cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.5668492
title: A morphodynamic model for cohesive sediments transport

description: ABSTRACT The dynamics of cohesive sediments in natural water bodies is of great importance for coastal engineering. Quite often, it is necessary to assess sedimentological processes in regions where cohesive sediments are prevalent, such as in many harbors. Such assessments poses challenges, especially in quantitative evaluations, as the physics involved in the transport, sedimentation and erosion of cohesive sediments is rather complex. For that, by all means, it is important to have analysis tools capable of computing cohesive sediments dynamics. This paper presents the development of a vertically averaged eulerian transport model for suspended cohesive sediments. Such model is currently available on SisBaHiA®, which is a computational modeling system developed and maintained in COPPE/UFRJ. After describing the model implementation, we present a discussion on consistency and validation tests, for each implemented mechanism within the sedimentological process, with a focus in the erosion and sedimentation fluxes. In sequence, we compare model results with the theoretical results and, for some tests, with the results of the simulations performed with the Delft3D® and Telemac® modeling systems. These models are similar to the one presented in this paper, and are well accepted and widely used on professional projects and studies. The tests showed that the developed model results were consistent for all the evaluated mechanism, and hence it’s positively verified.
DOI: 10.6084/m9.figshare.5668492.v1
title: A morphodynamic model for cohesive sediments transport

description: ABSTRACT The dynamics of cohesive sediments in natural water bodies is of great importance for coastal engineering. Quite often, it is necessary to assess sedimentological processes in regions where cohesive sediments are prevalent, such as in many harbors. Such assessments poses challenges, especially in quantitative evaluations, as the physics involved in the transport, sedimentation and erosion of cohesive sediments is rather complex. For that, by all means, it is important to have analysis tools capable of computing cohesive sediments dynamics. This paper presents the development of a vertically averaged eulerian transport model for suspended cohesive sediments. Such model is currently available on SisBaHiA®, which is a computational modeling system developed and maintained in COPPE/UFRJ. After describing the model implementation, we present a discussion on consistency and validation tests, for each implemented mechanism within the sedimentological process, with a focus in the erosion and sedimentation fluxes. In sequence, we compare model results with the theoretical results and, for some tests, with the results of the simulations performed with the Delft3D® and Telemac® modeling systems. These models are similar to the one presented in this paper, and are well accepted and widely used on professional projects and studies. The tests showed that the developed model results were consistent for all the evaluated mechanism, and hence it’s positively verified.
DOI: 10.6084/m9.figshare.7512722
title: Regional envelope curves for the state of Ceará: a tool for verification of hydrological dam safety

description: ABSTRACT Envelope curves are important tools for preliminary evaluation of design floods, for sizing hydraulic structures and for checking the design peak discharge in old dams, to verify their hydrological safety. These curves, associated with a mathematical equation, determine the upper line that involves the maximum values of the floods associated with the respective basin areas. Envelope curves can be global or regional; maybe relative to maximum recorded floods or certain return periods. This paper presents a review of the various envelope curves developed in the world and, in addition, applies them to the hydrological conditions of the watersheds in Ceará. Three envelope curves widely used in the literature were tested. Based on the estimation of new regional parameters for Ceará, envelope curves for floods with Tr equal to 1.000 and 10.000 years were constructed for the State. For developing the envelope curves, 43 hydrological dams’ projects, designed by hydrological techniques adopted by state water resources institutions, were investigated.
DOI: 10.6084/m9.figshare.7512722.v1
title: Regional envelope curves for the state of Ceará: a tool for verification of hydrological dam safety

description: ABSTRACT Envelope curves are important tools for preliminary evaluation of design floods, for sizing hydraulic structures and for checking the design peak discharge in old dams, to verify their hydrological safety. These curves, associated with a mathematical equation, determine the upper line that involves the maximum values of the floods associated with the respective basin areas. Envelope curves can be global or regional; maybe relative to maximum recorded floods or certain return periods. This paper presents a review of the various envelope curves developed in the world and, in addition, applies them to the hydrological conditions of the watersheds in Ceará. Three envelope curves widely used in the literature were tested. Based on the estimation of new regional parameters for Ceará, envelope curves for floods with Tr equal to 1.000 and 10.000 years were constructed for the State. For developing the envelope curves, 43 hydrological dams’ projects, designed by hydrological techniques adopted by state water resources institutions, were investigated.
DOI: 10.6084/m9.figshare.5721064
title: An alternative method for measuring velocities in open-channel flows: perfomance evaluation of a Pitot tube compared to an acoustic meter

