Simulation of Green and Blue Water Impacts Caused by Climate Changes in the Apucaraninha River Watershed, Southern Brazil (Simulação dos Impactos da Água Verde e Azul Causados pelas Mudanças Climáticas na Bacia Hidrográfica do Rio Apucaraninha...)

Abstract

Climate changes may generate significant impacts in the hydrological cycle. It is important to recognize modifications in green water (water stored in soil followed by the consumption of the vegetation) and blue water (water that flows into rivers, lakes, wetlands and shallow aquifers) availability in consequence of climate change modifications. The mathematical modelling is used to simulate the effect of climate change scenarios in hydrological processes in watersheds. This study aimed to evaluate the impacts of climate change in blue and green water in Apucaraninha River Watershed, Southern Brazil, considering the climate scenarios A2 and B2, pessimistic and optimistic, respectively, about greenhouse gases emissions developed by IPCC. SWAT was calibrated and validated using daily streamflow from 1987 to 2012. Climate scenarios A2 and B2 were used to simulate the hydrological conditions for the period 2071-2100. The model presented satisfactory fit compared to the observed data allowing the simulation of the current hydrological conditions, therefore permitting the simulation of future climate change impacts on green and blue water. We found that despite the increase in potential evapotranspiration of 19% and 12% for A2 and B2 scenario respectively, caused by the increase in temperature, the reduction in rainfall amount induced to a reduction in actual evapotranspiration, which correspond to green water, and a reduction of 1% for A2 scenario and 14% for B2 scenario in blue water availability.