Pub Date : 2021-01-01DOI: 10.1590/2318-0331.262120210057
Mayara Francisca da Silva, F. V. Gonçalves, J. Janzen
ABSTRACT Computational Fluid Dynamics (CFD) simulations of a leakage in a pressurized pipe were undertaken to determine the empirical effects of hydraulic and geometric factors on the leakage flow rate. The results showed that pressure, leakage area and leakage form, influenced the leakage flow rate significantly, while pipe thickness and mean velocity did not influence the leakage flow rate. With relation to the interactions, the effect of pressure upon leakage flow rate depends on leakage area, being stronger for great leakage areas; the effects of leakage area and pressure on leakage flow rate is more pronounced for longitudinal leakages than for circular leakages. Finally, our results suggest that the equations that predict leakage flow rate in pressurized pipes may need a revision.
{"title":"Effect of hydraulic and geometric factors upon leakage flow rate in pressurized pipes","authors":"Mayara Francisca da Silva, F. V. Gonçalves, J. Janzen","doi":"10.1590/2318-0331.262120210057","DOIUrl":"https://doi.org/10.1590/2318-0331.262120210057","url":null,"abstract":"ABSTRACT Computational Fluid Dynamics (CFD) simulations of a leakage in a pressurized pipe were undertaken to determine the empirical effects of hydraulic and geometric factors on the leakage flow rate. The results showed that pressure, leakage area and leakage form, influenced the leakage flow rate significantly, while pipe thickness and mean velocity did not influence the leakage flow rate. With relation to the interactions, the effect of pressure upon leakage flow rate depends on leakage area, being stronger for great leakage areas; the effects of leakage area and pressure on leakage flow rate is more pronounced for longitudinal leakages than for circular leakages. Finally, our results suggest that the equations that predict leakage flow rate in pressurized pipes may need a revision.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"10 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78140698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1590/2318-0331.262120210097
D. Santos, Jonathan Gonçalves da Silva, V. Becker
ABSTRACT Eutrophication is a global problem and an important cause of the ecological health degradation of aquatic ecosystems. The aim was to evaluate the effect of prolonged drought period (2012 to 2019) on the trophic state of two Brazilian semi-arid reservoirs, Boqueirão de Parelhas (BOQ) and Passagem das Traíras (TRA). The work was carried out according to a drought classification system, based on the Standardized Precipitation Index (SPI), with an aggregated timescale of 36 months, defining three periods. In the Period I, higher values of Secchi and lower values of turbidity, solids, nutrients and chlorophyll-a were registered, when compared to the other periods, mainly in BOQ. The principal component analyses of both reservoirs reveled a showed a temporal trend of the sample units according to the consequences of the prolonged drought. The results indicated changes in limnological variables due to the reduction of accumulated water volume, and they demonstrated that prolonged droughts impact the intensification of eutrophication in both systems. The trophic state of the BOQ reservoir was changed from mesotrophic to eutrophic as a consequence of the drought, while in TRA the eutrophic state remained, but with more intensified symptoms, with higher concentration values of nutrients, solids and algal biomass.
