THE BEHAVIOR OF STRATIFIED POOLS IN THE WIMMERA RIVER, AUSTRALIA

Numerous inland Australian streams contain density-stratified or salin e pools, which are usually located on channel bends. Saline pools cons ist of a layer of saline water underlying a layer of fresh water. Sali ne pools generally form as a result of saline groundwater seeping into the stream and collecting in scour depressions during periods of low flow. Inflows of saline river water can also collect in scour depressi ons. Field and laboratory investigations of saline pool mixing by over flowing fresh water reveal that mixing depends on a balance between in terfacial shear and buoyancy forces acting on a thin dense layer flowi ng up the downstream slope of the scour depression, and on the bend sh arpness. Convection associated with surface cooling also causes mixing . A model for saline pools formed by groundwater inflows and mixed by fresh overflows is proposed and applied to several saline pools in the Wimmera River.