BALANÇO HÍDRICO PARA A CAATINGA NORDESTINA EM CENÁRIOS DE MUDANÇAS CLIMÁTICAS

Abstract

Climatological water balance is one of the most used methods for estimating deficit and water surplus, in addition to potential evapotranspiration. The biome under study was the Caatinga and in dry months, evaporation becomes high and causes water stress in the plant species. The objective of this study was to estimate the water balance (BH) for the Caatinga biome in optimistic and pessimistic scenarios of climatic changes, evaluating the variations of this balance, determining the potential evapotranspiration (ETP), water deficit (DEF) and water surplus (EXC ), comparing the spatial distribution between the climatological normal and the scenarios. Monthly data of mean temperature and precipitation of 42 localities were collected from January 1961 to December 2015. The scenarios used were based on the IPCC's fifth report, which defines the optimistic scenario RCP4.5 (increase in temperature of 1,4ºC and reduction of 15% in precipitation) and pessimistic scenario RCP8.5 (increase in temperature of 4,0ºC and reduction in precipitation of 20%). The value of 50 mm for the available water capacity in the soil was considered. After the BH calculation, the spatial distribution of the ETP, EXC and DEF values for the normal period and the optimistic and pessimistic scenarios were performed. After the BH calculation, the spatial distribution of the ETP, EXC and DEF values for the normal period and the optimistic and pessimistic scenarios were performed. The results showed that the evapotranspiration in the optimistic scenario increases without disparity in relation to the normal period. In the pessimistic scenario, the evapotranspiration increased a lot compared to the normal period. As for the water surplus in the optimistic scenario, the values decrease compared to the normal period. For the pessimistic scenario, the values come to reduce two, three or even four times the values found in the normal period. For the water deficit, the optimistic scenario significantly increased its values, while in the pessimistic scenario the values rose two to three times more, compared to the normal period. With this, the water balance for the Caatinga biome undergoes alterations both in the optimistic and pessimistic scenario considering a projection until the end of the 21st century.