What generally happens when the wetted perimeter is higher in comparison to its volume?

When the wetted perimeter is higher in comparison to the volume of water, it generally indicates a wider or shallower flow of water, which leads to increased friction with the channel boundaries. This friction results in a reduction of flow velocity.

A higher wetted perimeter means that more of the channel's surface is in contact with the water, creating more resistance to flow. In shallow, wide channels, the flow tends to be slower because the energy is dissipated over a larger surface area, leading to a decreased velocity of the water as it moves through the channel. Additionally, a higher wetted perimeter often corresponds with less efficient flow conditions, contributing to this decrease in velocity.

In contrast, changes in discharge— the volume of water flowing per second—would be more related to the overall cross-sectional area and flow conditions rather than simply the relationship between wetted perimeter and volume. Thus, a higher wetted perimeter, combined with volume considerations, significantly influences flow dynamics by reducing velocity.