1. What is the Catchment Area Formula?

The formula calculates the area of catchment based on peak discharge, basin lag, and regional constant. It's derived from Snyder's unit hydrograph method for watershed analysis and flood prediction.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( A \) — Area of Catchment (km²)
• \( Q_p \) — Peak Discharge (m³/s)
• \( t_p \) — Basin Lag (hours)
• \( C_p \) — Regional Constant (dimensionless)

Explanation: The formula relates catchment area to peak discharge, basin lag time, and a regional constant that accounts for watershed characteristics.

3. Importance of Catchment Area Calculation

Details: Accurate catchment area calculation is essential for flood forecasting, water resource management, and hydraulic structure design.

4. Using the Calculator

Tips: Enter peak discharge in m³/s, basin lag in hours, and regional constant. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is basin lag in hydrology?
A: Basin lag is the time difference between the centroid of rainfall excess and the centroid of the resulting runoff hydrograph.

Q2: How is regional constant determined?
A: Regional constant is derived from historical data and varies based on watershed characteristics like slope, soil type, and land use.

Q3: What are typical values for regional constant?
A: Cp values typically range from 0.4 to 0.8, with higher values indicating faster watershed response to rainfall.

Q4: When is this formula most applicable?
A: This formula is most applicable for medium to large watersheds with relatively uniform characteristics.

Q5: Are there limitations to this approach?
A: The formula assumes linear watershed response and may not be accurate for highly urbanized or extremely heterogeneous watersheds.