Impacto de cenários de mudanças climáticas no balanço hídrico da Amazônia Ocidental.

Abstract

The main objective of this study was investigate possible alterations in the climatic water budget components associated with different scenarios (A2 and B2) of the IPCC to Amazonian Western (Acre, Amazonas, Rondônia and Roraima). It was used as reference the current conditions and the climatic interannual variability during an episode of La Niña 1988/89 and another of El Niño 1997/98. The climatological data of air temperature and precipitation from the INMET (1961-2005), CEPLAC (1983-1999) and NCEP/NCAR reanalysis (1983-1995) were used in the present study. The Thornthwaite and Mather (1955) method was used in the elaboration of the climatic water budget. The results of the projections show drier climate trends and decrease of the soil moisture, reduction in the rivers discharge, increase in the fire risk, showing that the potential evapotranspiration presents higher value than actual evapotranspiration, producing an increase of the atmospheric relative humidity, decrease in the runoff for the Amazonian Western up to 2100. The projections indicate that the climate becomes sub-humid or sub-humid dry, due to the increase of the aridity degree in the east of the Amazonian Western and in the Rondônia and Acre states. Also, has been verified interannual variability of the water budget components through of the analysis of them in a episode of La Niña and another in El Niño. In El Niño episode the atmospheric conditions over the Amazonian Western present dryer than the climatic average, however, in the La Niña the results were inferior than the obtained to A2 scenario showing increase and decrease of the precipitation and B2 presenting decrease.