1. What is Lacey's Formula?

Lacey's Formula is used to estimate runoff depth in inches based on rainfall depth, monsoon duration factor, and catchment characteristics. It provides a practical approach for hydrological calculations in various engineering applications.

2. How Does the Calculator Work?

The calculator uses Lacey's Formula:

Where:

• \( RLI \) — Runoff Depth in Inches
• \( RPI \) — Rainfall Depth in Inches
• \( Fm \) — Monsoon Duration Factor
• \( S \) — Catchment Factor

Explanation: The formula accounts for the relationship between rainfall intensity, monsoon duration, and catchment characteristics to estimate surface runoff.

3. Importance of Runoff Calculation

Details: Accurate runoff estimation is crucial for designing drainage systems, flood control measures, water resource management, and environmental impact assessments.

4. Using the Calculator

Tips: Enter rainfall depth in inches, monsoon duration factor, and catchment factor. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for monsoon duration factor?
A: The monsoon duration factor typically ranges from 0.5 to 2.0, depending on regional climatic conditions and monsoon intensity.

Q2: How is catchment factor determined?
A: Catchment factor depends on topography, shape, size, soil type, and land use characteristics of the watershed area.

Q3: What are typical runoff values?
A: Runoff values vary significantly based on rainfall intensity, soil conditions, and land cover, typically ranging from 10% to 90% of rainfall depth.

Q4: When is Lacey's Formula most applicable?
A: Lacey's Formula is particularly useful for monsoon regions and areas with well-defined rainfall patterns and catchment characteristics.

Q5: Are there limitations to this formula?
A: The formula may be less accurate for extreme rainfall events, highly urbanized areas, or regions with complex hydrological conditions.