description: ABSTRACT Hydrometric measurements undertaken in channels with high velocities are conditioned to the particularities of the flow, which is often characterized by instantaneous fluctuations and disturbances on the free surface. In such cases, the uncertainties associated with velocity fluctuations exceed the precision offered by the instruments that are employed in conventional techniques. A reasonable accuracy of the results is therefore sufficient to accomplish the objective of the measurements. The use of devices based on Pitot’s principle in fast open-channel flows could be an effective alternative to conventional velocity meters. This study aimed to develop a Pitot tube in its simplest configuration and evaluate its performance in a laboratory channel at velocities ranging from 0.2 to 2.0 m/s. The uncertainties in the static and total head readings were propagated to the output velocities, showing that the device built has the potential for measurements over 1.2 m/s, but it is not recommended for low velocities (&lt;0.6 m/s). The results were compared to those taken using an Acoustic Doppler Velocimeter (ADV). The instantaneous velocity readings indicated uncertainties of the same order of magnitude in both instruments. The differences between the mean velocities measured by the Pitot tube and the ADV were restricted to an agreement range of 15%, which is expected to be gradually reduced with further increase in flow velocity. The results showed the similar performances of both devices regarding the higher velocity estimates. Therefore, velocity meters should be developed to employ Pitot devices as an alternative method in high-velocity open-channel flows.
DOI: 10.6084/m9.figshare.5721064.v1
title: An alternative method for measuring velocities in open-channel flows: perfomance evaluation of a Pitot tube compared to an acoustic meter

description: ABSTRACT Hydrometric measurements undertaken in channels with high velocities are conditioned to the particularities of the flow, which is often characterized by instantaneous fluctuations and disturbances on the free surface. In such cases, the uncertainties associated with velocity fluctuations exceed the precision offered by the instruments that are employed in conventional techniques. A reasonable accuracy of the results is therefore sufficient to accomplish the objective of the measurements. The use of devices based on Pitot’s principle in fast open-channel flows could be an effective alternative to conventional velocity meters. This study aimed to develop a Pitot tube in its simplest configuration and evaluate its performance in a laboratory channel at velocities ranging from 0.2 to 2.0 m/s. The uncertainties in the static and total head readings were propagated to the output velocities, showing that the device built has the potential for measurements over 1.2 m/s, but it is not recommended for low velocities (&lt;0.6 m/s). The results were compared to those taken using an Acoustic Doppler Velocimeter (ADV). The instantaneous velocity readings indicated uncertainties of the same order of magnitude in both instruments. The differences between the mean velocities measured by the Pitot tube and the ADV were restricted to an agreement range of 15%, which is expected to be gradually reduced with further increase in flow velocity. The results showed the similar performances of both devices regarding the higher velocity estimates. Therefore, velocity meters should be developed to employ Pitot devices as an alternative method in high-velocity open-channel flows.
DOI: 10.6084/m9.figshare.7512707
title: Preliminary estimate of floods discharge in Brazil using Creager envelope curves

description: ABSTRACT Hydrologic studies are essential for the design and safety of hydraulic structures. In the past, a number of empirical equations were developed to represent relationships between drainage areas and observed peak discharges. Although these empirical equations have not been used frequently to study peak discharges due to the use of more detailed and sophisticated analysis, they can be used to estimate reference values, especially in ungaged sites. The objective of this paper is to assess peak discharges observed in many regions in Brazil, estimate the 10,000-year discharges according the Guia para Cálculo de Cheia de Projeto de Vertedores from Eletrobrás and compare them to the Creager envelope curves. In this study we used the records of naturalized discharges for the period of 1931 to 2012, for 131 hydroelectric projects selected in the main river basins in Brazil, using the official data published by the Operador Nacional do Sistema Elétrico (ONS) for the Sistema Interligado Nacional (SIN). The results presented in this paper show that it is possible to use the Creager envelope curves as a preliminary estimate of the design floods in Brazil. Generally, values of the Greager C coefficient between 60 and 100 are recommended for a preliminary estimate of a range of maximum discharges within drainage areas bigger than 10,000 km2. The results can be used in the preliminary estimate of maximum discharges and 10,000-year discharges for sites with no data using C values obtained from areas with enough data in the same river basin and with similar physical characteristics.
DOI: 10.6084/m9.figshare.7512707.v1
title: Preliminary estimate of floods discharge in Brazil using Creager envelope curves

