Floods that occur in hydrographic basins with high slopes are more susceptible to natural hazards due to the occurrence of high intensity hydrological events and the type of sloping relief. These two associated factors contribute to an increase in the destructive potential of these regions, causing economic damage and loss of life for people and animals. This study sought to assess the floodplain areas in the Canoas, Sertão, and Mampituba Rivers that contribute to the Mampituba River basin in southern Brazil, to support emergency procedures for dealing with floods and contribute to the territorial management of these spaces. From the hydrological data of the Mampituba River basin, a hydrological model was used, which generated flows that were inserted as input to a hydrodynamic model, resulting in flood patches in the plains of the modeled rivers. The calibration and integration studies of the models were carried out on a computational platform that employs the hydrometeorological knowledge represented by the models of the basin under study. The hydrodynamic modeling represented in the maps indicated that the flooding patches occur within the river channels and in the plains occupied by agriculture, with a predominance of irrigated rice paddies, pasture fields, forestry, urbanized areas, and native vegetation. In the urban region along the floodplains of the Praia Grande and Mampituba Cities, there are inns, restaurants, and residences which can suffer structural damage and expose people to the danger of a flood event of this magnitude. The results achieved allow us to infer that the integrated modeling system proved to be capable of performing efficient hydrological and hydrodynamic simulations. The methods used can be replicated in other basins and the results can support public managers for greater assertiveness in decision-making when facing the dangers of extreme weather events.
A representação do processo precipitação-vazão por meio de modelos hidrológicos conceituais visa quantificar o volume escoado em uma bacia como consequência de uma determinada precipitação. Aliados a eles, os índices têm sido uma ferramenta útil para quantificar eventos extremos, como o Soil Moisture Index (TMI) que foi formulado a partir do modelo hidrológico Tank Model. Desta forma, o objetivo deste trabalho foi aplicar o Tank Model para a bacia do rio Perdizes, em Cambará do Sul (RS), e avaliar o desempenho do TMI para prever a ocorrência de cheias, limiar este utilizado para o fechamento da Trilha do rio do Boi, no Parque Nacional de Aparados da Serra (PNAS). Os dados utilizados na simulação foram obtidos pelas estações meteorológica e fluviométrica instaladas na bacia. Após a calibração e validação de três séries históricas no Tank Model, os valores obtidos do TMI foram comparados com os dias que a Trilha foi fechada, a partir de altos níveis registrados no rio Perdizes. O TMI demonstrou que o nível utilizado para fechar a Trilha do rio do Boi correspondeu a cheias em 72% das vezes. Portanto, o TMI mostrou bom desempenho ao indicar a ocorrência de cheias na área estudada, sendo uma ferramenta útil para a tomada de decisões na gestão do PNAS. Application of the Tank Model as a Management Tool in the Perdizes River Basin - Cambará do Sul/RS.ABSTRACTThe representation of the rainfall-runoff process by means of conceptual hydrological models aims to quantify the volume drained in a basin as result of a specific precipitation. Allied to them, the indices have been a useful tool to quantify extreme events, such as the Tank Moisture Index (TMI) which was formulated from the Tank Model. Thus, the objective of this work was to apply the Tank Model to the Perdizes river basin, in Cambará do Sul (RS), and to evaluate the performance of the TMI to predict the occurrence of floods, the threshold used for the closure of the Rio do Boi trail, in the Aparados da Serra National Park (PNAS). The data used in the simulation were obtained at the meteorological and fluviometric stations installed in the basin. After the calibration and validation of three historical series in the Tank Model, the values obtained in the TMI were compared with the days when the Trail was closed, from high levels recorded in the Perdizes river. The average TMI values demonstrated that the level used to close the Rio do Boi Trail corresponded to floods 72% of the time, and the median, 75%. Therefore, the TMI showed good performance in indicating the occurrence of floods in the study area, being a useful tool for decision making in the PNAS management.Keywords: Tank Moisture Index, trail closure, Aparados da Serra National Park.
A ocupação sem planejamento da Zona Costeira tem promovido a substituição do ambiente natural original pelo ambiente antrópico, cuja implantação apresenta condições que desequilibram a Diversidade Ambiental (naturezas abiótica e biótica) e prejudicam o próprio ambiente antrópico. Essa problemática tende a continuar e se agravar em municípios pequenos, como é o caso de Jaguaruna/SC. O presente trabalho apresenta o método de estruturação das primeiras etapas de um planejamento estratégico costeiro desenvolvido no balneário Camacho/Jaguaruna por meio de ações e cenários de manejo baseados no mapeamento de condições de conflito, na aplicação do Índice de Criticidade Legal-Ambiental (ICLA), no paradigma da Geodiversidade e na dinâmica sedimentar. Em ambiente de Sistema de Informações Geográficas, foi realizada a regionalização paisagística da Diversidade Ambiental pelo cruzamento de informações das naturezas abiótica e biótica. Após a identificação e a hierarquização das principais condições de conflitos pela aplicação do ICLA, cada condição de conflito com área superior a 1.000 m2 foi avaliada. Foram encontradas 71 condições de conflito, as quais abrangem 79,91% das zonas ocupadas com atividades urbanas ou agrícolas. Ao confrontar os resultados com os instrumentos de gestão vigentes, as principais restrições observadas foram: desrespeito a condicionantes legais e ambientais de ocupação; saneamento básico deficiente; macrozoneamento e zoneamento urbano incoerentes com a dinâmica socioespacial do município; falta de investimento financeiro; e corpo técnico insuficiente. Os cenários de manejo permitiram projetar três tipos diferentes de intervenção (de médio prazo), que refletem distintas propostas de desenvolvimento, para deliberação e implementação por parte dos gestores públicos. A proposta metodológica, aliada à incorporação de diretrizes de outros instrumentos de gestão preexistentes, proporcionou: a identificação e a hierarquização de condições de conflito de forma simples e inteligível; a proposição de ações de manejo objetivas; a espacialização de cenários tendência e a continuidade de iniciativas de gestão preexistentes.
