The Study on Evaporation Losses from Large Reservoirs in Thailand

Abstract

Abstract

Hydrological data plays a crucial role for reservoir planning and management especially the reservoir evaporation loss which is regarded as the major data to reflect the amount of water supply of the reservoir system. This paper aimed to present the pattern and tendency of evaporation data from large reservoirs in Thailand; Ubolratana, Rajjaprabha, Srinagarind, and Sirikit Reservoirs using the observed evaporation data together with applying 4 methods; water budget, empirical, mass transfer, and combination methods for estimation. The results transparently showed the upward trend of evaporation rate at Ubolratana Reservoir due to the variation of meteorological data and physical characteristics of the reservoir. It was estimated that the evaporation loss at Ubolratana Reservoir was up to 19.68% of the active storage at the average water level. However, it showed the lower values of evaporation loss for Rajjaprabha, Srinagarind, and Sirikit Reservoirs which ranged between 3.92%-7.38%. In addition, it showed the downward trend of the evaporation rate for Rajjaprabha Reservoir and small upward trend for Srinagarind and Sirikit Reservoirs due to the climate variation in the area.