Look a little closer
A river on flat ground does not meander merely because water lazily chooses an easy path. A tiny bend changes where water moves fastest and where sediment is removed, and those differences can feed back to enlarge the curve.
Even a channel that appears straight has uneven banks, bed material, vegetation and small flow disturbances. These variations can nudge the current toward one side. Once a bend exists, the fastest part of the flow tends to shift toward the outer bank.
Higher velocity and shear stress erode the outside of the bend. Slower water on the inside drops sand and gravel, building a point bar. The outer bank retreats while the inner bank advances, so the bend migrates sideways and often becomes more pronounced.
Water also follows a three-dimensional, corkscrew-like circulation around bends. This motion helps move some eroded sediment toward the inner side. Discharge, slope, sediment size and bank strength all influence the final shape and migration rate.
As a loop grows, two parts of the channel may approach one another. A flood can cut a shorter route across the narrow neck. When the main flow adopts that shortcut, the abandoned curve becomes an oxbow lake that may later fill with sediment and vegetation.
A meander is therefore a moving landform, not a fixed decorative pattern. Erosion on the outside and deposition on the inside reinforce one another while the river slowly rearranges its path across the floodplain.
