The base flow is the difference between
- AThe total runoff and the direct runoffCorrect
- BThe total runoff and the delayed subsurface runoff
- CThe prompt subsurface runoff and the delayed subsurface runoff
- DThe total runoff and the prompt subsurface runoff
Solution
Concept
Base Flow Separation
Formula
Base Flow = Total Runoff - Direct Runoff
Step-by-step solution
1. Identify total runoff and direct runoff values. 2. Subtract direct runoff from total runoff to get base flow.
Explanation
Total runoff is the combined amount of water moving through a stream, consisting of immediate direct runoff from rainfall and sustained base flow from groundwater. Subtracting the direct runoff from the total runoff leaves only the base flow.
Shortcut
Remember the equation: Total Runoff = Base Flow + Direct Runoff (T = B + D). Therefore, Base Flow = Total Runoff - Direct Runoff (B = T - D).
Common mistake
Students often confuse base flow with delayed subsurface runoff or mistake direct runoff for only prompt subsurface runoff, leading to incorrect selection among options B, C, or D instead of recognizing that base flow is simply total runoff minus direct runoff.
Correct answer: A) The total runoff and the direct runoff