Laboratory study on periodic heat exchanges between water and sediment in extremely shallow flows

Extremely shallow lakes are found in the Altiplano, or high plain, of South America, in which large diurnal temperature variation occurs. In these shallow systems, the water temperature is control by head exchanges with the atmosphere and with the bottom sediments. As a consequence, the amplitude of the daily fluctuations in water temperature is reduced by heat exchanges with the bottom sediments. This paper describes a study of the thermal amplitudes in the water column as a function of of two dimensionless numbers, named Π1 and Π2. These dimensionless numbers include the thermal properties of water and sediments, besides the properties of the atmospheric source. Two experimental setups were constructed and used in order to obtain the water temperature times series, and the thickness of the diffusive sublayer.