Priority setting for restoration in surrounding savannic areas of the Brazilian Pantanal based on soil loss risk and agrarian structure.

Soil health is at the core of the sustainability agenda. As in many agroecosystems in the tropics, soil erosion is a major issue in poorly managed pasturelands. A noteworthy case is located in the Upper Taquari River Basin (UTRB), as part of the Upper Paraguay Basin on the plateau with drainage waters for the Taquari megafan in the Brazilian Pantanal. Here we combine slope (S-factor), erodibility (E-factor), rainfall-rainy day ratio (R-factor), and vegetation and soil indices (C-factor) to locate erosion risk and prioritize eco-engineering interventions via palisades and small dams in UTRB. The method consisted of assessing distinct weights between Universal Soil Loss Equation (USLE) factors in a GIS platform, providing 35 combinations of classes as low, moderate, high, and very high erosive risk. The validation of the method was based on the ravine and plain ground truths obtained from high-resolution raster data. The best weight of USLE factors aids to locate critical erosive sites and vegetation patterns. Then, erosion risk and interventions were analyzed according to land use and rural property sizes in the government's Rural Environmental Registry (CAR) database. Overall, the natural factors of slope and erodibility in a proportion of 25% and 75% in GIS algebra provided the best mapping accuracy result. About 65% of the UTRB has high or very high erosion risks, and 70% of the available area can be acknowledged as degraded pasturelands. A total of 4744 erosion interventions were recorded, with an accuracy of 65.28% and 61.15% for check dams and palisades interventions, respectively. The number of necessary interventions in areas of native vegetation was almost 50% higher than in pasturelands. Even though micro landowners occupy most of the watershed, large properties have about ten times as many areas at high risk of erosion. The mutual cooperation between properties, independently of size, is supported by governmental public policies like incentives for ecosystem services restoration of critical gullies, with CAR compliance and fiscalization.

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.