Estimating evapotranspiration and understanding its variations in a seasonal dry dipterocarp forest, western Thailand

Abstract

We analyzed 3-year eddy-covariance data (2009-2011) to investigate the evapotranspiration (ET) in a dry dipterocarp forest in western Thailand. The objectives of our study were: (1) to quantify ET in this seasonal forest and 2) to understand the diurnal and seasonally patterns of ET and its drivers. The diurnal patterns of ET was characterized by a rapid increase during early morning, reached the highest at noon and decreased until sunset. Variations during the night time were small. On the seasonal scale, ET was positively correlated with seasonal rainfall and soil water content and negatively correlated with vapor pressure deficit. The annual average of ET was 2.55±1.20 mm day-1. The average ET in wet season (3.61 ±0.39 mm day-1) was higher than during the dry season (1.15±1.17 mm day-1). The annual, wet and dry season totals of ET averaged during these three years were 935±117, 222±87 and 628±34 mm respectively. The annual ET accounted for about 95% of total annual rainfall.