Assessment of wash load transport in the Araguaia River (Aruanã Gauge Station), central Brazil

With an area close to 377,000 km2 and a mean annual discharge of ~ 6,420 m3 s-1 the Araguaia River is the main river draining the central highlands of Brazil. The Araguaia Rivers is a particularly sandy anabranching system that has been suffering geomorphologic and sedimentary changes because of the effect of high rates of deforestation during the last decades. Little is known, however, on the amount of wash load transport. We will present the first relatively systematic results on wash load transport for the Araguaia River at the Aruanã gauge station. The drainage area at Aruanã is 77,000 km2 and the mean annual discharge is ~1,200 m3 s-1. A total of 140 samples from 20 field surveys were analyzed and the wash load transport was estimated. We calculated that from 2001-2007 the average annual transport oscillated between 8 Mt yr-1 and 6 Mt yr-1. An interesting aspect that makes the Araguaia unique when compared to other large alluvial rivers of Brazil is the relation between sandy load and wash load. The Araguaia at Aruanã carries up to ~57% of the total sediment load as sandy load. We can now conclude that wash load just represents near 43 to 49% of the total sediment load in this system. Our results demonstrate that previous works overestimated the total wash load transported by the Araguaia. Taking into account that these are the first systematic results on wash load transport in the Araguaia, proposed human interventions in this system affecting sediment flows such as dams can be extremely harmful for the fluvial system. A more systematic analysis of sediment transport and an integrated and multidisciplinary plan of basin management must be done so that the detrimental effects of these human interventions will be understood

Hydro-geomorphologic controls in the vegetation of the Araguaia river floodplain, Brazil

A existência de diferentes tipologias vegetais na planície aluvial do médio Araguaia apresenta um padrão de distribuição determinado pela dinâmica fluvial do canal e pelas características morfossedimentares das unidades que formam a planície aluvial. O objetivo deste trabalho foi discutir como a dinâmica fluvial atua nos processos de sucessão vegetacional, considerando os processos de erosão e deposição, dentro de um curto intervalo temporal, e a dinâmica de cheias. O processamento de informações dos mapas das unidades morfossedimentares da planície e das unidades vegetacionais resultou no mapa de unidades morfovegetacionais. Verificou-se que as unidades vegetacionais se distribuem e compõem, de modo diversificado, um mosaico vegetacional pela planície. Entre 1965 e 1997, a ação dos processos erosivos, nas margens do canal que consomem a planície aluvial, tem removido principalmente vegetações arbóreas de grande porte, e as altas taxas de sedimentação contribuem para a formação da unidade geomorfológica mais jovem da planície, que é colonizada, sobretudo, por espécies herbáceas.The existence of different vegetable typologies in the alluvial plains of the middle Araguaia presents a pattern of distribution determined by the fluvial dynamic of the channel and the type of sediments that form different units of the alluvial plain. The purpose of this study was to discuss how the fluvial processes acts in vegetation succession, considering the erosive and sedimentary activities within a short period of time, as well as the flood dynamic. The combined information from morphosedimentary unit maps of the alluvial plain and the vegetation units allows the elaboration of the map of morphosedimentary units. It was possible to verify that the vegetation units were distributed in a diversified way along the alluvial plain, composing a vegetation mosaic. Between 1965 and 1997, the action of the erosive processes in the banks of the channel that consume the alluvial plain removed in particular large arboreal vegetation types, and the high rates of sedimentation contribute to the formation of the most recent geomorphologic unit of the plain, which is being colonized especially by herbaceous species.Facultad de Ciencias Naturales y Muse

Relationship between hydrology and aquatic ecosystems in the Araguaia river floodplain

