Abstract
In this paper the writer studied the annual temperature change of impounded water at the Miura reservoir, Nagano prefecture, for purpose of power generation.
Though the change of impounded water in a natural lake had been precisely studied by late Dr. S. Yoshimura, the change ofimpounded water at an artificial reservoir has not been clear. So, he first intended to study a correspondence about an annual temperature change of water between a natural lake and an artificial reservoir.
The limnological appreciation is thought to be as follows. Al though a reservoir gives rise to a larger fluctuation of a water surface, its annual change of impounded water shows a considerable correspondence with that of a natural lake. That is to say, in summer the temperature gradient toward the bottom becomes a direct stratification and in winter it turns to a inverse stratification.
The obvious difference in comparison with a case of a natural lake is found out by a thin or lacking of a epilimnion, whai chscuorvofeafrc se water and shows a higher temperature, and temperature of deep part of reservoir is always higher than 40C in summer. The another difference is the fact in winter that cold water showing about 1.2deg;C goes down to a deep part.
