Long-term estimation of evapotranspiration from a tropical rain forest in Peninsular Malaysia

Field observations for estimating long-term evapotranspiration from a tropical rain forest were made in the Pasoh Forest Reserve, Peninsular Malaysia. The Penman-Monteith-Rutter model was applied to four-years of meteorological records to enable continuous estimation of evapotranspiration during dry and wet canopy conditions. The estimates show that the annual average total evapotranspiration, transpiration and interception loss for 1996-1999 were 1548 mm, 1218 mm and 331 mm, respectively, cf. annual rainfall of 1571 mm and net radiation of 1744 mm (water equivalent). Although a long dry period was included as a result of the strong El Ni (n) over tildeo in 1997 and 1998, evapotranspiration always accounted for a large portion of the net radiation.