富营养化是一个全球性问题，是导致水生生态系统生态健康退化的重要原因。目的是评估长期干旱期(2012年至2019年)对巴西两个半干旱水库boqueir o de Parelhas (BOQ)和Passagem das Traíras (TRA)营养状态的影响。这项工作是根据基于标准化降水指数(SPI)的干旱分类系统进行的，总时间尺度为36个月，确定了三个时期。与其他时期相比，第1阶段Secchi值较高，浊度、固形物、营养物质和叶绿素-a值较低，主要表现在BOQ上。两个水库的主成分分析揭示了长期干旱影响下样本单元的时间变化趋势。结果表明，由于累积水量的减少，湖泊变量发生了变化，并表明长期干旱影响了两个系统的富营养化加剧。干旱导致BOQ水库的营养状态由中营养化向富营养化转变，而TRA水库的富营养化状态仍然存在，但症状更加严重，营养物、固体和藻类生物量的浓度值更高。
{"title":"Increasy eutrophication symptoms during a prolonged drought event in tropical semi-arid reservoirs, Brazil","authors":"D. Santos, Jonathan Gonçalves da Silva, V. Becker","doi":"10.1590/2318-0331.262120210097","DOIUrl":"https://doi.org/10.1590/2318-0331.262120210097","url":null,"abstract":"ABSTRACT Eutrophication is a global problem and an important cause of the ecological health degradation of aquatic ecosystems. The aim was to evaluate the effect of prolonged drought period (2012 to 2019) on the trophic state of two Brazilian semi-arid reservoirs, Boqueirão de Parelhas (BOQ) and Passagem das Traíras (TRA). The work was carried out according to a drought classification system, based on the Standardized Precipitation Index (SPI), with an aggregated timescale of 36 months, defining three periods. In the Period I, higher values of Secchi and lower values of turbidity, solids, nutrients and chlorophyll-a were registered, when compared to the other periods, mainly in BOQ. The principal component analyses of both reservoirs reveled a showed a temporal trend of the sample units according to the consequences of the prolonged drought. The results indicated changes in limnological variables due to the reduction of accumulated water volume, and they demonstrated that prolonged droughts impact the intensification of eutrophication in both systems. The trophic state of the BOQ reservoir was changed from mesotrophic to eutrophic as a consequence of the drought, while in TRA the eutrophic state remained, but with more intensified symptoms, with higher concentration values of nutrients, solids and algal biomass.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"270 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76280666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-18DOI: 10.1590/2318-0331.252020190050
J.M.A. Almeida, J. Ota
ABSTRACT This paper presents a comparative study between results obtained in two-dimensional computational simulations performed with three different turbulence models: constant viscosity; Elder Model and k˗Ꜫ Model. The simulations were performed using the software Telemac 2D. These results were compared to data obtained from a study in experimental channel with trapezoidal cross-section and composed of straight stretches and curves. The main objective of this comparison is to explore how turbulence models affect the general behavior of the simulated flow. To support these comparisons, statistical analysis were adopted to quantify the differences between the velocity fields obtained in the simulations and that observed in the experimental channel. The results showed that, despite the theoretical limitations, the use of the simpler turbulence closure model, that is the constant turbulent viscosity, can lead to results as good as or better than those obtained with more sophisticated models.
{"title":"Comparative study between turbulence models in curved channels","authors":"J.M.A. Almeida, J. Ota","doi":"10.1590/2318-0331.252020190050","DOIUrl":"https://doi.org/10.1590/2318-0331.252020190050","url":null,"abstract":"ABSTRACT This paper presents a comparative study between results obtained in two-dimensional computational simulations performed with three different turbulence models: constant viscosity; Elder Model and k˗Ꜫ Model. The simulations were performed using the software Telemac 2D. These results were compared to data obtained from a study in experimental channel with trapezoidal cross-section and composed of straight stretches and curves. The main objective of this comparison is to explore how turbulence models affect the general behavior of the simulated flow. To support these comparisons, statistical analysis were adopted to quantify the differences between the velocity fields obtained in the simulations and that observed in the experimental channel. The results showed that, despite the theoretical limitations, the use of the simpler turbulence closure model, that is the constant turbulent viscosity, can lead to results as good as or better than those obtained with more sophisticated models.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"39 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78740127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-17DOI: 10.1590/2318-0331.252020180023
D. S. Moura, Antonia Samylla Oliveira De Almeida, Carlos J. Pestana, Laura Gomes Girão, José Capelo-Neto
ABSTRACT Sediments are important to nutrient dynamics, especially due to phosphorus internal loading. Several studies have observed that internal loading could prevent water quality from improving in lakes, even when external phosphorus loading is significantly decreased. Therefore, there is an urgent need to assess the potential release of phosphorus contained in the sediment, and thus, its potential to impact water quality. In this study, the vertical and horizontal distributions of distinct phosphorus forms in the bottom sediments of artificial reservoirs, located at Forquilha watershed (Ceará, Brazil), were investigated through sequential chemical fractionation. The reservoirs Lagoa Cercada (R#1), Riacho do Algodão (R#2), Riacho Verde (R#3), Cachoeira (R#4), Chagas Manu (R#5), Quandu (R#6) and Balanças (R#7) were investigated. Reservoirs R#1 (most downstream reservoir of the watershed) and R#7 (most upstream reservoir of the watershed) had higher concentrations of total phosphorus (PT) and lower pH values, potentially exerting greater influence in phosphorus concentration in the water column. Reservoirs R#3 and R#4 presented a predominance of residual phosphorus (PRe), the least available fractions of phosphorus and thus, presented a lower potential for internal loading. Reservoirs R#5, R#1 and R#2 showed a tendency of decreasing total phosphorus (PT) as the sediment depth increased, probably indicating an increase of allochthonous phosphorus loading along time. Reservoir R#6 showed the predominance of PFeAl and PCa fractions on points A and B, respectively, showing that the characteristics of the sediments may vary in the same reservoir. Mobile (PM) and iron and aluminum-bound phosphorus (PFeAl) were the least and the most abundant fractions in most of the samples analyzed, respectively.
