1. What is Rainwater Collection Calculation?

Rainwater collection calculation estimates the volume of rainwater that can be harvested from a roof surface using the formula RW = A × R × C, where A is the catchment area, R is the rainfall amount, and C is the runoff coefficient.

2. How Does the Calculator Work?

The calculator uses the rainwater collection formula:

Where:

• \( A \) — Catchment area (m²)
• \( R \) — Rainfall amount (m)
• \( C \) — Runoff coefficient (unitless)

Explanation: The equation calculates the volume of rainwater that can be collected from a roof surface, accounting for losses due to evaporation, absorption, and other factors through the runoff coefficient.

3. Importance of Rainwater Collection

Details: Accurate rainwater collection calculation is crucial for sustainable water management, irrigation planning, and designing rainwater harvesting systems for residential and commercial buildings.

4. Using the Calculator

Tips: Enter catchment area in square meters, rainfall amount in meters, and runoff coefficient (typically between 0.7-0.9 for roof surfaces). All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical runoff coefficient for roof surfaces?
A: For most roof materials, the runoff coefficient ranges from 0.7 to 0.9, with smoother surfaces having higher coefficients.

Q2: How do I convert rainfall from mm to meters?
A: Divide the rainfall in mm by 1000 to get meters (e.g., 50 mm = 0.05 m).

Q3: What factors affect the runoff coefficient?
A: Roof material, slope, surface roughness, and rainfall intensity all influence the runoff coefficient value.

Q4: Can this calculation be used for large-scale systems?
A: Yes, the same formula applies for both small residential and large commercial rainwater harvesting systems.

Q5: How accurate is this calculation?
A: The calculation provides a good estimate, but actual collection may vary due to factors like first-flush diversion, evaporation, and system efficiency.