In Brazil, the number of commercial plantations of forest species has increased considerably in recent decades. However, the potential impacts of this increase on water resources are still unknown. The objective of the present study was to model the water balance in a watershed, home to a commercial plantation of the Eucalyptus grandis x urophylla hybrid in eastern Minas Gerais, Brazil. This study was conducted in an experimental watershed with total area of 40 ha during the hydrological year extending from october 2009 to september 2010. The main source of water entering the system, via rainfall, was monitored as part of meteorological data by an automatic station installed within the study area. The main water outlets were estimated by the modified Penman-Monteith equation and by measuring the runoff generated at the basin output. Of the total precipitation (1123 mm) during the year, 9% (106 mm) was lost via interception, 66% (740 mm) via crop transpiration and 11% (119 mm) by soil evaporation, which together correspond to approximately 86 % of water entering the watershed. Of the total outflow generated (~ 147 mm), only 4.29 mm (0.4%) were converted into surface runoff. It can be concluded that during the hydrological year analyzed, the balance between the main water inputs and outputs in the watershed was equalized, without jeopardizing the availability of water in the natural waterway.
Forest hydrology; Rutter model; Transpiration
