The rotation of the Earth is encouraging the mixing of water in Italy's picturesque Lake Garda, according to the findings of a new study.
Ventilation and water mixing are essential for lake ecosystems. New research, published this week in the journal Scientific Reports, suggests the rotation of the Earth aids water mixing in long, narrow lakes like Lake Garda.
Scientists in the Netherlands and Italy worked together to develop a series of sophisticated hydrodynamic models. The simulations of water movement in Lake Garda revealed a unique interaction between local wind patterns and the planet's rotational forces.
In the spring and early summer, as ice melts and sinks to the bottom, and as the top layers of the lake are warmed more quickly, lakes become thermally stratified, preventing the even distribution of oxygen and nutrients.
Winds and waves fuel mixing, which helps distribute the nutrients and oxygen that underpin freshwater food chains.
"According to our study, when the wind blows along Lake Garda's main axis, the Earth's rotation causes a secondary circulation which displaces the water laterally, from one coast to the other," Marina Amadori, an environmental engineer and researcher at the University of Trento in Italy, said in a news release.
The phenomenon creates a temperature difference between Lake Garda's eastern and western shores, which encourages the water column to turn over.
"In detail, in the case of Foehn winds, cold water surfaces along the eastern side of the lake, upwelling, and warmer water moves down along the western side, downwelling," said Sebastiano Piccolroaz, researcher at Utrecht University in the Netherlands.
"Between February and April in particular, when the lake water temperature is at its lowest, the vertical movement can reach even the bottom of the lake, that is at a depth of 350m. We did not expect to observe in Lake Garda an event that is typical of the coastal areas of oceans and large lakes," he said.
