Chikita, K.A.; Oyagi, H.; Amita, K. A Thermal Regime and a Water Circulation in a Very Deep Lake: Lake Tazawa, Japan. Hydrology2024, 11, 40.
Chikita, K.A.; Oyagi, H.; Amita, K. A Thermal Regime and a Water Circulation in a Very Deep Lake: Lake Tazawa, Japan. Hydrology 2024, 11, 40.
Chikita, K.A.; Oyagi, H.; Amita, K. A Thermal Regime and a Water Circulation in a Very Deep Lake: Lake Tazawa, Japan. Hydrology2024, 11, 40.
Chikita, K.A.; Oyagi, H.; Amita, K. A Thermal Regime and a Water Circulation in a Very Deep Lake: Lake Tazawa, Japan. Hydrology 2024, 11, 40.
Abstract
A thermal system in very deep Lake Tazawa (maximum depth, 423 m) was investigated by estimating the heat budget. In the heat budget estimate, the net heat input at lake surface and the heat input by river inflow and groundwater inflow were considered. Then, the heat loss by snowfall onto lake surface was taken into account. Meanwhile, lake water temperature was monitored at 0.2 m to the bottom by mooring temperature loggers for more than two years. The heat storage change of the lake from the loggers was calibrated by frequent vertical measurements of water temperature at every 0.1 m pitch by a profiler with high accuracy (± 0.01 °C). The heat storage change (W/m2) obtained by the temperature loggers reasonably accords to that from the heat budget estimate. In the heat budget, the net heat input at lake surface dominates the heat storage change, but the significant heat loss by river inflow sporadically occurred, which is caused by the relatively large discharge from a reservoir in the upper region. How deep the vertical water circulation in the lake occurs in winter was judged by the differences between water temperatures at 0.2 m depth and bottom and between vertical profiles of dissolved oxygen over winter. It is strongly suggested that the whole water circulation does not occur every winter, if any, very weak.
Keywords
heat budget; deep lake; groundwater inflow; snowfall effect; water circulation
Subject
Environmental and Earth Sciences, Environmental Science
Copyright:
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