沉积物对养分动态非常重要，特别是磷的内部负荷。一些研究已经观察到，即使外部磷负荷显著减少，内部负荷也会阻止湖泊水质的改善。因此，迫切需要评估沉积物中所含磷的潜在释放，从而评估其对水质的潜在影响。在这项研究中，通过顺序化学分馏研究了位于Forquilha流域(ceearha)人工水库底部沉积物中不同形态磷的垂直和水平分布。对Lagoa Cercada (r# 1)、Riacho do algod o (r# 2)、Riacho Verde (r# 3)、Cachoeira (r# 4)、Chagas Manu (r# 5)、Quandu (r# 6)和balanas (r# 7)水库进行了调查。r# 1水库(流域最下游的水库)和r# 7水库(流域最上游的水库)的总磷(PT)浓度较高，pH值较低，可能对水柱中磷浓度产生较大影响。r# 3和r# 4水库以残余磷(PRe)为主，是磷的最低有效组分，因此具有较低的内负荷潜力。R#5、R#1和R#2水库总磷随沉积物深度的增加呈下降趋势，可能表明随着时间的推移，异源磷负荷增加。r# 6水库在A点和B点分别以PFeAl和PCa组分为主，说明同一水库沉积物的特征可能存在差异。在大多数分析样品中，流动态(PM)和铁铝结合态磷(PFeAl)分别含量最少和最多。
{"title":"Internal loading potential of phosphorus in reservoirs along a semiarid watershed","authors":"D. S. Moura, Antonia Samylla Oliveira De Almeida, Carlos J. Pestana, Laura Gomes Girão, José Capelo-Neto","doi":"10.1590/2318-0331.252020180023","DOIUrl":"https://doi.org/10.1590/2318-0331.252020180023","url":null,"abstract":"ABSTRACT Sediments are important to nutrient dynamics, especially due to phosphorus internal loading. Several studies have observed that internal loading could prevent water quality from improving in lakes, even when external phosphorus loading is significantly decreased. Therefore, there is an urgent need to assess the potential release of phosphorus contained in the sediment, and thus, its potential to impact water quality. In this study, the vertical and horizontal distributions of distinct phosphorus forms in the bottom sediments of artificial reservoirs, located at Forquilha watershed (Ceará, Brazil), were investigated through sequential chemical fractionation. The reservoirs Lagoa Cercada (R#1), Riacho do Algodão (R#2), Riacho Verde (R#3), Cachoeira (R#4), Chagas Manu (R#5), Quandu (R#6) and Balanças (R#7) were investigated. Reservoirs R#1 (most downstream reservoir of the watershed) and R#7 (most upstream reservoir of the watershed) had higher concentrations of total phosphorus (PT) and lower pH values, potentially exerting greater influence in phosphorus concentration in the water column. Reservoirs R#3 and R#4 presented a predominance of residual phosphorus (PRe), the least available fractions of phosphorus and thus, presented a lower potential for internal loading. Reservoirs R#5, R#1 and R#2 showed a tendency of decreasing total phosphorus (PT) as the sediment depth increased, probably indicating an increase of allochthonous phosphorus loading along time. Reservoir R#6 showed the predominance of PFeAl and PCa fractions on points A and B, respectively, showing that the characteristics of the sediments may vary in the same reservoir. Mobile (PM) and iron and aluminum-bound phosphorus (PFeAl) were the least and the most abundant fractions in most of the samples analyzed, respectively.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"29 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73284675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/2318-0331.252020190067
Luana Ferreira Gomes De Paiva, S. Montenegro, M. Cataldi
ABSTRACT Despite the water crisis in 2016, 76% of the energy in Brazil was generated by hydroelectric plants, which shows that the Brazilian system is still strongly dependent on the hydrological conditions of basins. Therefore, the flow forecasts for these plants subsidize the decision making within the scope of the Electric Sector, since they allow the evaluation of the operational conditions of the hydroelectric and thermoelectric plants through the use of energy optimization models, providing gains in the operations of SIN (Sistema Interligado Nacional – the Brazilian National Interconnected System). The precipitation forecast is of fundamental importance for the elaboration of these hydroelectric flow forecasts. For energy evaluations, the DECOMP and NEWAVE models are used, with the GEVAZP model being applied to generate scenarios through an AR (p) (autoregressive) model. Accordingly, this study shows the impact of precipitation forecast on flow predictions in the climate horizon. For this, a statistical correction was made in