This article presents the calculation of the current volume of the Tres Irmaos Reservoir, SP, mor... more This article presents the calculation of the current volume of the Tres Irmaos Reservoir, SP, more specifically, it quantifies the loss of volume of its compartments due to sediment deposition and compaction. Once the silting had occurred, a new level-area-volume-operational curve was determined. For this purpose we performed the bathymetric survey of the dam. The results show that there was a reduction of 14.3%, 14.5% and 14.2% in total, useful and dead volumes, respectively, totaling a sediment volume of 1909618301.3 m3 throughout the reservoir. Through the overlapping of two Digital Land Models, i.e., one prior to filling the reservoir, created by the IBGE topographic charts dated 1972, and other based on data generated by bathymetry data during the year 2008, it was possible to observe the areas where there was sediment deposition and compaction. The erosion was concentrated in the river bed and the banks and reached an excavation of approximately 12 m. The largest sediment deposits are concentrated at the beginning of the reservoir and at the inlets of tributaries to meet quotas and get to stages of around 18 m above what was found in 1972
RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciam... more RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciamento dos recursos hídricos são os reservatórios de água e, por conseguinte a sua curva cota-área-volume (CAV). Com o objetivo de gerar a curva CAV, este estudo apresenta o método IMP e a ferramenta computacional CAV-NH. O método IMP foi aplicado ao reservatório de Ibitinga-SP/Brasil, como estudo de caso, comparando-se diferentes espaçamentos entre as seções de levantamento. As análises indicam que o procedimento adotado prove uma modelagem mais condizente com o relevo do terreno de fundo, obtendo-se uma maior acurácia, possibilitando a diminuição do trabalho de coleta de dados em campo sem prejudicar o cálculo do volume do reservatório. A ferramenta computacional desenvolvida também foi capaz de aumentar a velocidade na obtenção dos resultados finais. ABSTRACT – An important element to be considered in a watershed for good management of water resources are reservoirs of water and hence t...
This work aims to compare different methods for bathymetric surveys in large reservoirs in order ... more This work aims to compare different methods for bathymetric surveys in large reservoirs in order to evaluate changes in the volume estimation. For each reservoir were applied different distances between the parallel transects to be compared. The parallel method was also compared to the transects in zigzag. Tools of geographic information systems (GIS) were used in this work to generate digital elevation models (DEM) and to calculate volumes. It was observed that the variation of the technique involves significant changes in the result. It is concluded that the method used in the bathymetric survey of reservoirs should be carefully evaluated before the start of field surveys for the construction of the curve elevation-area volume in order to having the smallest possible error.
Despite the high water offer on the planet, the scarcity is evidenced for the irregular distribut... more Despite the high water offer on the planet, the scarcity is evidenced for the irregular distribution and the high demand caused by the population growth. In order to ensure water supply offer for the different kind of uses reservoirs, that always show sedimentation processes and consequent reservation capacity loss, are constructed. All of the reservoir management and operating policies are made based on its volume that has often express for volume – elevation and area – elevation curves, which is given by the local topography. In consequence of the reservation capacity loss caused by sedimentation processes the operating policies may be done based on incorrect data. The sedimentation quantification is done by bathymetric surveys. Faced with this situation our study highlights the importance of bathymetric surveys using a case study of Nova Avanhandava’s reservoir (Sao Paulo, Brazil), which volume expressed by volume – elevation curve was determined.
ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentat... more ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentation, hydrodynamic modelling, and dam safety assessment, among others, and the method used as well as its associated error play an important role in the quality of these studies. This study assessed the accuracy of reservoir volume calculations based on different standards for the definition of the spacing between bathymetric range lines. A technique for terrain modelling and a method for determining the survey accuracy are also proposed. Materials and methods The reference reservoir volume was based on highly detailed bathymetry (10 m resolution). Seven different spacings were selected, which generated 99 separate bathymetric data sets. For each data set, the volume was calculated based on a digital terrain model according to the usual model (triangular irregular network (TIN)) and according to the insertion of mesh points (IMP) method. This was then compared with the reference volume, and the accuracy of each survey was determined. Results and discussion Utilization of a highly detailed and reliable bathymetric survey allowed for the assessment of the associated error in each of the bathymetric data sets, as well as of the spacing standards analyzed. The accuracy of the standards analyzed using TIN modeling ranged from 0.31% to 14.40% (30 and 300 m, respectively). The high errors are attributed to the limitation of the TIN in representing regions near shores, producing incorrect shallow depth readings, resulting in a lower calculated volume than the real volume. IMP modeling exhibited great improvement in performance over the standard TIN (i.e., for 300 m accuracy of 5.51% for IMP and 14.40% for standard TIN), and in none of the cases were the generated volumes greater than the reference volume. Conclusions The IMP method proved to be consistent, improving quality of the data while reducing effort in field work. The low accuracies found showed that even surveys following the widely accepted standards contain errors of a magnitude that cannot be ignored. Thus, knowing and evaluating the survey accuracy is of fundamental importance. Definition of standard spacing for reservoirs proved to be unfeasible. This must be defined on a case-to-case basis, considering the error acceptable for the purpose of the survey.
