Lower course of a river - Info sheet

The lower course of a river is characterised by a significant increase in the volume of water, resulting in a deep and wide river channel that meanders through the flat surrounding land. This part of the river is where deposition predominantly occurs due to the lowest energy levels in the water flow. Notable geographical features such as deltas, floodplains, and oxbow lakes are commonly found near the mouth of large rivers. These features are a testament to the dynamic nature of rivers in their final stages, with the largest bends or meanders forming in the lower course. Students are encouraged to engage with educational resources, such as diagrams, that illustrate how an oxbow lake is created, and to discuss their understanding with peers.

In the lower course, rivers are more powerful and carry a higher volume of water, which contributes to increased lateral erosion. The river's channel becomes broader and deeper as a result, and with less friction to slow it down, the water flows more swiftly. The erosion process leads to the formation of large meanders that snake across the landscape. Over time, these meanders can become more pronounced until the river eventually cuts through the neck of a meander. This process results in a straighter river channel and leaves behind an isolated meander loop, known as an oxbow lake. Understanding these processes helps to explain the distinctive features that develop along the upper, middle, and lower courses of a river.