the rain predicted by the CFS (Climate Forecast System) model, which tends to overestimate the predicted rain, with rainfall-flow models being calibrated. Tests were performed with this new modeling system and the results, in the form of scenarios, were compared with the scenarios generated by the GEVAZP model, showing the possibility of reducing the generated range by the latter, consequently causing the DECOMP model to not consider ranges with little or no probability of occurrence, which can improve the optimization of the SIN operation planning. This work also shows that the SMAP model exhibited better performance when compared to the Neural Networks model, in terms of the average flow range predicted in relation to the observed flow. There was a clear improvement in the flow predictions with the incorporation of the rain observed one month ahead in the simulations, mainly in the forecast of high flows. Finally, the climate indices had a good relationship with the flow and rain variables.
{"title":"Prediction of monthly flows for Três Marias reservoir (São Francisco river basin) using the CFS climate forecast model","authors":"Luana Ferreira Gomes De Paiva, S. Montenegro, M. Cataldi","doi":"10.1590/2318-0331.252020190067","DOIUrl":"https://doi.org/10.1590/2318-0331.252020190067","url":null,"abstract":"ABSTRACT Despite the water crisis in 2016, 76% of the energy in Brazil was generated by hydroelectric plants, which shows that the Brazilian system is still strongly dependent on the hydrological conditions of basins. Therefore, the flow forecasts for these plants subsidize the decision making within the scope of the Electric Sector, since they allow the evaluation of the operational conditions of the hydroelectric and thermoelectric plants through the use of energy optimization models, providing gains in the operations of SIN (Sistema Interligado Nacional – the Brazilian National Interconnected System). The precipitation forecast is of fundamental importance for the elaboration of these hydroelectric flow forecasts. For energy evaluations, the DECOMP and NEWAVE models are used, with the GEVAZP model being applied to generate scenarios through an AR (p) (autoregressive) model. Accordingly, this study shows the impact of precipitation forecast on flow predictions in the climate horizon. For this, a statistical correction was made in the rain predicted by the CFS (Climate Forecast System) model, which tends to overestimate the predicted rain, with rainfall-flow models being calibrated. Tests were performed with this new modeling system and the results, in the form of scenarios, were compared with the scenarios generated by the GEVAZP model, showing the possibility of reducing the generated range by the latter, consequently causing the DECOMP model to not consider ranges with little or no probability of occurrence, which can improve the optimization of the SIN operation planning. This work also shows that the SMAP model exhibited better performance when compared to the Neural Networks model, in terms of the average flow range predicted in relation to the observed flow. There was a clear improvement in the flow predictions with the incorporation of the rain observed one month ahead in the simulations, mainly in the forecast of high flows. Finally, the climate indices had a good relationship with the flow and rain variables.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"27 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84848431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-04DOI: 10.1590/2318-0331.241920180030
Carla de Abreu D’Aquino, C. C. Scharlau, Leonardo Casagrande Dalla Vecchia