The volume of water in a given reservoir normally decreases trough the years due to sediment accu... more The volume of water in a given reservoir normally decreases trough the years due to sediment accumulation processes. Efficient assessment of this reduction in water volume can be performed by using techniques called bathymetric surveys. We conducted two different bathymetric methods to assess the conditions of the SHP Lobo´s reservoir and compare the two techniques employed. Data was collected in 2004, 2007 and 2009. In 2004, we used the “centered section” and the “cross-section” methods. In 2007 a “zigzag” technique was applied. In 2009 all methods were again used, so that we could investigate the compatibility between them. Facing the disparate results obtained, we concluded that these different bathymetric methods are incompatible, so they cannot be jointly used to asses sediment accumulation processes.
This work aims at providing a greater theoretical and practical foundation on uniform flow in ope... more This work aims at providing a greater theoretical and practical foundation on uniform flow in open channels, as well as roughness coefficient for flow, in order to supply the variation of Manning’s coefficient for future studies along and in the transversal sections of Sapucai River in simulations of gradual varied non-permanent flow using Saint-Venant Equations. Data from some rivers in the United States were used to characterize resistance in the section. Based on these data, curves were built relating depth and Manning’s coefficient in Sapucai River in the state of Minas Gerais. The longitudinal profile was also traced using field observations. These data are essential for the calibration of hydraulic models. As a result we can observe that Manning’s coefficient calculated by the proposed method approaches the values measured in the field
ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentat... more ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentation, hydrodynamic modelling, and dam safety assessment, among others, and the method used as well as its associated error play an important role in the quality of these studies. This study assessed the accuracy of reservoir volume calculations based on different standards for the definition of the spacing between bathymetric range lines. A technique for terrain modelling and a method for determining the survey accuracy are also proposed. Materials and methods The reference reservoir volume was based on highly detailed bathymetry (10 m resolution). Seven different spacings were selected, which generated 99 separate bathymetric data sets. For each data set, the volume was calculated based on a digital terrain model according to the usual model (triangular irregular network (TIN)) and according to the insertion of mesh points (IMP) method. This was then compared with the reference volume, and the accuracy of each survey was determined. Results and discussion Utilization of a highly detailed and reliable bathymetric survey allowed for the assessment of the associated error in each of the bathymetric data sets, as well as of the spacing standards analyzed. The accuracy of the standards analyzed using TIN modeling ranged from 0.31% to 14.40% (30 and 300 m, respectively). The high errors are attributed to the limitation of the TIN in representing regions near shores, producing incorrect shallow depth readings, resulting in a lower calculated volume than the real volume. IMP modeling exhibited great improvement in performance over the standard TIN (i.e., for 300 m accuracy of 5.51% for IMP and 14.40% for standard TIN), and in none of the cases were the generated volumes greater than the reference volume. Conclusions The IMP method proved to be consistent, improving quality of the data while reducing effort in field work. The low accuracies found showed that even surveys following the widely accepted standards contain errors of a magnitude that cannot be ignored. Thus, knowing and evaluating the survey accuracy is of fundamental importance. Definition of standard spacing for reservoirs proved to be unfeasible. This must be defined on a case-to-case basis, considering the error acceptable for the purpose of the survey.
The volume of water in a given reservoir normally decreases trough the years due to sediment accu... more The volume of water in a given reservoir normally decreases trough the years due to sediment accumulation processes. Efficient assessment of this reduction in water volume can be performed by using techniques called bathymetric surveys. We conducted two different bathymetric methods to assess the conditions of the SHP Lobo´s reservoir and compare the two techniques employed. Data was collected in 2004, 2007 and 2009. In 2004, we used the “centered section” and the “cross-section” methods. In 2007 a “zigzag” technique was applied. In 2009 all methods were again used, so that we could investigate the compatibility between them. Facing the disparate results obtained, we concluded that these different bathymetric methods are incompatible, so they cannot be jointly used to asses sediment accumulation processes.
RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciam... more RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciamento dos recursos hídricos são os reservatórios de água e, por conseguinte a sua curva cota-área-volume (CAV). Com o objetivo de gerar a curva CAV, este estudo apresenta o método IMP e a ferramenta computacional CAV-NH. O método IMP foi aplicado ao reservatório de Ibitinga-SP/Brasil, como estudo de caso, comparando-se diferentes espaçamentos entre as seções de levantamento. As análises indicam que o procedimento adotado prove uma modelagem mais condizente com o relevo do terreno de fundo, obtendo-se uma maior acurácia, possibilitando a diminuição do trabalho de coleta de dados em campo sem prejudicar o cálculo do volume do reservatório. A ferramenta computacional desenvolvida também foi capaz de aumentar a velocidade na obtenção dos resultados finais. ABSTRACT – An important element to be considered in a watershed for good management of water resources are reservoirs of water and hence t...
