GEOLOGY

Detailed explanation-1: -Stream Velocity Depends on the Shape and Size of the Channel Water flow in a stream is primarily related to the stream’s gradient, but it is also controlled by the geometry of the stream channel. As shown in Figure 14.15, water flow velocity decreases due to friction along the stream bed.

Detailed explanation-2: -If the slope is too gentle and velocity is too slow to transport the sediments being supplied by weathering and erosion, the sediments will pile up. This increases the gradient which causes the water to flow faster which increases erosion and transport, which then reduces the gradient.

Detailed explanation-3: -The factors that determine a stream’s velocity are gradient (slope of the stream channel), shape, size, and roughness of the channel, and the stream’s discharge (amount of water passing a given point per unit of time, frequently measured in cubic feet per second).

Detailed explanation-4: -For a 10 mm gravel grain, the velocity is 105 cm/s to be eroded from the bed but only 80 cm/s to remain in suspension. On the other hand, a 0.01 mm silt particle only needs a velocity of 0.1 centimetres per second (cm/s) to remain in suspension, but requires 60 cm/s to be eroded.