1. What is Time of Concentration?

The Time of Concentration (T_c) is the time required for water to flow from the most hydraulically distant point in a watershed to the outlet. It's a key parameter in hydrologic analysis and stormwater management.

2. How Does the Calculator Work?

The calculator uses the Time of Concentration equation:

Where:

• \( T_c \) — Time of concentration (minutes)
• \( L \) — Length of flow path (feet)
• \( S \) — Slope of flow path (decimal)

Explanation: The equation accounts for the relationship between flow length, slope, and the time it takes for water to reach the outlet.

3. Importance of Time of Concentration

Details: Accurate T_c calculation is crucial for determining peak discharge rates, designing drainage systems, and flood forecasting.

4. Using the Calculator

Tips: Enter flow length in feet and slope as a decimal (e.g., 0.01 for 1% slope). All values must be valid (length > 0, slope > 0).

5. Frequently Asked Questions (FAQ)

Q1: What are typical Time of Concentration values?
A: T_c varies widely depending on watershed characteristics, typically ranging from minutes for small urban areas to hours for large rural watersheds.

Q2: How does slope affect Time of Concentration?
A: Steeper slopes result in shorter times of concentration as water flows faster downhill.

Q3: What are the limitations of this equation?
A: This empirical equation works best for overland flow in small watersheds. Different methods may be needed for channel flow or complex terrain.

Q4: How is length of flow path measured?
A: Measure from the most hydraulically distant point in the watershed to the outlet, following the flow path.

Q5: Can this be used for all watershed types?
A: This equation is most appropriate for natural, rural watersheds. Urban areas may require different calculation methods.