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Runoff Equation:
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Runoff calculation is a fundamental concept in hydrology that determines the amount of water that flows over the land surface rather than being absorbed into the ground. It's calculated by subtracting losses (infiltration, evaporation, etc.) from total rainfall.
The calculator uses the basic runoff equation:
Where:
Explanation: This simplified equation provides a basic estimation of surface runoff by accounting for water that doesn't infiltrate into the soil or evaporate back into the atmosphere.
Details: Accurate runoff calculation is essential for flood prediction, water resource management, urban planning, agricultural irrigation design, and environmental impact assessments.
Tips: Enter rainfall and losses values in inches. Both values must be positive numbers, and rainfall should be greater than or equal to losses for meaningful results.
Q1: What factors affect runoff losses?
A: Soil type, vegetation cover, land slope, rainfall intensity, and antecedent moisture conditions all significantly impact runoff losses.
Q2: How accurate is this simple runoff calculation?
A: While useful for basic estimation, more complex models (like SCS Curve Number method) provide better accuracy by accounting for additional factors.
Q3: What are typical loss values?
A: Losses vary widely but typically range from 0.2-0.8 inches for moderate rainfall events, depending on soil conditions and land use.
Q4: When is this calculation most applicable?
A: This approach works best for preliminary estimates and educational purposes rather than engineering design where more sophisticated methods are needed.
Q5: How does urbanization affect runoff?
A: Urbanization typically increases runoff by reducing infiltration through impervious surfaces like roads and buildings.