Question

Movement of water into soil at the surface is called

• A. Lateral flow
• B. Infiltration
• C. Seepage
• D. Percolation

Hint:

Infiltration = Surface entry of water into soil.
Percolation = Downward movement within the soil profile.
Seepage = Flow through porous boundaries/dams.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The hydrological cycle distinguishes between the entry of water across the soil surface boundary versus downward movement within the soil profile.
Key Formula or Approach:
\[ f = -K(\theta) \frac{\partial H}{\partial z} \quad \text{(Darcy's Law for Infiltration)} \]

Step 2: Detailed Explanation:
Definitions of water movement terms in soil physics:
1. Infiltration: The entry of water across the atmosphere-soil boundary layer at the ground surface into the soil matrix.
2. Percolation: The downward vertical movement of water through saturated or unsaturated soil layers within the soil profile under gravity.
3. Seepage: The slow lateral/subsurface movement of water through porous media (e.g., through earthen canal banks or dam bodies).
4. Interflow Lateral flow: Lateral downslope flow within the upper soil horizons.

Step 3: Final Answer:
Therefore, the entry of water into soil at the surface is Infiltration, corresponding to option (B).