Impactos das mudanças climáticas e do uso da terra na produção hidrelétrica na Amazônia Oriental.

Abstract

In today's anthropogenic world, nature is increasingly seen as a resource, water and soil are heavily used, shaped, and rearranged for the benefit of global socioeconomic development. However, the impacts of these unbridled changes on the environment may contradict their benefit. In this study our objective was to quantify the impacts of land use and land cover change (LULCC) and Climate Change (CC) on some hydrological processes: streamflow, runoff and evapotranspiration in the Tocantins-Araguaia Watershed (TAW). And further, to investigate these impacts on the production of hydropower from the Tucuruí Hydropower Plant (THP) in the TAW. Finally, to identify whether there will be implications of these changes on hydropower revenues. To this end, the Soil and Water Assessment Tool (SWAT) hydrological model was used, from the model calibrated and validated for the TAW, four isolated LULCC and four climate change scenarios plus a coupled LULCC and CC scenario were constructed to assess the impacts of these anthropic activities on hydrology, power generation and monetary revenues. For this purpose, we used two General Circulation Models (GCM), HadGEM2-ES and MIROC5 with moderate (+4.5 W/m2) and severe (+8.5 W/m2) radiative forcing from carbon dioxide emissions in the atmosphere (Representative Concentration Pathways). For LULCC scenarios we replaced forest areas with grassland, then agriculture, then reforestation vegetation, and finally returns to forest. The results indicated that there will be a 36% increase in the flow of the TAW by mid-century, due to a 15% increase in runoff and a 3.5% reduction in evapotranspiration, according to the isolated LULCC scenarios. However, the surplus water cannot be converted into energy by the THP and there will be a reduction of up to 65% in annual energy production. For the CC and CC+LUCC scenarios, a 74% annual decrease in flow is expected and a 98% seasonal decrease during winter compared to baseline in the most pessimistic scenario, causing a 135% annual deficit in revenue for the THP for this scenario. The scenario with the smallest impact on monetary revenue would raise $8.4 million, while current THP revenue is estimated at $3.1 billion. Finally, we conclude that in the long-term CC can have a greater impact than regional LULCC, on hydrology and energy production in the TAW, because of the reduction in water input to the system, i.e., rainfall.