ABSTRACT This work aims to focus on proposals that could stimulate the development of small scale integrated devices for the global challenge to provide electric energy from renewable alternative resources without major interventions. It presents an evaluation of a small-scale wave energy extraction system that can be installed in marine near shore structures, such as fishing piers. The system is characterized by a small oscillating-water-column (OWC) converter composed by tubes tied to the pillars of the structure. A mathematical model of the OWC device was developed. The model relies on two main components. The first uses linear wave theory to describe the water level variation inside the tube as a result of a wave passing by. The second considers the air flux converted to mechanical torque using Wells turbine equations. The simulations were carried out for different water depths and wave parameters, to evaluate the ratio between the input and output energy throughout the year. For the case study presented in this paper, the performance would be better as long as the device is placed in a position where the waves are less influenced by the bottom friction, but it still has the necessary increment of the wave height.
{"title":"Evaluation of the energy extraction of a small-scale wave energy converter","authors":"Carla de Abreu D’Aquino, C. C. Scharlau, Leonardo Casagrande Dalla Vecchia","doi":"10.1590/2318-0331.241920180030","DOIUrl":"https://doi.org/10.1590/2318-0331.241920180030","url":null,"abstract":"ABSTRACT This work aims to focus on proposals that could stimulate the development of small scale integrated devices for the global challenge to provide electric energy from renewable alternative resources without major interventions. It presents an evaluation of a small-scale wave energy extraction system that can be installed in marine near shore structures, such as fishing piers. The system is characterized by a small oscillating-water-column (OWC) converter composed by tubes tied to the pillars of the structure. A mathematical model of the OWC device was developed. The model relies on two main components. The first uses linear wave theory to describe the water level variation inside the tube as a result of a wave passing by. The second considers the air flux converted to mechanical torque using Wells turbine equations. The simulations were carried out for different water depths and wave parameters, to evaluate the ratio between the input and output energy throughout the year. For the case study presented in this paper, the performance would be better as long as the device is placed in a position where the waves are less influenced by the bottom friction, but it still has the necessary increment of the wave height.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82803851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1590/2318-0331.241920180092
M. Santos, V. Costa, W. Fernandes, R. P. D. Paes
ABSTRACT This paper focuses on time-space characterization of drought conditions in the São Francisco River catchment, on the basis of wavelet analysis of Standardized Precipitation Index (SPI) time series. In order to improve SPI estimation, the procedures for regional analysis with L-moments were employed for defining statistically homogeneous regions. The continuous wavelet transform was then utilized for extracting time-frequency information from the resulting SPI time series in a multiresolution framework and for investigating possible teleconnections of these signals with those obtained from samples of the large-scale climate indexes ENSO and PDO. The use of regional frequency analysis with L-moments resulted in improvements in the estimation of SPI time series. It was observed that by aggregating regional information more reliable estimates of low frequency rainfall amounts were obtained. The wavelet analysis of climate indexes suggests that the more extreme dry periods in the study area are observed when the cold phase of both ENSO and the PDO coincides. While not constituting a strict cause effect relationship, it was clear that the more extreme droughts are consistently observed in this situation. However, further investigation is necessary for identifying particularities in rainfall patterns that are not associated to large-scale climate anomalies.
