Stream Velocity (V) = [K * (D)^0.5] / (n)
Where:
- V = Stream Velocity in meters per second (m/s)
- K = Empirical coefficient related to channel characteristics and sediment properties
- D = Boulder diameter in meters (m)
- n = Manning's roughness coefficient
For small boulders, we can consider a boulder diameter (D) of approximately 0.5 meters. The empirical coefficient (K) can vary depending on the specific channel conditions, sediment properties, and flow characteristics. A commonly used value for K is around 2.5.
Manning's roughness coefficient (n) represents the resistance to flow caused by the channel bed and its irregularities. For a natural stream with some vegetation and obstructions, a typical value for n could be around 0.035.
Plugging these values into the formula:
V = [2.5 * (0.5)^0.5] / 0.035
V ≈ 1.18 meters per second
Therefore, a stream velocity of approximately 1.18 meters per second would be required to carry the smallest boulders with a diameter of 0.5 meters. It's important to note that these calculations provide a general estimate, and actual stream velocities needed to transport boulders may vary depending on the specific conditions and characteristics of the stream or river.
