Wetted perimeter

The wetted perimeter is the part of the edge of a river or stream that gets wet. Imagine putting your foot in a stream. The part of your foot that is touching the water is the wetted perimeter. It's important because it affects how much water is able to flow through the stream or river. If the wetted perimeter is larger, it means that the water is more spread out and there is less space for the water to flow, which slows down the flow of the river or stream. On the other hand, if the wetted perimeter is smaller, the water is more concentrated and can flow faster. Scientists and engineers use measurements of the wetted perimeter to understand how rivers and streams work and how they can design structures like bridges and dams to withstand the flow of water.