O rio Araguaia se constitui no principal sistema fluvial que percorre o Brasil central. Neste artigo, são apresentadas algumas observações sobre o seu comportamento hidrogeomorfológico e suas aplicações no estudo de ecossistemas aquáticos. Os resultados foram gerados pelo processamento de dados de vazão de uma série histórica de 35 anos de registro (1970 a 2004), em nove estações hidrológicas, envolvendo o alto, médio e baixo curso. A distribuição de vazões no curso médio resulta atípica nas cheias extremas, pois o rio perde até 30% de sua vazão. No total, foram definidos três tipos de enchentes e dois mecanismos particulares de armazenamento e transferência de fluxos, que explicam as perdas de fluxos no médio curso. Três são os principais fatores condicionantes da perda de vazão: a) a existência de uma planície aluvial bem desenvolvida, b) a existência de um complexo de sistema de lagos na planície aluvial, c) a vegetação dominantemente arbórea, que freia a onda de cheia e contribui para o armazenamento de água na planície aluvial.The Araguaia river is the most important fluvial system draining the Cerrado biome of Brazil. Results are presented here on the hydrogeomorphologic behavior of this fluvial system and its effect on the floodplain ecosystems. Discharge from nine gauge stations in the upper, middle and lower course of the Araguaia River, from 1970 to 2004, were analyzed. The hydrological regime depends strongly on the tropical wet-dry climate, with floods from January to May and low water between June and September. In the upper and lower courses, there is a high variation between maximum and minimum peaks because the underdevelopment of the floodplain, while in the medium course the flow peaks are smoothed by the presence of a well-developed river floodplain. In this area, the river can lose up to 30% in water discharge, which is stored in the floodplain. Three types of flood categories were defined, and two mechanisms of flow storage and transfer were identified, explaining the discharge loss in the middle course. Three main mechanisms produce the water loss mid-course: the sponge effect of the alluvial plain, the existence of a well-developed mosaic of lakes, and an arboreal-dominated vegetation stratum of alluvial forest.Facultad de Ciencias Naturales y Muse

Caracterização hidrológica e geomorfológica dos afluentes da Bacia do Rio Araguaia

O conhecimento do comportamento hidrol&oacute;gico e geomorfol&oacute;gico da bacia do Araguaia t&ecirc;m avan&ccedil;ado significativamente nos &uacute;ltimos anos. Por&eacute;m, dados essenciais para o entendimento do sistema e para o planejamento de recursos h&iacute;dricos, como s&atilde;o as estimativas de aportes l&iacute;quidos anuais dos tribut&aacute;rios n&atilde;o foram obtidos. Neste artigo se organizou uma regionaliza&ccedil;&atilde;o baseada na geologia e geomorfologia dominantes das bacias dos afuentes, se caracterizou o funcionamento hidrol&oacute;gico geral dos mesmos e com as 11 esta&ccedil;&otilde;es dos tribut&aacute;rios dispon&iacute;veis para toda a bacia se calculou uma curva de correla&ccedil;&atilde;o entre as vari&aacute;veis &aacute;rea de drenagem e vaz&atilde;o. Devido &agrave; falta de esta&ccedil;&otilde;es fluviom&eacute;tricas no baixo curso dos afluentes, se estimaram os aportes l&iacute;quidos m&eacute;dios anuais dos mesmos por meio da utiliza&ccedil;&atilde;o de &aacute;rea de drenagem na foz dos tribut&aacute;rios. Foram calculados posteriormente, os aportes correspondentes para a alta, m&eacute;dia e baixa bacia. Estes valores estimados da curva foram confrontados com os dados existentes nas principais esta&ccedil;&otilde;es hidrol&oacute;gicas localizadas no canal principal do Araguaia (9 esta&ccedil;&otilde;es). O Alto curso tem uma representatividade de 10,4% do fluxo da bacia. O m&eacute;dio Araguaia contribui com 77,5% da descarga total e o baixo Araguaia contribui com 12,06% da vaz&atilde;o da bacia. A respeito da entrada por margens, os afluentes da margem esquerda contribuem com 179.363,88 km2 e uma vaz&Atilde;o m&eacute;dia anual de 2.785,13 m3/s enquanto os da margem direita aportam 3.223,28 m3/s de vaz&atilde;o m&eacute;dia anual drenando uma totalidade de 204.635,56 km2.</span

Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015 : a systematic analysis for the Global Burden of Disease Study 2015

