Surface Runoff Increase from Impervious Surfaces

Steps:

• Identify initial runoff percentage before houses (e.g., 30% from permeable land).
• Determine new runoff percentage after houses (e.g., 40% due to impervious coverage).
• Calculate absolute difference: 40% - 30% = 10 percentage points.
• Compute percentage increase relative to original: (10 / 30) × 100% = 33%.

Not enough information: No specific percentages provided for before/after runoff.

Why A is correct:

• Matches calculation of relative increase in runoff from added impervious surfaces, per hydrology principles.

Why the others are wrong:

• B: Wrong increase value; 43% doesn't fit typical data.
• C: Incorrect; runoff increases, doesn't decrease to 33%.
• D: Incorrect; runoff increases, doesn't decrease to 43%.

Final answer: A