Abstract
Dense haze caused by the forest fire and the slash-and-burn method of agriculture covered a wide area of Southeast Asia in summer and autumn, 1997. The dense haze impacted on not only human health and social activities but also the ecosystem there. Ground water level in a peat swamp forest and solar radiation in open areas were Ineasured in Central Kalimantan from September 1993 to December 1997. The ground water level dropped remarkably to 98 cm below the ground surface because of small rainfall from July to September in 1997. Solar radiation also decreased to about 40 % of normal condition in September. Daily evapotranspiration from the peat swamp forest was estimated from the hourly data of ground water level in the forest. The evapotranspiration showed a linear regression with daily total solar radiation. From this regression, evapotranspiration in September 1997 was estimated to be around 50 % of that in normal condition of 3-4 mm/day. Using this relationship between evapotranspiration and daily change of ground water level, it was estimeted that the dense haze depressed the evapotranspiration of the forest to around 50 % of normal year at the end of September, 1997.
