Potenciais efeitos da mudança do clima sobre a hidrologia do Pantanal.

O Pantanal compreende uma área de aproximadamente 150.000 km2 na Bacia do Alto Paraguai (BAP), cujo relevo varia entre 80 e 200 m. A rede de planícies inundáveis do Pantanal está conectada com as planícies do Chaco paraguaio ao sul. Os rios de leitos rochosos nas adjacências de planalto tornam-se rios aluviais ao adentrar a planície pantaneira, a qual tem sido progressivamente preenchida por sedimentos carreados por este sistema de rios. As falhas são evidentes na morfologia da bacia, condicionada pela ocorrência de terrenos précambrianos na borda ocidental da bacia e a drenagem aluvial moderna dentro da bacia. A sedimentação ocorre em um extenso trato aluvial deposicional formado pela planície do Rio Paraguai e por vários leques fluviais.bitstream/item/151519/1/ADM161.pd

Avulsions Drive Ecosystem Services and Economic Changes in the Brazilian Pantanal Wetlands

The Pantanal wetland is a mosaic of landscapes that brings together rich biodiversity with the valuable activities of fishing, tourism and ranching. Human occupation and land use in the headwaters have intensified the rate of channel avulsions in the lower reaches of the largest megafan on the Taquari River. This study evaluates the long-term changes of landscapes in the active depositional lobe of the Taquari megafan from the perspective of local communities of pantaneiros. Maps derived from multiple decades of multispectral Landsat data have proven useful for studying land cover changes through the relationship between dry (terrestrial vegetation and soil/dry pastures) and humid landscapes (open waters, aquatic macrophytes and wet soils), as well as through Sankey diagrams and spatiotemporal mapping with Boolean operations according to the rate of dryland recovery. We found that dryland recovery associated with an older and smaller avulsion (known as Zé da Costa) is analogous to that of a most recent and much larger avulsion (known as Caronal), which is still ongoing and has greater importance due to the scale of the impacts. Land value and fish capture depreciate as the partial Caronal avulsion still evolves, increasing the likelihood of environmental conflicts. While pantaneiros no longer profit from ecosystem services of provision (e.g., livestock or fishing), dryland recovery may deliver quantifiable ecosystem services of regulation. The strengthening of partnerships among stakeholders and the implementation of environmental compensation mechanisms are central for the best management of the Pantanal\u27s megafans that ensure quality of life for all pantaneiros

Diagnóstico e prognóstico de serviços ambientais de reconstrução de canais de rios na avulsão do Rio Taquari na região do Caronal.

Arrombados e avulsões são fenômenos inerentes a sistemas de rios distributários em lobos ativos de megaleques. No Pantanal, esses fenômenos já aconteceram no passado e o mais recente e de grandes proporções ocorreu na região do Caronal, no Rio Taquari. Este estudo traz novas análises quali-quantitativas da dinâmica espaço-temporal de arrombados no Caronal e da deposição de sedimentos (splay) na avulsão que se estabeleceu na região do Paiaguás. As análises permitiram mapear no tempo as mudanças de surgimento e desaparecimento das arrombados, bem como criar um modelo scale-invariant de previsão indicando que em 2050 o tamanho e o comprimento máximo da área de deposição de sedimentos na avulsão deverão ser respectivamente de 1.258 km2 e 100 km. Portanto, no longo prazo, a canalização do rio Taquari no Paiaguás deverá ser estabelecida caso sejam mantidas as condições ecohidrológicas e dos serviços ambientais presentes

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

Papel das macrófitas aquáticas na sucessão ecológica em sistemas fluvio-lacustres do Pantanal: Lago Uberaba.

As macrófitas aquáticas são importantes componentes do ecossistema úmido que podem promover mudanças e a evolução de paisagens naturais. Os sistemas de informação geográficas ou SIGs auxiliam na identificação de áreas com mudança na cobertura vegetal em planícies inundáveis do Pantanal. O foco deste estudo foi determinar o papel das macrófitas aquáticas flutuantes nas margens do Lago Uberaba situado em um sistema fluvial. O mapeamento temático em imagens georreferenciadas do satélite Landsat no período seco revelou um decréscimo de 21,4% da área de água aberta do lago ao longo de 30 anos (-4,7 km2 /ano). Entretanto, pouca correlação foi encontrada entre a área de água aberta do lago e a cota do rio Paraguai nesse período. A taxa de crescimento da cobertura de macrófitas no lago foi de 1,4 km2 /ano. Os dados sugerem que o crescimento das macrófitas independe da quantidade de chuva e da vazão de água na região. As áreas classificadas como terrestres também tiveram aumento. Para explicar as observações satelitárias históricas, buscou-se inserir nesse contexto o processo de sucessão ecológica vegetal. Nesse processo, plantas r-estrategistas (predomínio aquático) dão lugar a plantas k-estrategistas (predomínio terrestre) em direção ao clímax. Estudos adicionais no Lago Uberaba e outros análogos serão necessários para melhor avaliar essa hipótese formulada para descrever a evolução de processos geomorfológicos dinâmicos na planície de inundação do Pantanal

River avulsions on the Taquari megafan, Pantanal wetland, Brazil

The Pantanal wetland is located in a tectonically active interior sedimentary basin in west-central Brazil. The south-flowing Paraguay River is the trunk-river of an alluvial constructional landform comprising several large alluvial fans, the largest one of which is the Taquari megafan. The Taquari River flows in two distinct geomorphologic zones within the megafan. Entrenched on sediments of Pleistocene fan lobes, the Taquari River flows in a 3 to 5 km wide meander belt in the upper fan, where avulsion is hindered by entrenchment. Downstream of the intersection point, stream discharge progressively decreases and the Taquari River becomes narrow and shallow toward the Paraguay River plain. Within the distributary fan lobe, the channel-levee sandy complex is topographically higher than the adjacent floodplains and avulsion is a natural consequence of crevasses in the natural levees. Many channel avulsions have occurred during the last decades and documented cases show that significant channel changes may take place in a few years. Beginning with crevassing in 1988 and ending with the abandonment of the former channel in 1998, the river completely changed course in the lower fan. Presently, a major avulsion is occurring in the upper portion of the growing fan lobe, where many crevasses have appeared in the natural levees with associated splays onto the floodbasin. New anastomosed channels have formed north of the Taquari River, but downstream of them the flow is unconfined and the water spreads into natural floodbasins. This avulsion is still in process and allows observation of channel evolution, the geomorphic features produced, the sedimentary processes involved, and resulting effects. If the new channels do not rejoin the main channel, the river mouth may abandon its present master channel and shift to a position a hundred kilometers north from its present position. A large volume of sediment has been transferred to the floodbasin, with progradation of crevasse splay deposits over fine overbank sediments. Many geomorphic features, recognizable in satellite and radar images, clearly show that avulsion has occurred many limes before in the Taquari River. Avulsion belt deposits and former diverted channels testify to ancient avulsion events within the fan lobe and show that progradation of splays onto the floodbasin is the most important infilling process within the Taquari distributary fan lobe. The avulsion process in the lower Taquari River has accelerated in the last 30 years, along with the magnitude of flooding. Pasture and intensive agriculture in the catchment area has increased the sediment supply to the wetland, but larger floods are also a consequence of higher rainfall since 1973. Avulsion and floods have been a cause of great concern among the local population and landowners. Before human intervention in attempting to control floods, however, a better understanding of the avulsive river system is needed, especially because a major navigation project including the channelization of the Paraguay River was recently proposed. (c) 2005 Elsevier B.V. All rights reserved