Hydrothermal Analysis of Lakes and Reservoirs

The impact of Hunter Rouse on the application of fluid mechanics to hydraulic engineering practice in the United States is reviewed. The development of physical and mathematical techniques for predicting the hydrothermal structure of lakes and reservoirs during the past fifteen years is discussed. Laboratory models have played a key role in the development and testing of early mathematical models based on the vertical diffusion concept. The sensitivity of these models to variations in turbulent diffusivity, internal heat absorption and vertical advection due to inflows and outflows is demonstrated. A wind-mixing model is proposed as an alternative to specifying temporal and spatial variations in the vertical diffusivity. The wind-mixing algorithm converts turbulent kinetic energy input by wind shear to potential energy through entrainment of hypolimnetic water across the thermocline. An iterative technique is used to achieve a heat balance based on meteorological inputs averaged over hourly or daily time steps. The temperature predictions of the numrical model are compared with field data for a number of lakes and reservoirs.