1. What is Fanning's Formula?

Fanning's Formula is an empirical equation used in hydrology to estimate the catchment area based on flood discharge data. It provides a mathematical relationship between flood discharge, Fanning's constant, and the resulting catchment area.

2. How Does the Calculator Work?

The calculator uses Fanning's Formula:

Where:

• \( A_{km} \) — Catchment Area for Flood Discharge (km²)
• \( Q_F \) — Flood Discharge by Fanning's Formula (m³/s)
• \( C_F \) — Fanning's Constant (dimensionless)

Explanation: The formula calculates the catchment area by taking the ratio of flood discharge to Fanning's constant and raising it to the power of 6/5.

3. Importance of Catchment Area Calculation

Details: Accurate catchment area estimation is crucial for flood prediction, water resource management, and infrastructure planning in hydrological studies.

4. Using the Calculator

Tips: Enter flood discharge in m³/s and Fanning's constant value. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is Fanning's Constant?
A: Fanning's Constant is an empirical value used in flood estimation formulas, typically adjusted for specific regional conditions, especially for American catchment areas.

Q2: What units are used in this calculation?
A: Flood discharge is measured in cubic meters per second (m³/s), and the resulting catchment area is in square kilometers (km²).

Q3: When should Fanning's Formula be used?
A: This formula is particularly useful for flood estimation in American catchment areas and regions where Fanning's constant has been calibrated.

Q4: Are there limitations to this formula?
A: The accuracy depends on the appropriate selection of Fanning's constant for the specific geographical region and hydrological conditions.

Q5: Can this formula be used for all catchment areas?
A: While generally applicable, the formula works best for regions where Fanning's constant has been properly calibrated and validated.