Evaporation from Lake Towada

Abstract

Merits and demerits of the direct measurements of evaporation from a lake by pan and of the indirect estimation by the turbulent transfer theory from measurements of wind, temperature and humidity profiles, were discussed based on some measurements. As a result, the practical estimation of evaporation from Lake Towada was carried out by means of the turbulent transfer theory based on observations of water temperature and of wind velocity, temperature and humidity at 3 m high above the lake surface, made at a represen-tative place on the lake. The amount of evaporation in a year was estimated to be 902 mm, and the annual variation of evaporation was found to be against our expectation ; evaporation was greater in cold season from September to March than in warm season from April to August.