Meander and Oxbow Lake Formation
Understanding how meanders form is actually quite straightforward once you grasp the energy differences. On the outside bend, fast-flowing water packs more energy, leading to intense erosion through hydraulic action and abrasion. This creates the steep river cliff and deeper water.
The inside bend tells a completely different story. Here, slow-moving water lacks energy, so deposition dominates. Sediment gets dumped, forming the gently sloping river beach in shallow water. This continuous process of "erode outside, deposit inside" gradually creates the meander's distinctive shape.
Oxbow lakes form when meanders become too extreme for their own good. Continuous erosion narrows the "neck" of the meander until high flow periods allow the river to cut straight through, creating a new direct channel.
Remember: Oxbow lakes are temporary features - they'll eventually dry up and disappear from the landscape.
Once the river finds this shortcut, all the energy focuses on the new channel. The old meander gets cut off as deposition blocks both its entrance and exit. What's left behind is a curved oxbow lake that will gradually fill with sediment and vegetation over time.