Trends in climate extreme indices assessed in the Xingu river basin Brazilian Amazon

The Xingu River Basin (XRB), located in the Brazilian Amazon, is of great importance both in national and international contexts, especially regarding hydroelectric generation in the Belo Monte Hydroelectric Complex and forest conservation policies, given that the XRB is home to important conservation areas, such as the Xingu Indigenous Park. This paper analyzes climate extreme indices in the XRB, a region that lacks this sort of information. Trends in 22 climate extreme indices were evaluated, 11 of them for air temperature and 11 for rainfall, based on spatially gridded and high resolution daily data, for the period from 1980 to 2016. The temperature indices showed significant upward trends in daily temperatures (both maximum and minimum), an indication that, in recent decades, the days and nights have become warmer in the XRB. For rainfall, the indices indicated a downward trend in the central and southern regions of the XRB (Middle and Upper Xingu), and increasing rainfall in the northern region of the basin (Lower Xingu), however, with lower statistical significance when compared to air temperature indices. Commonly, the areas that presented statistically significant trends in the assessed climate extreme indices correspond to areas where there have been alterations in land cover due to increasing use in recent decades (areas of forest that were modified for pasture and agriculture) and in areas still preserved. This paper is an important tool to support decision making in management and strategic planning of water resources (for power generation and multiple uses) and for the elaboration of forest conservation policies (for combatting and controlling deforestation) in the XRB, in times when the region is under constant pressure from agribusiness for the expansion of agriculture and livestock.