Peak Discharge from Drainage Basin Runoff Formula |
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| \( Q \;=\; c \cdot i \cdot A \) | ||
| Symbol | English | Metric |
| \( Q \) = Vapor Mass Velocity of Tray Type Tower | \(cfm\) | - |
| \( c \) = Rational Method Runoff Coefficient | \(dimensionless\) | - |
| \( i \) = Rainfall Intensity | \(in\;/\;hr\) | - |
| \( A \) = Drainage Area | \(acre\) | - |
Peak discharge from drainage basin runoff is the maximum flow rate of water passing through a specific point in a drainage system (like a river or stream) after a rainfall or snowmelt event. It represents the highest volume of water per unit of time occurring at the outlet of a drainage basin or watershed during or after a storm. Understanding peak discharge is used in hydrology for flood forecasting, designing stormwater management systems, and flood prevention strategies.
Rational Method Runoff Coefficient |
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| Ground Cover | Runoff Coefficient |
| Asphault Streets | 0.7 - 0.95 |
| Brick Streets | 0.7 - 0.85 |
| Buisness Areas | 0.5 - 0.95 |
| Concrete Streets | 0.7 - 0.95 |
| Cultivated Land | 0.08 - 0.41 |
| Forest | 0.05 - 0.25 |
| Industrial Area | 0.5 - 0.9 |
| Lawn | 0.05 - 0.35 |
| Meadow | 0.1 - 0.5 |
| Parks, Cemeteries | 0.1 - 0.25 |
| Pasture | 0.12 - 0.62 |
| Residential Area | 0.3 - 0.75 |
| Roofs | 0.75 - 0.95 |
| Unimproved Area | 0.1 - 0.3 |
Key Points Influence Peak Discharge
Rainfall Intensity and Duration - More intense and prolonged rainfall will result in a higher peak discharge.
Basin Size and Shape - Larger and steeper basins tend to have a quicker and higher peak discharge due to the faster runoff.
Soil Type and Vegetation - Soils that absorb water slowly, along with minimal vegetation, lead to higher runoff and peak discharge.
Land Use and Urbanization - Urbanized areas with impervious surfaces (like concrete) prevent water infiltration, leading to quicker runoff and higher peak discharge.
Antecedent Moisture Conditions - Wet soils prior to rainfall will absorb less water, increasing the runoff and peak discharge.