description: ABSTRACT Hydrologic studies are essential for the design and safety of hydraulic structures. In the past, a number of empirical equations were developed to represent relationships between drainage areas and observed peak discharges. Although these empirical equations have not been used frequently to study peak discharges due to the use of more detailed and sophisticated analysis, they can be used to estimate reference values, especially in ungaged sites. The objective of this paper is to assess peak discharges observed in many regions in Brazil, estimate the 10,000-year discharges according the Guia para Cálculo de Cheia de Projeto de Vertedores from Eletrobrás and compare them to the Creager envelope curves. In this study we used the records of naturalized discharges for the period of 1931 to 2012, for 131 hydroelectric projects selected in the main river basins in Brazil, using the official data published by the Operador Nacional do Sistema Elétrico (ONS) for the Sistema Interligado Nacional (SIN). The results presented in this paper show that it is possible to use the Creager envelope curves as a preliminary estimate of the design floods in Brazil. Generally, values of the Greager C coefficient between 60 and 100 are recommended for a preliminary estimate of a range of maximum discharges within drainage areas bigger than 10,000 km2. The results can be used in the preliminary estimate of maximum discharges and 10,000-year discharges for sites with no data using C values obtained from areas with enough data in the same river basin and with similar physical characteristics.
DOI: 10.6084/m9.figshare.6151727
title: Precipitation anomalies in the Brazilian southern coast related to the SAM and ENSO climate variability modes

description: ABSTRACT The precipitation pattern of the State of Rio Grande do Sul (RS) is changing, indicating an increase, although there are long periods of drought. Several studies indicate the influence of climate variability modes on RS precipitation. This work analyzes the influence of the Southern Annular Mode (SAM) and the El Niño - Southern Oscillation (ENSO) on precipitation anomalies (PP) of the Rio Grande do Sul Coastal Plain (RGSCP), dividing it into three regions: south, central and north. Contingency tables were used to correlate the indices, classifying them as neutral, below ou above the mean. To statistical significance we used percentage correctly classified with which the Student’s t was aplied for each region. The PP of the RGSCP and the south coast have correlation with the ENSO and SAM; the central only with SAM. The PP of the north is not correlated to either index. Periods with more than 5 months of PP, SAM and ENSO anomalies were identified. Below average events were majority. The results indicate greater influence of SAM + and La Niña. The trend towards SAM+ and intensification of ENSO, could increase the frequency of droughts in RGSCP. In addition, it was possible to interpret that the geographical differences of the RGSCP can influence the results of precipitation totals. This work contributes to the understanding of the effects of the new trends of climatic variability under regional and geographical aspects.
DOI: 10.6084/m9.figshare.6151727.v1
title: Precipitation anomalies in the Brazilian southern coast related to the SAM and ENSO climate variability modes

description: ABSTRACT The precipitation pattern of the State of Rio Grande do Sul (RS) is changing, indicating an increase, although there are long periods of drought. Several studies indicate the influence of climate variability modes on RS precipitation. This work analyzes the influence of the Southern Annular Mode (SAM) and the El Niño - Southern Oscillation (ENSO) on precipitation anomalies (PP) of the Rio Grande do Sul Coastal Plain (RGSCP), dividing it into three regions: south, central and north. Contingency tables were used to correlate the indices, classifying them as neutral, below ou above the mean. To statistical significance we used percentage correctly classified with which the Student’s t was aplied for each region. The PP of the RGSCP and the south coast have correlation with the ENSO and SAM; the central only with SAM. The PP of the north is not correlated to either index. Periods with more than 5 months of PP, SAM and ENSO anomalies were identified. Below average events were majority. The results indicate greater influence of SAM + and La Niña. The trend towards SAM+ and intensification of ENSO, could increase the frequency of droughts in RGSCP. In addition, it was possible to interpret that the geographical differences of the RGSCP can influence the results of precipitation totals. This work contributes to the understanding of the effects of the new trends of climatic variability under regional and geographical aspects.
DOI: 10.6084/m9.figshare.5980063
title: Comparison of numerical schemes of river flood routing with an inertial approximation of the Saint Venant equations

description: ABSTRACT The one-dimensional flow routing inertial model, formulated as an explicit solution, has advantages over other explicit models used in hydrological models that simplify the Saint-Venant equations. The main advantage is a simple formulation with good results. However, the inertial model is restricted to a small time step to avoid numerical instability. This paper proposes six numerical schemes that modify the one-dimensional inertial model in order to increase the numerical stability of the solution. The proposed numerical schemes were compared to the original scheme in four situations of river’s slope (normal, low, high and very high) and in two situations where the river is subject to downstream effects (dam backwater and tides). The results are discussed in terms of stability, peak flow, processing time, volume conservation error and RMSE (Root Mean Square Error). In general, the schemes showed improvement relative to each type of application. In particular, the numerical scheme here called Prog Q(k+1)xQ(k+1) stood out presenting advantages with greater numerical stability in relation to the original scheme. However, this scheme was not successful in the tide simulation situation. In addition, it was observed that the inclusion of the hydraulic radius calculation without simplification in the numerical schemes improved the results without increasing the computational time.
DOI: 10.6084/m9.figshare.5980063.v1
title: Comparison of numerical schemes of river flood routing with an inertial approximation of the Saint Venant equations

