Isbash Equation

\[ D_{50} = \frac{V^2}{2 \times g \times C^2 \times (S - 1)} \]

Where:

• \( D_{50} \) = Average diameter of 50% of the spherical rocks for the rip rap in meters
• \( V \) = Average channel velocity in meters per second
• \( g \) = Acceleration due to gravity (\( 9.806 \, \text{m/s}^2 \))
• \( C \) = Isbash constant (0.86 for highly turbulent flow, 1.20 for low turbulence flow)
• \( S \) = Specific gravity of the rock (ranges from 2.50 to 3.00)