RESUMOVisa-se, neste trabalho, avaliar os dados Shuttle Radar Topography Mission (SRTM) na caracterização morfométrica de bacias hidrográficas, através da comparação das características obtidas a partir de dados SRTM e de cartas topográficas, processados em Sistema de Informação Geográfica (SIG). O estudo foi realizado tomando-se por base a bacia hidrográ-fica do Ribeirão Salobra, com área aproximada de 540 km 2 . A diferença percentual obtida nos dados morfométricos entre os métodos estudados foi inferior a 11%, exceto no índice de circularidade (22%) e declividade média (55%). A utilização de dados SRTM em ambiente SIG permite a caracterização morfométrica de bacias hidrográficas, podendo auxiliar a gestão e o gerenciamento dos recursos hídricos, mostrando-se uma alternativa prática e viável ao minimizar custos e tempo na execução dos trabalhos.
Palavras-chave: modelo digital de elevação, gestão de recursos hídricos, hidrologia
Morphometric characterization of watershed through SRTM data
ABSTRACTThis study aimed to evaluate the Shuttle Radar Topography Mission (SRTM) data in morphometric characterization of watersheds, through the comparison of the characteristics obtained from SRTM data and topographic letters, by using the Geographic Information System (GIS). The study considered the Ribeirão Salobra basin, its area is about 540 km 2 . The percentage difference in the morphometric data obtained between the two methods was less than 11%, except for the index of circularity (22%) and average slope (55%). The use of SRTM data allows the morphometric characterization of watershed and can help management of water resources. In addition, this is an easy and economic alternative to minimize costs and job times.
The time of concentration for a watershed is an essential parameter to the design of any hydrological project. In this study, a time of concentration estimation-model that uses variables obtained by monitoring rainfall-runoff events in a rural watershed of a tropical climate is proposed. In developing the model, the relationship between the time of concentration and independent variables was verified using a linear correlation matrix. Two variables with the highest correlation coefficient were selected to derive a model that can estimate the time of concentration. The Harmony Search (HS) optimization algorithm was employed to optimize the model parameters. The performance of the model was evaluated based on the Nash-Sutcliffe (NS) coefficient, which yielded a value greater than 0.80. The proposed model allows one to estimate the time of concentration using only the hydrograph of an event at the base level of a watershed, without the use of rainfall data.
Constructed wetlands systems demand preliminary and primary treatment to remove solids present in greywater (GW) to avoid or reduce clogging processes. The current paper aims to assess hydraulic and hydrological behavior in an improved constructed wetland system, which has a built-in anaerobic digestion chamber (AnC), GW is distributed to the evapotranspiration and treatment tank (CEvaT), combined with a subsurface horizontal flow constructed wetland (SSHF-CW). The results show that both the plants present in the units and the AnC improve hydraulic and volumetric efficiency, decrease short-circuiting and improve mixing conditions in the system. Moreover, the hydraulic conductivity measured on-site indicates that the presence of plants in the system and the flow distribution pattern provided by the AnC might reduce clogging in the SSHF-CW. It is observed that rainfall enables salt elimination, thus increasing evapotranspiration (ET), which promotes effluent reduction and enables the system to have zero discharge when reuse is unfeasible.
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