Resumo:O Cabo de Santa Marta (Laguna/SC) marca uma brusca mudança na orientação do litoral sul do Brasil. O vento NE é predominante ao longo do ano e incide da terra para o mar nas praias ao sul do cabo, o que representa um fator de entrada de sedimentos no sistema praial, juntamente com o aporte pela deriva litorânea e a contribuição continental da drenagem da região. No presente trabalho propõe-se uma análise integrada da dinâmica sedimentar na porção emersa e submersa das praias da Cigana e do Cardoso, através da; (i) caracterização do clima de ventos e o potencial de deriva eólica na região; (ii) análise das mudanças históricas no campo de dunas e na linha de costa; e (iii) avaliação do regime de ondas e transporte sedimentar pela deriva litorânea. Os resultados demonstraram uma
A comparison of methodologies was carried out to develop an operational flow forecasting system for a mountainous basin. The case studied was the Boi river, which is located in a small mountainous watershed in southern Brazil. This watershed is part of a conservation unit well known for the ecotourism activities carried out in that place. Among the activities, the Boi river trail can be highlighted, which is carried out following the riverbed. For this reason, the development of an alert system for this basin can help in determining the trail's closure in situations where the water flow is strong and could present risks to tourists safety. Thereby, two different scenarios were considered for the development of the forecasting system. First, the flow forecasts were performed using SOPREVA and considered a horizon of 1 day (short term forecasts). The second scenario considered medium-term forecasts (1 to 10 days horizon) and utilized the HEC-RTS as a basis for developing the forecast system. In both cases, the forecasts were based on the ensemble precipitation estimates of GEFS. The obtained results showed that the actual alarm rates were 0.77 and 0.86 for SOPREVA and HEC-RTS, respectively, when considering a horizon of one day in advance. The evaluation of the medium-term forecasts presented good results of this system for horizons up to 3 days in advance. Finally, the results of both considered scenarios showed that the systems could be used as a basis for management of the Boi river trail.
<p>Trails are one of the main places for ecotourism practitioners&#8217; activities. Many of them are located close to watercourses, and it is often necessary for practitioners to cross them. This often leads to dangerous situations, since critical conditions of water stages and flow velocity can make people lose their walking stability. One way to quantify these hazards is the hazard index (HI) which, in general, is defined as the product of the flow velocity by its depth (Stephenson, 2002). Although many studies have been carried out to determine the HI values as safety limits for people exposed to water flows, none of them analyzed the natural river conditions like those encountered during an ecotourism trail. In these environments, locomotion is hampered due to the surface which is usually highly irregular and often contains slippery rocks and sediments. Thus, that there is a gap related to the HI analysis in natural rivers, and more research becomes necessary, since more people have sought to carry out activities related to ecotourism. The main objective of this research is to apply HI approach in natural rivers so that its results can be utilized in the management of trails containing watercourses crossing. Initially, a bibliographic review was carried out, where some important concerns related to people's loss of stability were analyzed. The results of the bibliographic review were organized within a summary table which permits verifying variables with stronger influence on people's stability, during these walks. After this first stage, three mountain trails located in the Aparados da Serra National Park, in southern Brazil, were selected for field measurements. In all of these trails, measurements of flow depth and velocity were carried out using a small current meter and the granulometry of the river sediments was measured through an adaptation of the Pebble Count method. The measurements were taken at all points where tourists cross the riverbed during the trails, i.e., 23 measurement sites in total. The analysis of these data resulted in preliminar information: (i) an easy-to-interpret diagram that indicates the thresholds values of HI in natural rivers, named Hazard Index Diagram of Natural River (HIDNR); and (ii) list of the main variables responsible for people's loss of stability, in order to contribute to the safety of ecotourism practitioners. One of the next steps of the work is to analyze how the sediment transport and connectivity behaviour could give us insights about hazard levels.</p> <p>REFERENCES</p> <p>STEPHENSON, D. (2002). Integrated flood plain management strategy for the Vaal.&#160;Urban Water, v. 4, n. 4, p. 423-428.</p>
Current forecasts estimate that almost 68% of the global population will be living in urban centers by 2050. As a result, the increase in impermeable surface area can result in severe hydrological impacts, such as the increase in surface runoff and the frequency of floods and their magnitude. Thus, this work analyzes the performance of the hydrodynamic model HEC-RAS for assessing the extent of flood-prone areas, using two digital terrain models (DTM) with different spatial resolutions (5 and 0.50 m). Four different computing intervals (1, 15, 30, and 60 s) were adopted aiming to evaluate the simulations outputs performance. Additionally, reported data by the civil defense are used for calibration and validation. In general, the model showed to be a powerful tool in the identification of susceptible areas to urban flooding. The simulated results in this work provide crucial geographic information when identifying spots with the highest risk of flooding, which should receive priority attention during such events. The simulations with a spatial resolution of 5 m showed the flood maps with the largest coverage of the flooded points (278 points out of 286—97.20%), within the shortest computation times. We highlight that the more refined DTM derived from spatial images did not produce the best flood simulation compared to the DTM with a spatial resolution of 5 m derived from orthoimages.
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