{"title":"Time-space characterization of droughts in the São Francisco river catchment using the Standard Precipitation Index and continuous wavelet transform","authors":"M. Santos, V. Costa, W. Fernandes, R. P. D. Paes","doi":"10.1590/2318-0331.241920180092","DOIUrl":"https://doi.org/10.1590/2318-0331.241920180092","url":null,"abstract":"ABSTRACT This paper focuses on time-space characterization of drought conditions in the São Francisco River catchment, on the basis of wavelet analysis of Standardized Precipitation Index (SPI) time series. In order to improve SPI estimation, the procedures for regional analysis with L-moments were employed for defining statistically homogeneous regions. The continuous wavelet transform was then utilized for extracting time-frequency information from the resulting SPI time series in a multiresolution framework and for investigating possible teleconnections of these signals with those obtained from samples of the large-scale climate indexes ENSO and PDO. The use of regional frequency analysis with L-moments resulted in improvements in the estimation of SPI time series. It was observed that by aggregating regional information more reliable estimates of low frequency rainfall amounts were obtained. The wavelet analysis of climate indexes suggests that the more extreme dry periods in the study area are observed when the cold phase of both ENSO and the PDO coincides. While not constituting a strict cause effect relationship, it was clear that the more extreme droughts are consistently observed in this situation. However, further investigation is necessary for identifying particularities in rainfall patterns that are not associated to large-scale climate anomalies.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"135 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86828829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1590/2318-0331.241920180115
M. A. Paixão, M. Kobiyama
ABSTRACT Mountain rivers are situated in a large portion of the terrestrial surface, especially in headwaters regions, and have been used for various purposes such as recreation, sporting activities, water resources and hydroelectric power generation. However, hydrogeomorphic characteristics of mountain rivers are not fully understood. In this context, the present paper aimed to identify relevant parameters for characterizing rivers in these environments based on bibliographical review. It was identified which parameters have been used and how they have been used to characterize mountain rivers in distinct classifications. The most cited parameters were channel gradient, relation between river width and depth, entrenchment ratio, discharge, sediment transport and grain-size distribution. Also, the current situation related to researches in fluvial geomorphology in mountain rivers in Brazil was evaluated, and the strong need of field survey as basis for the best understanding of mountain fluvial dynamics and characterization was verified.
{"title":"Relevant parameters for characterizing mountain rivers: a review","authors":"M. A. Paixão, M. Kobiyama","doi":"10.1590/2318-0331.241920180115","DOIUrl":"https://doi.org/10.1590/2318-0331.241920180115","url":null,"abstract":"ABSTRACT Mountain rivers are situated in a large portion of the terrestrial surface, especially in headwaters regions, and have been used for various purposes such as recreation, sporting activities, water resources and hydroelectric power generation. However, hydrogeomorphic characteristics of mountain rivers are not fully understood. In this context, the present paper aimed to identify relevant parameters for characterizing rivers in these environments based on bibliographical review. It was identified which parameters have been used and how they have been used to characterize mountain rivers in distinct classifications. The most cited parameters were channel gradient, relation between river width and depth, entrenchment ratio, discharge, sediment transport and grain-size distribution. Also, the current situation related to researches in fluvial geomorphology in mountain rivers in Brazil was evaluated, and the strong need of field survey as basis for the best understanding of mountain fluvial dynamics and characterization was verified.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"31 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76144820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1590/2318-0331.241920180136
G. Cavazzana, G. Lastoria, S. Gabas
ABSTRACT Since groundwater and surface waters are important components of the hydrological system, determining their interaction is essential for the efficient management of water resources by predicting the consequences of interference, whether due to the growth of demand or due to climate change. However, integrated scientific studies on these water resources are scarce, including in the Guariroba’s Environmental Protection Area, responsible for supplying 31.3% of the Campo Grandem/MS’s population, representing a local water security element. Thus, this work had as objective to evaluate the interaction between surface-groundwater in an unconfined sedimentary aquifer system, based on hydrograph separation methodologies of base flow, Flow Duration Curve (FDC) analysis, Master Recession Curve (MRC) evaluation and verification of the relationship between the surface flow, piezometric levels (PL) of the wells and the monthly precipitation. The results indicates a proportional relationship between rainfall, superficial flow and PL variations; the FDC smooth slope suggests that the baseflow is sustained by the groundwater discharge, corresponding to 89% of the total flow; the low-flow index indicates that the groundwater’s storage capacity is about 80%; the Base-Flow Index (BFI) ranging from 0.804 to 0.921, indicates a stable flow regime, aquifer’s high permeability conditions, though not uniform, and low runoff.
