The Tocantins–Araguaia Basin covers an extensive area of Brazilian territory and has a water reservoir system installed in a cascade that is very important for water storage and hydropower production. There is concern about the use of this resource because of the current tendency of surface water reduction in the reservoir systems. Sustainable management can help to guarantee the water supply and the hydropower supply. However, accurate data on the monitoring parameters are required. This study aims to analyze which factors most influence the changes in the areas of water reservoirs and, subsequently, the changes in the water availability. Trends, correlations, and principal component analyses (PCAs) were used to assess the association between the areas of water reservoirs and the liquid evaporation, discharge, precipitation, and land use and land cover (LULC) in the basin. We observed that the precipitation did not decrease significantly. On the other hand, changes in the LULC and the areas of reservoirs were highly correlated with each other. The PCA also showed a strong association between meteorological factors and the areas of reservoirs. In conclusion, this study showed that reductions in the areas of water reservoirs are mostly related to deforestation and reduced reservoir discharge rather than climate change. This paper provides a straightforward approach to monitoring reservoir changes based on the tendencies of some parameters that are strongly correlated with reservoir changes.

In the western Andes, climate changes have led to drastic ecological changes during the Pleistocene and Holocene. Given the debate surrounding precipitation pattern changes and the lack of research on lakes in the Chilean Altiplano, this study aims to assess recent climate changes. The paper presents an innovative methodology based on Google Earth Engine (GEE), utilizing fluctuations in water levels in endorheic lakes as natural precipitation indicators. Three lakes (Chungará, Miscanti, and Miniques) in isolated drainage systems were studied, where changes in water levels directly reflect rainfall variations. Data from Landsat-OLI 8, Landsat-ETM+, Landsat-TM 5, and MODIS spanning 31 years were processed using the Google Earth Engine platform. The shapes of the water bodies were extracted using hue saturation value (HSV) composites. The surface areas of the lakes were compared with precipitation data from national meteorological stations and the Tropical Rainfall Measuring Mission (TRMM) using linear regression analyses. Both lake area and rainfall volume showed a decrease over time, with varying trends depending on environmental conditions. However, the analysis consistently indicates a reduction in the area and volume of Chilean lakes corresponding to observed rainfall patterns over the past three decades.

Due to the COVID-19 pandemic, reductions of nitrogen dioxide (NO2) concentrations in the atmosphere were observed in several countries, since the gas is related to the burning of fossil fuels from means of transport. This study aims to identify the changes in the NO2 emission pattern associated with measures to restrict circulation with confinement during the COVID-19 pandemic, in the urban areas of Brasília (DF), Anápolis and Goiânia (GO). Tropospheric NO2 data were collected through the TROPOMI sensor, from the Sentinel-5P satellite, and precipitation data by satellite monitoring from the Global Precipitation Measurement (GPM) network. The average values ​​of NO2 and precipitation (mm/h) were calculated for each of the images between the years 2019 and 2021, as well as the weekly moving averages for each urban area. Thus, six two-month periods were defined, and the ratio of the moving average between the years 2020/2019 and 2021/2019 was calculated. In the aforementioned period, a decrease in the density of the NO2 column was observed in 2020, with a later increase, in 2021, in the same period and in the three regions. In Brasília the drop was more expressive, being, on average, -9.35%, followed by Goiânia with -2.61% and Anápolis with -1.34%. The biggest increase was observed in Goiânia, with +30.3%, followed by Anápolis, +19.30%, and +16.08% in Brasília. Despite the drop in emissions in 2020, in the following year there was an increase on the NO2 emission levels.