The Study on Evaporation Losses from Medium and Small Reservoirs in Thailand

Abstract

Abstract

In the hydrological system, evaporation data plays a crucial role particularly for the water availability estimation of the reservoir system especially the medium and small size reservoirs which are located in the arid region and produce large volume of evaporation loss like Thailand. This paper aimed to present the pattern and tendency of evaporation data from medium and small reservoirs; Tubsalao, Pasakchonlasith, Nongplalai, Maekuang Udomthara, and Yangchum Reservoirs using the observed evaporation data together with applying 4 methods; water budget, empirical, mass transfer, and combination methods for estimation. The results showed high percentage in evaporation losses which ranged between 3.31%-21.01% of the active storage for all reservoirs. Moreover, the evaporation rate tended to be increased in the future mostly due to the high variation in meteorological data at the present time and the physical characteristics of the reservoirs. Additionally, using the empirical method for evaporation loss estimation also gave the lower percentage error than others.