Background Improving survival and extending the longevity of life for all populations requires timely, robust evidence on local mortality levels and trends. The Global Burden of Disease 2015 Study (GBD 2015) provides a comprehensive assessment of all-cause and cause-specific mortality for 249 causes in 195 countries and territories from 1980 to 2015. These results informed an in-depth investigation of observed and expected mortality patterns based on sociodemographic measures. Methods We estimated all-cause mortality by age, sex, geography, and year using an improved analytical approach originally developed for GBD 2013 and GBD 2010. Improvements included refinements to the estimation of child and adult mortality and corresponding uncertainty, parameter selection for under-5 mortality synthesis by spatiotemporal Gaussian process regression, and sibling history data processing. We also expanded the database of vital registration, survey, and census data to 14 294 geography-year datapoints. For GBD 2015, eight causes, including Ebola virus disease, were added to the previous GBD cause list for mortality. We used six modelling approaches to assess cause-specific mortality, with the Cause of Death Ensemble Model (CODEm) generating estimates for most causes. We used a series of novel analyses to systematically quantify the drivers of trends in mortality across geographies. First, we assessed observed and expected levels and trends of cause-specific mortality as they relate to the Socio-demographic Index (SDI), a summary indicator derived from measures of income per capita, educational attainment, and fertility. Second, we examined factors affecting total mortality patterns through a series of counterfactual scenarios, testing the magnitude by which population growth, population age structures, and epidemiological changes contributed to shifts in mortality. Finally, we attributed changes in life expectancy to changes in cause of death. We documented each step of the GBD 2015 estimation processes, as well as data sources, in accordance with Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER). Findings Globally, life expectancy from birth increased from 61.7 years (95% uncertainty interval 61.4-61.9) in 1980 to 71.8 years (71.5-72.2) in 2015. Several countries in sub-Saharan Africa had very large gains in life expectancy from 2005 to 2015, rebounding from an era of exceedingly high loss of life due to HIV/AIDS. At the same time, many geographies saw life expectancy stagnate or decline, particularly for men and in countries with rising mortality from war or interpersonal violence. From 2005 to 2015, male life expectancy in Syria dropped by 11.3 years (3.7-17.4), to 62.6 years (56.5-70.2). Total deaths increased by 4.1% (2.6-5.6) from 2005 to 2015, rising to 55.8 million (54.9 million to 56.6 million) in 2015, but age-standardised death rates fell by 17.0% (15.8-18.1) during this time, underscoring changes in population growth and shifts in global age structures. The result was similar for non-communicable diseases (NCDs), with total deaths from these causes increasing by 14.1% (12.6-16.0) to 39.8 million (39.2 million to 40.5 million) in 2015, whereas age-standardised rates decreased by 13.1% (11.9-14.3). Globally, this mortality pattern emerged for several NCDs, including several types of cancer, ischaemic heart disease, cirrhosis, and Alzheimer's disease and other dementias. By contrast, both total deaths and age-standardised death rates due to communicable, maternal, neonatal, and nutritional conditions significantly declined from 2005 to 2015, gains largely attributable to decreases in mortality rates due to HIV/AIDS (42.1%, 39.1-44.6), malaria (43.1%, 34.7-51.8), neonatal preterm birth complications (29.8%, 24.8-34.9), and maternal disorders (29.1%, 19.3-37.1). Progress was slower for several causes, such as lower respiratory infections and nutritional deficiencies, whereas deaths increased for others, including dengue and drug use disorders. Age-standardised death rates due to injuries significantly declined from 2005 to 2015, yet interpersonal violence and war claimed increasingly more lives in some regions, particularly in the Middle East. In 2015, rotaviral enteritis (rotavirus) was the leading cause of under-5 deaths due to diarrhoea (146 000 deaths, 118 000-183 000) and pneumococcal pneumonia was the leading cause of under-5 deaths due to lower respiratory infections (393 000 deaths, 228 000-532 000), although pathogen-specific mortality varied by region. Globally, the effects of population growth, ageing, and changes in age-standardised death rates substantially differed by cause. Our analyses on the expected associations between cause-specific mortality and SDI show the regular shifts in cause of death composition and population age structure with rising SDI. Country patterns of premature mortality (measured as years of life lost [YLLs]) and how they differ from the level expected on the basis of SDI alone revealed distinct but highly heterogeneous patterns by region and country or territory. Ischaemic heart disease, stroke, and diabetes were among the leading causes of YLLs in most regions, but in many cases, intraregional results sharply diverged for ratios of observed and expected YLLs based on SDI. Communicable, maternal, neonatal, and nutritional diseases caused the most YLLs throughout sub-Saharan Africa, with observed YLLs far exceeding expected YLLs for countries in which malaria or HIV/AIDS remained the leading causes of early death. Interpretation At the global scale, age-specific mortality has steadily improved over the past 35 years; this pattern of general progress continued in the past decade. Progress has been faster in most countries than expected on the basis of development measured by the SDI. Against this background of progress, some countries have seen falls in life expectancy, and age-standardised death rates for some causes are increasing. Despite progress in reducing age-standardised death rates, population growth and ageing mean that the number of deaths from most non-communicable causes are increasing in most countries, putting increased demands on health systems. Copyright (C) The Author(s). Published by Elsevier Ltd.Peer reviewe

