Landscape changes in avulsive river systems: Case study of Taquari River on Brazilian Pantanal wetlands.

The Pantanal is an important active sedimentary basin in central South America where highly diverse flora and fauna are sustained by seasonal floods. Intense land use in the catchment areas enhanced sediment load and destabilized avulsive river systems in the plains. A well-known avulsion in the Taquari River during the 1980-90s, called "Zé da Costa", has shifted the river mouth and drastically changed the nearby landscapes, making them difficult to map because of the hard access and the large variations in spectral and spatial attributes of raster data like Landsat images. Therefore, we developed a useful method to map and explore landscape changes in "Zé da Costa" avulsion that combines geotagged field pictures, randomly selected high-resolution orbital truths, normalized difference vegetation index, digital elevation models, linear spectral mixture models and Landsat historical imagery in pixel-based and object-oriented supervised classifications. We found that bands in green, red, and near-infrared spectra provide better mapping results with object-oriented algorithms for deriving and studying temporal dry/wet ratio dynamics. The temporal analyses of the dry/wet ratio showed that avulsions in the Taquari River have the potential to change permanently the "Zé da Costa" area into a dry landscape, making it susceptible for land use (deforestation and fire), except areas seasonally inundated by the floods of the Paraguay River. Overall, our method might be also useful for long-term studies of land use and climate change in avulsive rivers in wetlands around the world.

Amazon rainforest modulation of water security in the Pantanal wetland.

The Pantanal is a large wetland mainly located in Brazil, whose natural resources are important for local, regional and global economies. Many human activities in the region rely on Pantanal's ecosystem services including cattle breeding for beef production, professional and touristic fishing, and contemplative tourism. The conservation of natural resources and ecosystems services provided by the Pantanal wetland must consider strategies for water security. We explored precipitation data from 1926 to 2016 provided by a regional network of rain gauge stations managed by the Brazilian Government. A timeseries obtained by dividing the monthly accumulated-rainfall by the number of rainy days indicated a positive trend of the mean rate of rainy days (mm/day) for the studied period in all seasons. We assessed the linkage of Pantanal's rainfall patterns with large-scale climate data in South America provided by NOAA/ESRL from 1949 to 2016. Analysis of spatiotemporal correlation maps indicated that, in agreement with previous studies, the Amazon biome plays a significant role in controlling summer rainfall in the Pantanal. Based on these spatiotemporal maps, a multi-linear regression model was built to predict the mean rate of summer rainy days in Pantanal by 2100, relative to the 1961-1990 mean reference. We found that the deforestation of the Amazon rainforest has profound implications for water security and the conservation of Pantanal's ecosystem services.

The 2009 earthquake, magnitude mb 4.8, in the Pantanal Wetlands, west-central Brazil.

The main goal of this paper is to characterize the Coxim earthquake occurred in June 15th, 2009 in the Pantanal Basin and to discuss the relationship between its faulting mechanism with the Transbrasiliano Lineament. The earthquake had maximum intensity MM V causing damage in farm houses and was felt in several cities located around, including Campo Grande and Goiânia. The event had an mb 4.8 magnitude and depth was 6 km, i.e., it occurred in the upper crust, within the basement and 5 km below the Cenozoic sedimentary cover. The mechanism, a thrust fault mechanism with lateral motion, was obtained by P-wave first-motion polarities and confirmed by regional waveform modelling. The two nodal planes have orientations (strike/dip) of 300°/55° and 180°/55° and the orientation of the P-axis is approximately NE-SW. The results are similar to the Pantanal earthquake of 1964 with mb 5.4 and NE-SW compressional axis. Both events show that Pantanal Basin is a seismically active area, under compressional stress. The focal mechanism of the 1964 and 2009 events have no nodal plane that could be directly associated with the main SW-NE trending Transbrasiliano system indicating that a direct link of the Transbrasiliano with the seismicity in the Pantanal Basin is improbable.