temperature dynamics in very shallow water bodies: the role of heat fluxes at the soil-water interface

Water Temperature represents one of the crucial factors driving the ecological processes in water bodies. Many contributions are available in the literature that describe temperature dynamics in deep basins as lakes or seas. Those basins are typically stratified which makes important to represent the vertical profile of the water temperature. Dealing with shallow water bodies, such as rivers, shallow lakes and lagoons, simplifies the problem because the water temperature can bu assumed uniform in the water column. Conversely, the heat exchange at the soil-water interface assumes an important role in the water temperature dynamics. Conversely, the heat exchange at the soil-water interface assumes an important role in the water temperature dynamics. Notwithstanding, very few studies and data about this process are available in the literature. In order to provide more insight on the soil contribution to water temperature dynamics, we performed ad hoc field measurements i the Venice lagoon. We selected a location on a tidal flat in the northern part of the lagoon, close to the Sant'Erasmo Island, where we measured the temperature within the first 1.5 m of the soil. We used the data to characterize the heat flux at the water-soil interface in different periods of the year and to develop a "point" model for describing the evolution of the temperature in the water column. The insight on the process provided by the data and by the point mode: i) enabled us to determine the soil thermal properties; ii) confirms the uniform profile of the water temperature in the water column; iii) demonstrates that the heat flux at the soil-water interface is comparable with other fluxes at the air-water interface and iv) highlights the important role exerted by advective water fluxes.