Summary
The present work is based on Meteorological data for the period 1965-1973 collected at Ducke Forest Reserve of the Instituto Nacional de Pesquisas da Amazônia (INPA) located at Km 26 of the Torquato Tapajós Highway. Potential Evapotranspiration was estimated by Thornthwaite's and Penman's methods and the Water Balance was measured by Thornthwaite's and Mather's methods.