Regional Constant Given Peak Discharge Calculator

Formula Used:

\[ Regional\ Constant = \frac{Peak\ Discharge \times Basin\ Lag}{2.78 \times Catchment\ Area} \]

Regional Constant (Cr):

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1. What is the Regional Constant?

The Regional Constant represents watershed slope and storage effect in hydrological calculations. It is a dimensionless parameter used to characterize the relationship between peak discharge, basin lag time, and catchment area in a specific watershed region.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Regional\ Constant = \frac{Peak\ Discharge \times Basin\ Lag}{2.78 \times Catchment\ Area} \]

Where:

\( Peak\ Discharge \) — Maximum volume flow rate (m³/s)
\( Basin\ Lag \) — Elapsed time between rainfall centroids (hours)
\( Catchment\ Area \) — Area where water flows to a single stream (m²)
2.78 — Conversion factor

Explanation: This formula calculates the regional constant that represents the combined effect of watershed characteristics on the relationship between rainfall and runoff.

3. Importance of Regional Constant Calculation

Details: Accurate calculation of the regional constant is crucial for hydrological modeling, flood prediction, watershed management, and designing hydraulic structures. It helps in understanding the storage and routing characteristics of a watershed.

4. Using the Calculator

Tips: Enter peak discharge in cubic meters per second, basin lag in hours, and catchment area in square meters. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What does the Regional Constant represent?
A: The Regional Constant represents the combined effect of watershed slope and storage characteristics on the relationship between rainfall input and runoff output.

Q2: Why is 2.78 used in the formula?
A: The value 2.78 is a conversion factor that accounts for unit conversions between discharge (m³/s), time (hours), and area (m²).

Q3: What are typical values for the Regional Constant?
A: Typical values range from 0.1 to 10, depending on watershed characteristics. Steeper watersheds with less storage tend to have higher values.

Q4: How does basin lag affect the Regional Constant?
A: Longer basin lag times generally result in higher regional constant values, indicating greater storage and slower response in the watershed.

Q5: Can this formula be used for all watershed types?
A: While the formula provides a general approach, specific watershed characteristics may require regional calibration or modified approaches for optimal accuracy.