Peak Rate of Runoff from Nawab Jung Bahadur Formula Calculator

Nawab Jung Bahadur Formula:

\[ Q_{NJB} = C_2 \times (A_{km})^{0.93 - \frac{1}{14} \times \log_{10}(A_{km})} \]

Peak Rate of Runoff (Q_NJB):

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1. What is the Nawab Jung Bahadur Formula?

The Nawab Jung Bahadur Formula estimates the peak rate of stormwater runoff using catchment area and a coefficient parameter. It provides a mathematical approach to determine the maximum flow rate during storm events for hydrological analysis and engineering design.

2. How Does the Calculator Work?

The calculator uses the Nawab Jung Bahadur formula:

\[ Q_{NJB} = C_2 \times (A_{km})^{0.93 - \frac{1}{14} \times \log_{10}(A_{km})} \]

Where:

\( Q_{NJB} \) — Peak rate of runoff (m³/s)
\( C_2 \) — Coefficient (dimensionless)
\( A_{km} \) — Catchment area (km²)
\( \log_{10} \) — Base-10 logarithm function

Explanation: The formula incorporates a logarithmic relationship between catchment area and runoff rate, with the exponent varying based on the logarithm of the area.

3. Importance of Peak Runoff Calculation

Details: Accurate peak runoff estimation is crucial for designing drainage systems, flood control structures, and hydraulic infrastructure. It helps in determining appropriate channel sizes, culvert capacities, and stormwater management systems.

4. Using the Calculator

Tips: Enter the coefficient value and catchment area in square kilometers. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What factors influence the coefficient value?
A: The coefficient depends on various factors including soil type, land use, vegetation cover, slope, and rainfall intensity characteristics of the catchment area.

Q2: How accurate is the Nawab Jung Bahadur formula?
A: The accuracy depends on proper coefficient selection and catchment characteristics. It works well for medium-sized catchments but may require calibration for specific regional conditions.

Q3: What is the typical range of coefficient values?
A: Coefficient values typically range from 0.1 to 0.8, with higher values for impervious surfaces and lower values for pervious, vegetated areas.

Q4: Can this formula be used for urban areas?
A: Yes, but the coefficient should be adjusted to account for higher runoff due to impervious surfaces in urban environments.

Q5: What are the limitations of this formula?
A: The formula may not accurately represent extreme rainfall events, very small or very large catchments, or areas with complex topography and drainage patterns.