Infiltration rate is always
- Amore than the infiltration capacity
- Bless than the infiltration capacity
- Cequal to or less than the infiltration capacityCorrect
- Dequal to or more than the infiltration capacity
Solution
Concept
Infiltration is water entering the soil. The actual rate depends on how much water is available (rainfall) and the soil's maximum capacity to absorb it.
Formula
f = min(i, fc) where f is infiltration rate, i is rainfall intensity, and fc is infiltration capacity.
Step-by-step solution
1. Understand 'Infiltration Capacity' (fc): This is the maximum speed at which a soil can absorb water when it is fully available. 2. Understand 'Infiltration Rate' (f): This is the actual speed at which water enters the soil at any given time. 3. Case 1: If rainfall intensity (i) is less than the capacity (fc), then all the rain goes into the soil. Here, f = i, so f is less than fc. 4. Case 2: If rainfall intensity (i) is more than the capacity (fc), the soil can only take its maximum limit. Here, f = fc, and the rest becomes runoff. 5. Conclusion: The actual rate (f) can be equal to the capacity or less than it, but it can never exceed the soil's maximum limit. Answer: (C) equal to or less than the infiltration capacity
Explanation
Infiltration capacity is the upper limit of a soil's absorption speed. If it rains lightly, the infiltration rate is just the rainfall rate (less than capacity). If it rains heavily, the rate reaches the capacity limit but cannot go above it.
Why the other options are wrong
A: The actual rate can never exceed the soil's maximum absorption limit. B: This is only true when rainfall is light; it can also be equal to capacity during heavy rain. D: The rate cannot be more than the capacity.
Shortcut
Actual rate can never be more than the maximum capacity.
Common mistake
Students often confuse 'rate' with 'capacity' and think they are always the same.
Correct answer: C) equal to or less than the infiltration capacity