Drainage Area Given Runoff Rate Of Rainwater From Bridge During Rainstorm Calculator

Formula Used:

\[ A_{catchment} = \frac{q_p}{1.00083 \times C_r \times I} \]

Peak Rate of Runoff (q_p):

m³/s

Runoff Coefficient (C_r):

(dimensionless)

Intensity of Rainfall (I):

m/s

Catchment Area (A_catchment):

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1. What is the Drainage Area Calculation?

The drainage area calculation determines the total catchment area from where rainwater runoff is collected, specifically for bridge drainage systems during rainstorms. This is essential for proper water management and flood prevention in infrastructure design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ A_{catchment} = \frac{q_p}{1.00083 \times C_r \times I} \]

Where:

\( A_{catchment} \) — Catchment Area for Rainstorm (m²)
\( q_p \) — Peak Rate of Runoff (m³/s)
\( C_r \) — Runoff Coefficient (dimensionless)
\( I \) — Intensity of Rainfall (m/s)

Explanation: The formula calculates the drainage area required to handle the peak runoff rate based on rainfall intensity and surface runoff characteristics.

3. Importance of Drainage Area Calculation

Details: Accurate drainage area calculation is crucial for designing effective bridge drainage systems, preventing water accumulation, and ensuring structural integrity during heavy rainfall events.

4. Using the Calculator

Tips: Enter peak runoff rate in m³/s, runoff coefficient (0-1), and rainfall intensity in m/s. All values must be positive and valid for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is the runoff coefficient?
A: The runoff coefficient is a dimensionless factor that represents the fraction of rainfall that becomes surface runoff, depending on surface type and conditions.

Q2: How is rainfall intensity measured?
A: Rainfall intensity is typically measured in meters per second (m/s) or millimeters per hour (mm/h), representing the rate of rainfall over a specific period.

Q3: Why is the constant 1.00083 used?
A: This constant accounts for unit conversions and specific hydrological factors in the drainage calculation formula.

Q4: What factors affect the runoff coefficient?
A: Surface material, slope, vegetation cover, soil type, and antecedent moisture conditions all influence the runoff coefficient value.

Q5: How accurate is this calculation?
A: While providing a good estimate, actual conditions may vary due to local topography, drainage system efficiency, and rainfall distribution patterns.