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Run-off Coefficient Formula:
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The Run-off Coefficient is a dimensionless coefficient that represents the ratio of runoff depth to rainfall depth. It indicates what portion of precipitation becomes surface runoff rather than being absorbed or evaporated.
The calculator uses the Run-off Coefficient formula:
Where:
Explanation: The formula calculates the proportion of rainfall that becomes surface runoff, with values ranging from 0 (all rainfall absorbed) to 1 (all rainfall becomes runoff).
Details: Accurate run-off coefficient calculation is crucial for hydrological modeling, urban drainage design, flood prediction, and water resource management. It helps engineers design appropriate drainage systems and manage stormwater effectively.
Tips: Enter runoff depth and rainfall depth in meters. Both values must be positive, and rainfall depth must be greater than zero for valid calculation.
Q1: What factors affect the run-off coefficient?
A: Surface type, slope, soil permeability, vegetation cover, and rainfall intensity all influence the run-off coefficient value.
Q2: What are typical run-off coefficient values?
A: Values range from 0.05-0.10 for forested areas, 0.20-0.35 for lawns, 0.70-0.95 for paved surfaces, and 0.85-0.95 for roofs.
Q3: How is run-off coefficient used in engineering?
A: It's used to size drainage pipes, design stormwater management systems, and predict flood volumes in watershed modeling.
Q4: Does the run-off coefficient change with rainfall intensity?
A: Yes, higher intensity rainfall typically produces higher run-off coefficients as the ground becomes saturated more quickly.
Q5: How accurate is this calculation method?
A: While the formula is mathematically precise, actual field conditions may vary due to complex hydrological processes not captured by this simple ratio.