Riffle

A riffle is a feature of a river or stream where the water flows over a series of small, often rocky or gravelly, ridges or bumps. These create rapid, turbulent flows and churning water, which help to aerate the water and break up sediments. Riffles are important for ecological health because they provide oxygen-rich environments for aquatic life and influence nutrient cycling. They can form naturally through erosion or be created artificially in water management projects. Essentially, a riffle is a shallow, fast-moving section that enhances the river's health and biodiversity.