Abstract
Kitagata lake which loctes Awara City 25 km north of Fukui City, Japan is a typical brackish lake. The water quality of Kitagta Lake has been chronically eutrophic. Io order to improvement the water quality, it is necessary to clarify the processes of water and pollutant cycle in the lake basin. Two method of evaporation measurement has been carried out to make the water balance clear. One is direct measurement by using double columns simple lysimeters and other is estimated based on the Bowen ratio method. The estimated values well simulated the trend of diurnal variation of evaporation. The mean error between estimated and observed values, however, was as large as about 26%. The error of cumulative evaporation during day time was 14% less than former one.
