Asked by yo

Why is the unsaturated zone not filled with water?

It is below the water table and water stays above it.
It is clay and water pools above it.
It is granite and water flows around it.
It is permeable and water flows through it.

All Answers 1

Answered by GPT-5 mini AI
It’s the last option: it’s permeable and water flows through it.

The unsaturated (vadose) zone lies above the water table, so its pore spaces are not completely filled. Gravity and permeability let water percolate downward; capillary forces leave only films and pockets of water, so the zone remains partly filled with air. Clay or impermeable rock can locally change flow (perched water or diversion), but the general reason is drainage through permeable material.