description: ABSTRACT The one-dimensional flow routing inertial model, formulated as an explicit solution, has advantages over other explicit models used in hydrological models that simplify the Saint-Venant equations. The main advantage is a simple formulation with good results. However, the inertial model is restricted to a small time step to avoid numerical instability. This paper proposes six numerical schemes that modify the one-dimensional inertial model in order to increase the numerical stability of the solution. The proposed numerical schemes were compared to the original scheme in four situations of river’s slope (normal, low, high and very high) and in two situations where the river is subject to downstream effects (dam backwater and tides). The results are discussed in terms of stability, peak flow, processing time, volume conservation error and RMSE (Root Mean Square Error). In general, the schemes showed improvement relative to each type of application. In particular, the numerical scheme here called Prog Q(k+1)xQ(k+1) stood out presenting advantages with greater numerical stability in relation to the original scheme. However, this scheme was not successful in the tide simulation situation. In addition, it was observed that the inclusion of the hydraulic radius calculation without simplification in the numerical schemes improved the results without increasing the computational time.
DOI: 10.6084/m9.figshare.6448343
title: Wastewater treatment systems selection inside watersheds by using multiobjective analysis

description: ABSTRACT In order to determine required wastewater treatment plants (WWTP’s) efficiencies, several methodologies have been proposed to assist the sewage treatment systems process selection, usually aiming to achieve economic objectives. However, in water resources problems solving, search involves multiple and conflicting objectives. This work used, for Pardo’s river basin (Espírito Santo State, Brazil), water quality simulation model, optimization technique and multiobjective analysis for selecting sewage treatment systems, taking into account Brazilian environmental effluents Biochemical Oxygen Demand standards, imposed by CONAMA Resolution 430/2011. After proposing an optimization model that allowed the estimation of minimum organic matter removal efficiencies, a multiobjective analysis was applied by using the ELECTRE III method, which selected sewage treatment systems for localities responsible for domestic wastewater disposal in Pardo’s river basin. The results indicated that keeping the effluents standards can produce treatment plants overestimation and inadequate allocated financial resources distribution for sewage treatment plants implementation. Treatment systems such as Submerged Aerated Biofilters (with Nitrification), Wetlands and Facultative Ponds were the most selected, considering different contexts appreciated in this work.
DOI: 10.6084/m9.figshare.6448343.v1
title: Wastewater treatment systems selection inside watersheds by using multiobjective analysis

description: ABSTRACT In order to determine required wastewater treatment plants (WWTP’s) efficiencies, several methodologies have been proposed to assist the sewage treatment systems process selection, usually aiming to achieve economic objectives. However, in water resources problems solving, search involves multiple and conflicting objectives. This work used, for Pardo’s river basin (Espírito Santo State, Brazil), water quality simulation model, optimization technique and multiobjective analysis for selecting sewage treatment systems, taking into account Brazilian environmental effluents Biochemical Oxygen Demand standards, imposed by CONAMA Resolution 430/2011. After proposing an optimization model that allowed the estimation of minimum organic matter removal efficiencies, a multiobjective analysis was applied by using the ELECTRE III method, which selected sewage treatment systems for localities responsible for domestic wastewater disposal in Pardo’s river basin. The results indicated that keeping the effluents standards can produce treatment plants overestimation and inadequate allocated financial resources distribution for sewage treatment plants implementation. Treatment systems such as Submerged Aerated Biofilters (with Nitrification), Wetlands and Facultative Ponds were the most selected, considering different contexts appreciated in this work.
DOI: 10.6084/m9.figshare.7507058
title: Wind-induced internal seiches in Vossoroca reservoir, PR, Brazil

description: ABSTRACT The vertical movements caused by internal waves in lakes and reservoirs have chemical and biological consequences for these ecosystems. The vast majority of studies that investigate internal waves are conducted on large lakes. There are just few researches that investigate this phenomenon on dendritic reservoirs. The purpose of this research was to identify internal waves (baroclinic mode) in the Vossoroca reservoir by using temperature time series recorded between May to November 2012. A two-layer method was used which considered rigid upper and lower boundaries. Moreover, the potential flow theory was used for both layers since the flow within each layer was considered irrotational. From the dispersion relation, we obtained the theoretical shallow internal wave period. The power spectral density (PSD) of temperature series of thermocline depth, provided by fast Fourier transform, helped in the identification on the frequency peak. Subsequently, the theoretical period was compared with the frequency spectra. Using a careful analysis (excluding the interference of solar radiation and intensity of wind), we observed a clear peak in November due to an internal wave with period around 8 hours, which matched the theoretical calculation from the dispersion relation equation for V1H1 mode. Weak winds from southwest excited a V1H1 baroclinic mode. According to spectral analysis, after the passage of this long-basin internal seiches, we identified the formation of higher vertical internal seiche modes. In addition, we observe indications of V1H1 mode degeneration.