1. What is the Area of Catchment Formula?

The Area of Catchment formula calculates the land area where all water flows to a single stream, river, lake or ocean. It uses peak drainage discharge, runoff coefficient, and critical rainfall intensity to determine the catchment area.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( A_c \) — Area of Catchment (m²)
• \( Q_R \) — Peak Drainage Discharge by Rational Formula (m³/s)
• \( C_r \) — Runoff Coefficient (dimensionless)
• \( P_c \) — Critical Rainfall Intensity (cm/h)

Explanation: The formula calculates the catchment area based on the relationship between peak discharge, runoff characteristics, and rainfall intensity.

3. Importance of Catchment Area Calculation

Details: Accurate catchment area calculation is crucial for hydrological modeling, flood prediction, water resource management, and urban drainage system design.

4. Using the Calculator

Tips: Enter peak drainage discharge in m³/s, runoff coefficient (0-1), and critical rainfall intensity in cm/h. All values must be positive numbers.

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 rather than being absorbed by the ground.

Q2: How is critical rainfall intensity determined?
A: Critical rainfall intensity is the precipitation rate at which surface runoff begins, typically determined through hydrological analysis of rainfall data.

Q3: What factors affect the runoff coefficient?
A: Surface type, soil composition, slope, land use, and vegetation cover all influence the runoff coefficient value.

Q4: When is this formula most applicable?
A: This formula is particularly useful for small to medium-sized catchments in urban and rural hydrological studies.

Q5: Are there limitations to this calculation?
A: The formula assumes uniform rainfall distribution and may be less accurate for very large catchments or complex terrain.