Slope of Ground Surface Given Peak Rate of Runoff Calculator

Burkli Zeigler Formula:

\[ Slope\ of\ the\ ground = \left( \frac{Peak\ Rate\ of\ Runoff \times 455}{Intensity\ of\ Rainfall \times Runoff\ Coefficient \times \sqrt{Drainage\ Area}} \right)^2 \]

Peak Rate of Runoff (QBZ):

m³/s

Intensity of Rainfall (IBZ):

m/s

Runoff Coefficient (K'):

Drainage Area (AD):

m²

Slope of the Ground (So):

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1. What is the Burkli Zeigler Formula?

The Burkli Zeigler formula is used to calculate the slope of ground surface based on peak rate of runoff, rainfall intensity, runoff coefficient, and drainage area. It's an important equation in hydrological engineering for drainage system design.

2. How Does the Calculator Work?

The calculator uses the Burkli Zeigler formula:

\[ Slope\ of\ the\ ground = \left( \frac{QBZ \times 455}{IBZ \times K' \times \sqrt{AD}} \right)^2 \]

Where:

\( QBZ \) — Peak Rate of Runoff (m³/s)
\( IBZ \) — Intensity of Rainfall (m/s)
\( K' \) — Runoff Coefficient (dimensionless)
\( AD \) — Drainage Area (m²)
455 — Empirical constant in the formula

Explanation: The formula calculates ground slope by considering the relationship between runoff characteristics and drainage area geometry.

3. Importance of Slope Calculation

Details: Accurate slope calculation is crucial for designing effective drainage systems, predicting water flow patterns, and preventing flooding in urban and rural areas.

4. Using the Calculator

Tips: Enter peak runoff rate in m³/s, rainfall intensity in m/s, runoff coefficient (0-1), and drainage area in m². All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for runoff coefficient?
A: Runoff coefficient typically ranges from 0.3-0.95, with higher values for impervious surfaces like concrete and lower values for permeable surfaces like grass.

Q2: How is rainfall intensity measured?
A: Rainfall intensity is usually measured in mm/hr but should be converted to m/s for this calculation (1 mm/hr = 2.77778×10⁻⁷ m/s).

Q3: What factors affect the peak rate of runoff?
A: Peak runoff rate is influenced by rainfall intensity, catchment area, surface roughness, slope, and soil permeability.

Q4: When is this formula most applicable?
A: The Burkli Zeigler formula is particularly useful for small to medium-sized urban drainage systems and watershed management planning.

Q5: Are there limitations to this formula?
A: The formula assumes uniform rainfall distribution and may be less accurate for very large or complex drainage areas with heterogeneous surface conditions.