Exchange Processes Between Littoral And Pelagic Waters In A Stratified Lake

Abstract

The physical processes responsible for the exchange of water and particles
between lake boundaries (littoral) and interior (pelagic) are investigated using field data and
the three-dimensional hydrodynamic Estuary and Lake Computer Model (ELCOM) in Lake
Kinneret, Israel. The field data revealed large-scale metalimnion oscillations with amplitudes
up to 10 m in response to westerly diurnal winds and the existence of a well-defined
suspended particle intrusion into the metalimnion of the lake. The changes in the thermal
structure explained the observed vertical and horizontal movements of the suspended particle
intrusion. The horizontal advective transport via the metalimnion, associated with the
velocities induced by the basin-scale mode-two Poincaré wave, controlled the exchange
between lake boundaries and interior on daily timescales. Detailed comparison of simulation
results with field data revealed that the model captured the lake hydrodynamics for time
scales from hours to days. The numerical simulation showed bottom shear velocities capable
of resuspension and so a source of the observed suspended particle intrusion. Together, field
data and numerical modelling clarified the flux path of water and particles between littoral
and pelagic waters in the lake and demonstrated the importance of a proper characterization
of the processes involved required for modelling and management of water quality resources.