A study on the thermal convection using a thermotracer at Kagami dam lake [Kochi, Japan]

• Published in: Research Reports of Kochi University. Natural Science and Agriculture (Japan) Vol. 57
• Main Authors: Niwa, Y, Kamii, Y, Kimura, H, Chikamori, K
• Format: Journal Article
• Language: Japanese
• Published: 01.12.2008
• Subjects: BARRAGE; CONVECCION; CONVECTION; DAMS; ECHANGE THERMIQUE; HEAT TRANSFER; LAC; LAGOS; LAKES; REPRESAS; TECHNIQUE DES TRACEURS; TECNICAS DE TRAZADORES; TRACER TECHNIQUES; TRANSFERENCIA TERMICA
• ISSN: 0389-0244

Thermal convection at Kagami Dam Lake in Kochi Prefecture, was investigated using a thermography whose brand name was thermotracer manufactured by NEC-Sanei Inc. from October 29 to December 24, 1999. From the investigation, the following facts have been concluded. 1. The convection cells are classified into two types; the smaller one whose diameter is 20-30cm lasts one minute or so, the larger one with more than 1 m of diameter lasts at least 20 minutes. The smaller cells had often been observed during November. On the other hand, the larger ones were observed in December. On December, 24, 1999, some smaller cells, every now and then, were seen around the larger cells. Judging from the observations, cells were getting larger as colder season came nearer. The size was thought to be affected by the convection scale (depth). 2. Applying Kimura's Vertical One-dimensional Convection Model, the settling down velocities and discharges were calculated. According to them, they are not uniform but some acceleration phenomena have been observed. 3. Applying the above-mentioned model to December 24th data, calculation was failed because higher water temperature had been observed at the bottom.