yield.