Plunge basin
Appearance
A plunge basin, in hydrology, is a stretch of a river or creek in which the water depth is above average and the stream velocity is quite low. Such pools can be important for juvenile fish habitat, especially where many stream reaches attain high summer temperatures and very low flow dry season characteristics. A stream pool may be bedded in sediment or armoured with gravels; in some cases the pool formations may have been formed as basins in bedrock materials. This portion of a stream often provides specialized aquatic habitat for organisms that have difficulty feeding or navigating in swifter reaches of the stream.