What specific yield would be expected in a SC aquifer?

What specific yield would be expected in a SC aquifer?

• A. 15%
• B. 5%
• C. 25%
• D. 50%

Answer: (A)

Specific yield is the portion of the saturated water in an aquifer that drains under gravity when the water table falls. In a sand–clay (SC) aquifer, the drainage comes mainly from the coarser, more permeable sand fraction, while the finer clay retains water more tightly and doesn’t contribute much to gravity drainage. That combination typically yields a moderate Sy, commonly around 0.10 to 0.25 for mixed sediments, with 0.15 (15%) being a representative value. So 15% best matches the expected drainage efficiency for an SC aquifer. Values like 5% would be more characteristic of very fine clays, while 25% or 50% exceed what’s typical for most natural SC materials.

Specific yield is the portion of the saturated water in an aquifer that drains under gravity when the water table falls. In a sand–clay (SC) aquifer, the drainage comes mainly from the coarser, more permeable sand fraction, while the finer clay retains water more tightly and doesn’t contribute much to gravity drainage. That combination typically yields a moderate Sy, commonly around 0.10 to 0.25 for mixed sediments, with 0.15 (15%) being a representative value. So 15% best matches the expected drainage efficiency for an SC aquifer. Values like 5% would be more characteristic of very fine clays, while 25% or 50% exceed what’s typical for most natural SC materials.