The objective of this work was to characterize the hydrological behavior and the volume of water entering and leaving the Debossan river watershed, where an important water captation plant is situated, managed by the Nova Friburgo Water and Sewage Treatment Company LTDA (CAENF), within the 'Macaé de Cima' Ecological Reserve, Nova Friburgo-RJ. Data of daily flow and precipitation were collected from January/2002 to December/2004. Starting from these data, some hydrological parameters were calculated, such as specific flow and flow. The average rainfall for the period was 2,163.66 mm, being that the months december/2002 and january/2003 presented the greatest values. The annual average flow for the period was 0.86 m3/s, with December/2002 having the highest index and September/2004 the lowest. The average annual hydrological balance for the three years of measurements showed 1.923,04 mm of evapotranspiration, which was 88% of the conventional precipitation. This shows that the forest ecosystem works like a buffer effect on the amount of watershed water, keeping water in the months of higher rainfall and releasing it in the months of less rainfall. Analyzing the relation between the water entering in the watershed, the current use of the soil, and the amount of produced water, it was concluded that a well-preserved watershed is crucial to keep the flow constant during the year, besides the evident participation in the water quality.
Watershed; forest hydrology
