What can significantly vary from place to place along a stream channel?

Flow velocity is influenced by several factors along a stream channel, leading to significant variation from one location to another. The velocity of a stream depends on the channel shape, slope, and the presence of obstacles such as rocks or vegetation. For instance, where the channel narrows, the flow is often faster due to conservation of mass, while broader sections may slow the current.

Additionally, the gradient of the stream and changes in elevation can also affect flow velocity. Steeper gradients tend to result in higher velocities, while flatter areas can slow down the water. As a result, measurements of flow velocity can show considerable differences at various points, reflecting the dynamic nature of stream systems in response to both natural and anthropogenic changes.

While stream gradient, wetted perimeter, and discharge are important parameters in determining stream characteristics, they may not demonstrate the same level of variability in the way that flow velocity does, which can fluctuate dramatically based on local conditions within a stream channel.