Geographia Technica, Vol 12, Issue no. 1/2017, pp. 9-22


Quentin CHOFFEL, Laurent TOUCHART, Pascal BARTOUT, Mohammad AL DOMANY

DOI: 10.21163/GT_2017.121.02

ABSTRACT: Ponds are regarded as small waterbodies with a depth of less than 6m and an area of less than 100 ha. In the Limousine region (France), they usually bar small incised valleys, giving them a complex morphology. This morphology may separate the pond in several basins, as for the pond of La Ramade (45°47’04.3”N; 2°25’30.7’’E), theoretically suitable for a spatial variation of temperature. The pond has been implemented with 4 moorings chains composed of automatic thermistors, measuring the temperature every hour from the surface to the bottom. A meteorological station has been deployed close to the pond, in order to gather very precise meteorological information, in addition to the map of fetch and bathymetry. The working hypothesis is that even small waterbodies present a spatial heterogeneity of water temperature, so that the classic measurements only at one point give approximate values. The aim is to get a 3D overview of the thermal dynamic of a small waterbody for the purpose of a better understanding of its temperature dynamic, with heat content’s approach. In polymictic waterbody, the temporal but as well spatial variations of the heat content are together numerous and varied. The first results bring us the autonomous function of the bays and sheltering places, while the open water has a predictable function. Some parameters such as the fetch, the sheltering by vegetation or the bathymetry plays a more or less important role in the particularity of each basin. The heat content’s methodology shall be improved by consideration of the spatial variation of the pond’s temperature.

Keywords: Heat content, Water temperature, Pond, Spatial variation, Water Framework Directive.

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