Numerical Investigation of Wind Driven Circulation and Horizontal Dispersion in the Surface Layer of a Re-flooded Shallow Lake

Abstract

The re-flooded lakes with unique natural and cultural values that are under threat from anthropogenic pressure, consist a very important section of fresh water resources management in the Mediterranean. Lake Karla, positioned in the eastern part of Thessaly (Greece), is an example of a lake ecosystem, which was dried in the 60s to provide additional agricultural land; its restoration was launched in 2000 under the 3rd Community Support Framework. The object of the present paper is the study of the effect of the inflows, the wind action and the Coriolis action on the water circulation and the horizontal dispersion of the lake, using a three-dimensional hydrodynamic model. A number of wind directions have been tested upon the lake’s circulation, while in addition to winds other parameters, like inflow and Coriolis force, have been accounted for. Conservative computational tracers were used to assess the rate of horizontal dispersion from various locations in Lake Karla. The simulations indicated that in the coastal strip, the direction of the current corresponded to the wind direction. The horizontal dispersion rate is higher in the central region of the lake and it is not influenced by the presence of the inflow from Pinios River and the Coriolis action. The research in this paper will be useful in determining the horizontal transport of waterborne materials in the lake body which plays a major role in determining its biochemical status.