Connectivity processes and riparian vegetation of the upper Paraná River, Brazil

In fluvial systems, the relationship between a dominant variable (e.g. flood pulse) and its dependent ones (e.g. riparian vegetation) is called connectivity. This paper analyzes the connectivity elements and processes controlling riparian vegetation for a reach of the upper Paraná River (Brazil) and estimates the future changes in channel-vegetation relationship as a consequence of the managing of a large dam. The studied reach is situated 30km downstream from the Porto Primavera Dam (construction finished in 1999). Through aerial photography (1:25,000, 1996), RGB-CBERS satellite imagery and a previous field botany survey it was possible to elaborate a map with the five major morpho-vegetation units: 1) Tree-dominated natural levee, 2) Shrubby upper floodplain, 3) Shrub-herbaceous mid floodplain, 4) Grass-herbaceous lower floodplain and 5) Shrub-herbaceous flood runoff channel units. By use of a detailed topographic survey and statistical tools each morpho-vegetation type was analyzed according to its connectivity parameters (frequency, recurrence, permanence, seasonality, potamophase, limnophase and FCQ index) in the pre- and post-dam closure periods of the historical series. Data showed that most of the morpho-vegetation units were predicted to present changes in connectivity parameters values after dam closing and the new regime could affect, in different intensity, the river ecology and particularly the riparian vegetation. The methods used in this study can be useful for dam impact studies in other South American tropical rivers. © 2012 Elsevier Ltd

<strong>Controles hidrogeomorfológicos nas unidades vegetacionais da planície aluvial do rio Araguaia, Brasil</strong> - DOI: 10.4025/actascibiolsci.v30i4.5871 <b>Hydro-geomorphologic controls in the vegetation of the Araguaia river floodplain, Brazil</b> - DOI: 10.4025/actascibiolsci.v30i4.5871

A existência de diferentes tipologias vegetais na planície aluvial do médio Araguaia apresenta um padrão de distribuição determinado pela dinâmica fluvial do canal e pelas características morfossedimentares das unidades que formam a planície aluvial. O objetivo deste trabalho foi discutir como a dinâmica fluvial atua nos processos de sucessão vegetacional, considerando os processos de erosão e deposição, dentro de um curto intervalo temporal, e a dinâmica de cheias. O processamento de informações dos mapas das unidades morfossedimentares da planície e das unidades vegetacionais resultou no mapa de unidades morfovegetacionais. Verificou-se que as unidades vegetacionais se distribuem e compõem, de modo diversificado, um mosaico vegetacional pela planície. Entre 1965 e 1997, a ação dos processos erosivos, nas margens do canal que consomem a planície aluvial, tem removido principalmente vegetações arbóreas de grande porte, e as altas taxas de sedimentação contribuem para a formação da unidade geomorfológica mais jovem da planície, que é colonizada, sobretudo, por espécies herbáceas.<br>The existence of different vegetable typologies in the alluvial plains of the middle Araguaia presents a pattern of distribution determined by the fluvial dynamic of the channel and the type of sediments that form different units of the alluvial plain. The purpose of this study was to discuss how the fluvial processes acts in vegetation succession, considering the erosive and sedimentary activities within a short period of time, as well as the flood dynamic. The combined information from morphosedimentary unit maps of the alluvial plain and the vegetation units allows the elaboration of the map of morphosedimentary units. It was possible to verify that the vegetation units were distributed in a diversified way along the alluvial plain, composing a vegetation mosaic. Between 1965 and 1997, the action of the erosive processes in the banks of the channel that consume the alluvial plain removed in particular large arboreal vegetation types, and the high rates of sedimentation contribute to the formation of the most recent geomorphologic unit of the plain, which is being colonized especially by herbaceous species