The period when soil is saturated and water cannot enter, so flows over the surface.

The period when soil is saturated and water cannot enter, so flows over the surface.

• A. Soil moisture surplus
• B. Interception loss
• C. Field capacity
• D. Wilting point

Answer: (A)

Key idea: when the soil is at field capacity, it cannot store more water, so any additional rainfall cannot infiltrate and must flow over the surface as runoff. This state is called soil moisture surplus. It describes the period during which the soil is saturated and the incoming water is discharged as surface runoff, a form of saturation-excess runoff. Interception loss is water taken by vegetation before reaching the ground, so it doesn’t describe what happens once the soil is saturated. Field capacity is the moisture level the soil holds after drainage, the threshold that determines when surplus begins but is not itself the period of runoff. Wilting point is the low moisture level at which plants wilt, not about runoff generation.

Key idea: when the soil is at field capacity, it cannot store more water, so any additional rainfall cannot infiltrate and must flow over the surface as runoff. This state is called soil moisture surplus. It describes the period during which the soil is saturated and the incoming water is discharged as surface runoff, a form of saturation-excess runoff.

Interception loss is water taken by vegetation before reaching the ground, so it doesn’t describe what happens once the soil is saturated. Field capacity is the moisture level the soil holds after drainage, the threshold that determines when surplus begins but is not itself the period of runoff. Wilting point is the low moisture level at which plants wilt, not about runoff generation.