Lake number as a predictor of turbulence generation on a slope

A crucial unanswered question in lake and reservoir management is whether the Lake number can be used to predict mixing in a lake. To address this question, three field campaigns with measurements of meteorological conditions, internal wave response by three thermistor chains, and dissipation of turbulent kinetic energy were conducted to study generation of turbulence on the sloping boundary of a small lake for Lake numbers between 0.1 and 1000. We measured the velocities in the bottom boundary layer with a high resolution acoustic current profiler and then computed the dissipation using the structure function method, which uses the spatial correlations of velocity along a beam to estimate the dissipation. During the low Lake number events, the dissipation of turbulent kinetic energy increased by up to four orders of magnitude above the specified background level of 10-10 m2s-3, except during the fall turnover when the wind energy was used in thermocline deepening. To evaluate the Lake number conditions under which turbulence will be generated at the slopes, a power law between the Lake number and turbulence intensity was derived, showing a near linear decrease of turbulence intensity with increasing Lake number.