What is a meander?

A meander refers to a bend or curve in a river, typically located in the middle course where the river's flow is slower, allowing it to carve out these distinctive shapes. The formation of meanders occurs due to the complex interactions between the flow of water and the landscape, as the river erodes the outer banks of the bend while depositing sediment on the inner banks. This process is a natural part of river dynamics and is indicative of a river that has reached maturity, where it has enough energy to start shaping its own path more significantly.

In contrast, the other options describe different river phenomena. A sudden rise in river water levels refers to flooding, which is a different aspect of river behavior. The beginning point of a river's journey is known as the source, which is distinct from what happens in the river's course. River bank erosion is a process that can contribute to meandering but does not define what a meander itself is.