{"title":"Surface-groundwater interaction in unconfined sedimentary aquifer system in the Brazil’s tropical wet region","authors":"G. Cavazzana, G. Lastoria, S. Gabas","doi":"10.1590/2318-0331.241920180136","DOIUrl":"https://doi.org/10.1590/2318-0331.241920180136","url":null,"abstract":"ABSTRACT Since groundwater and surface waters are important components of the hydrological system, determining their interaction is essential for the efficient management of water resources by predicting the consequences of interference, whether due to the growth of demand or due to climate change. However, integrated scientific studies on these water resources are scarce, including in the Guariroba’s Environmental Protection Area, responsible for supplying 31.3% of the Campo Grandem/MS’s population, representing a local water security element. Thus, this work had as objective to evaluate the interaction between surface-groundwater in an unconfined sedimentary aquifer system, based on hydrograph separation methodologies of base flow, Flow Duration Curve (FDC) analysis, Master Recession Curve (MRC) evaluation and verification of the relationship between the surface flow, piezometric levels (PL) of the wells and the monthly precipitation. The results indicates a proportional relationship between rainfall, superficial flow and PL variations; the FDC smooth slope suggests that the baseflow is sustained by the groundwater discharge, corresponding to 89% of the total flow; the low-flow index indicates that the groundwater’s storage capacity is about 80%; the Base-Flow Index (BFI) ranging from 0.804 to 0.921, indicates a stable flow regime, aquifer’s high permeability conditions, though not uniform, and low runoff.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"47 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79700911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1590/2318-0331.241920190023
Bruna Arcie Polli, T. Bleninger
ABSTRACT One and three-dimensional heat transport models are compared in a dendritic reservoir in Brazil. We estimate the periods of temperature stratification for both models using physical indices and temperature gradients. The three-dimensional model reproduces more accurately the water column temperature profiles, however with focus on the physical indices (Wedderburn Number and Lake Number) similar results were obtained with both models. Secondly, we investigated the effects of temperature stratification on substance mass transport using the three-dimensional model. The advective and dispersive transport for a tracer released in a river and in a side arm of the reservoir were quantified. We identified that considering the effects of temperature stratification increased the horizontal advective transport - up to a maximum of 40% increase for the tracer released in the river, and 9% for the side arm. In relation to dispersive transport there was a decrease in transport due to temperature stratification, and no pattern was discernible for the side arm tracer modeling.
{"title":"Comparison of 1D and 3D reservoir heat transport models and temperature effects on mass transport","authors":"Bruna Arcie Polli, T. Bleninger","doi":"10.1590/2318-0331.241920190023","DOIUrl":"https://doi.org/10.1590/2318-0331.241920190023","url":null,"abstract":"ABSTRACT One and three-dimensional heat transport models are compared in a dendritic reservoir in Brazil. We estimate the periods of temperature stratification for both models using physical indices and temperature gradients. The three-dimensional model reproduces more accurately the water column temperature profiles, however with focus on the physical indices (Wedderburn Number and Lake Number) similar results were obtained with both models. Secondly, we investigated the effects of temperature stratification on substance mass transport using the three-dimensional model. The advective and dispersive transport for a tracer released in a river and in a side arm of the reservoir were quantified. We identified that considering the effects of temperature stratification increased the horizontal advective transport - up to a maximum of 40% increase for the tracer released in the river, and 9% for the side arm. In relation to dispersive transport there was a decrease in transport due to temperature stratification, and no pattern was discernible for the side arm tracer modeling.","PeriodicalId":54151,"journal":{"name":"RBRH-Revista Brasileira de Recursos Hidricos","volume":"10 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79798047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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