Question

Which aquifer property is associated with specific yield of the aquifer?

• A. Storativity
• B. Permeability
• C. Porosity
• D. Transmissivity

Hint:

• Porosity ($n$): Total void space in a material.
• Specific Yield (S$_y$): Fraction of water in a saturated material that drains by gravity.
• Specific Retention (S$_r$): Fraction of water retained against gravity.
• Relationship: Porosity ($n$) = Specific Yield (S$_y$) + Specific Retention (S$_r$).
• Therefore, specific yield is directly related to and a component of porosity.
• Storativity of an unconfined aquifer is approximately equal to its specific yield.

Answer 1

The Correct Option is A

To determine which aquifer property is associated with the specific yield of the aquifer, we need to define each term and understand their relationships.

1. Understanding the Concepts:

- Aquifer: A geological formation that can store and transmit a significant quantity of groundwater.
- Porosity: The ratio of the volume of void spaces to the total volume of the rock or soil. It indicates the amount of water the material can potentially hold.
- Permeability: A measure of the ability of a rock or soil to transmit water. It depends on the size and interconnectedness of the pore spaces.
- Specific Yield (Sy): The ratio of the volume of water that an aquifer releases by gravity drainage to the total volume of the aquifer. It represents the drainable porosity.
- Storativity (S): The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in hydraulic head. For unconfined aquifers, storativity is approximately equal to specific yield.
- Transmissivity (T): A measure of the ability of an aquifer to transmit water through its entire thickness. It is the product of hydraulic conductivity and aquifer thickness.

2. Relationships Between Properties:

- Porosity indicates the total void space, but not all of that water is released due to gravity. - Permeability allows water to move, but it's not directly tied to the *amount* of water released by gravity. - Storativity describes the water released from storage. In *unconfined aquifers*, storativity is approximately equal to specific yield. This is the strongest connection among the choices. - Transmissivity relates to the *rate* of water flow, not the amount released from storage.

3. Determining the Correct Association:

Specific yield is directly related to how much water an unconfined aquifer releases when drained by gravity. In unconfined aquifers, this value is closely linked to the storativity of the aquifer. Storativity is the volume of water released (or stored) per unit area per unit change in head.

Final Answer:

The aquifer property associated with the specific yield of the aquifer is Storativity.