Describe what occurs as a river approaches base level.?

Question

Describe what occurs as a river approaches base level.?

Answer 1

The base level of a river or stream is the lowest point to which it can flow, often referred to as the 'mouth' of the river.

A low base level is a prerequisite for the formation of karst topography, a network of sinkholes and caverns that can develop as slightly acidic groundwater enlarges joints (by solution) in limestone rock. Often this network of underground drainage feeds back to surface drainage along the edges of larger rivers, which are the effective base level.

When the source of a stream is very high relative to its base level (high stream gradient), erosion proceeds rapidly due to the energy of the rapidly moving water and the topography becomes rugged, and it is considered a young stream (geologically speaking). When erosion has acted for a long geologic time, wearing down the high points and making a small difference between the source and the base level of a stream (low stream gradient), then the stream is called mature. Mature stream valleys have gentle slopes, rounded higher points and meandering courses.