Question

The property of specific retention of water in an aquifer is mainly governed by

• A. Gravity
• B. Capillary forces
• C. Pressure
• D. Pumping

Hint:

Specific retention is controlled by \[ \boxed{ \text{Capillary forces + Molecular attraction} } \] whereas \[ \boxed{ \text{Specific yield}=\text{Water drained by gravity}. } \]

Answer 1

The Correct Option is B

Step 1: Recall what specific retention means.
When water drains out of a saturated soil under gravity, not all of it leaves; a portion clings to the soil grains. That retained fraction is the specific retention.
Step 2: Think about why that water stays behind.
Thin films of water get held onto grain surfaces and in tiny pore throats by capillary and molecular attraction, strong enough to resist the pull of gravity.
Step 3: Eliminate the other forces.
Gravity is actually what tries to drain the water out, not what holds it back, and pressure or pumping have nothing to do with this small-scale retention.
\[ \boxed{\text{Capillary forces}} \]