Typical near surface layer current patterns in Lake Geneva's man basin (Grand Lac)
The Lake Geneva current field is controlled by a variable wind field and thermal stratification. Typical current patterns in the Grand Lac, which is oriented roughly in the East-West direction, were determined under typical wind conditions and thermal stratifications using the DELFT3D-FLOW hydrodynamic model. The model solves the Reynolds-Averaged Navier-Stokes equations, combined with a k-ε turbulence closure in z coordinate system in the vertical axis. Typical wind patterns over the lake were identified using the k-means clustering method. The response of the near surface lake current circulations to the typical wind patterns and stratification are determined. For a given wind speed, modeling results revealed stronger current velocity for the near surface layer in stratified season (summer), compared with the non-stratified season (winter). A counter-clockwise circulation pattern in the central part of the Grand Lac was identified under large scale north-easterly winds (Bise), which occurs frequently. For large scale south-westerly winds (Vent), another frequent wind, a long-fetch (up to 30 km) leads to a clockwise circulation pattern in the central part of the main basin during non-stratified seasons. Strong eastward currents are observed in the Grand Lac. In the eastern part of the Grand Lac at the mouth of the Rhone River, a small counter-clockwise gyre may occur frequently under both Bise and Vent events.
Record created on 2015-01-06, modified on 2016-08-09