1. What is the Dredge Formula?

The Dredge Formula is used to calculate the peak rate of runoff from a catchment area. It provides an estimate of the maximum discharge rate during runoff events, which is crucial for drainage system design and flood management.

2. How Does the Calculator Work?

The calculator uses the Dredge Formula:

Where:

• \( Q_d \) — Peak rate of runoff (m³/s)
• \( A_{km} \) — Catchment area (km²)
• \( L \) — Length of drain (meters)

Explanation: The formula calculates the maximum runoff rate based on the catchment area and the length of the drainage system, with the constant 19.6 derived from empirical data.

3. Importance of Peak Runoff Calculation

Details: Accurate peak runoff estimation is essential for designing effective drainage systems, preventing flooding, and ensuring proper water management in urban and rural areas.

4. Using the Calculator

Tips: Enter the catchment area in square kilometers and the length of the drain in meters. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of Q_d values?
A: Q_d values vary widely depending on catchment size and drain length, typically ranging from a few m³/s to several hundred m³/s for larger systems.

Q2: How accurate is the Dredge Formula?
A: The formula provides a reasonable estimate but should be used with caution as it doesn't account for all factors like rainfall intensity, soil type, or slope.

Q3: When should this formula be used?
A: It's commonly used for preliminary drainage design and flood estimation in various engineering applications.

Q4: Are there limitations to this formula?
A: Yes, it doesn't consider temporal variations in rainfall, infiltration rates, or complex topography of the catchment area.

Q5: Can this formula be used for all types of catchments?
A: While generally applicable, it works best for moderately sized catchments with relatively uniform characteristics.