This work aims to compare different methods for bathymetric surveys in large reservoirs in order ... more This work aims to compare different methods for bathymetric surveys in large reservoirs in order to evaluate changes in the volume estimation. For each reservoir were applied different distances between the parallel transects to be compared. The parallel method was also compared to the transects in zigzag. Tools of geographic information systems (GIS) were used in this work to generate digital elevation models (DEM) and to calculate volumes. It was observed that the variation of the technique involves significant changes in the result. It is concluded that the method used in the bathymetric survey of reservoirs should be carefully evaluated before the start of field surveys for the construction of the curve elevation-area volume in order to having the smallest possible error.
This article presents the calculation of the current volume of the Tres Irmaos Reservoir, SP, mor... more This article presents the calculation of the current volume of the Tres Irmaos Reservoir, SP, more specifically, it quantifies the loss of volume of its compartments due to sediment deposition and compaction. Once the silting had occurred, a new level-area-volume-operational curve was determined. For this purpose we performed the bathymetric survey of the dam. The results show that there was a reduction of 14.3%, 14.5% and 14.2% in total, useful and dead volumes, respectively, totaling a sediment volume of 1909618301.3 m3 throughout the reservoir. Through the overlapping of two Digital Land Models, i.e., one prior to filling the reservoir, created by the IBGE topographic charts dated 1972, and other based on data generated by bathymetry data during the year 2008, it was possible to observe the areas where there was sediment deposition and compaction. The erosion was concentrated in the river bed and the banks and reached an excavation of approximately 12 m. The largest sediment deposits are concentrated at the beginning of the reservoir and at the inlets of tributaries to meet quotas and get to stages of around 18 m above what was found in 1972
RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciam... more RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciamento dos recursos hídricos são os reservatórios de água e, por conseguinte a sua curva cota-área-volume (CAV). Com o objetivo de gerar a curva CAV, este estudo apresenta o método IMP e a ferramenta computacional CAV-NH. O método IMP foi aplicado ao reservatório de Ibitinga-SP/Brasil, como estudo de caso, comparando-se diferentes espaçamentos entre as seções de levantamento. As análises indicam que o procedimento adotado prove uma modelagem mais condizente com o relevo do terreno de fundo, obtendo-se uma maior acurácia, possibilitando a diminuição do trabalho de coleta de dados em campo sem prejudicar o cálculo do volume do reservatório. A ferramenta computacional desenvolvida também foi capaz de aumentar a velocidade na obtenção dos resultados finais. ABSTRACT – An important element to be considered in a watershed for good management of water resources are reservoirs of water and hence t...
This work aims to compare different methods for bathymetric surveys in large reservoirs in order ... more This work aims to compare different methods for bathymetric surveys in large reservoirs in order to evaluate changes in the volume estimation. For each reservoir were applied different distances between the parallel transects to be compared. The parallel method was also compared to the transects in zigzag. Tools of geographic information systems (GIS) were used in this work to generate digital elevation models (DEM) and to calculate volumes. It was observed that the variation of the technique involves significant changes in the result. It is concluded that the method used in the bathymetric survey of reservoirs should be carefully evaluated before the start of field surveys for the construction of the curve elevation-area volume in order to having the smallest possible error.
Despite the high water offer on the planet, the scarcity is evidenced for the irregular distribut... more Despite the high water offer on the planet, the scarcity is evidenced for the irregular distribution and the high demand caused by the population growth. In order to ensure water supply offer for the different kind of uses reservoirs, that always show sedimentation processes and consequent reservation capacity loss, are constructed. All of the reservoir management and operating policies are made based on its volume that has often express for volume – elevation and area – elevation curves, which is given by the local topography. In consequence of the reservation capacity loss caused by sedimentation processes the operating policies may be done based on incorrect data. The sedimentation quantification is done by bathymetric surveys. Faced with this situation our study highlights the importance of bathymetric surveys using a case study of Nova Avanhandava’s reservoir (Sao Paulo, Brazil), which volume expressed by volume – elevation curve was determined.
ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentat... more ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentation, hydrodynamic modelling, and dam safety assessment, among others, and the method used as well as its associated error play an important role in the quality of these studies. This study assessed the accuracy of reservoir volume calculations based on different standards for the definition of the spacing between bathymetric range lines. A technique for terrain modelling and a method for determining the survey accuracy are also proposed. Materials and methods The reference reservoir volume was based on highly detailed bathymetry (10 m resolution). Seven different spacings were selected, which generated 99 separate bathymetric data sets. For each data set, the volume was calculated based on a digital terrain model according to the usual model (triangular irregular network (TIN)) and according to the insertion of mesh points (IMP) method. This was then compared with the reference volume, and the accuracy of each survey was determined. Results and discussion Utilization of a highly detailed and reliable bathymetric survey allowed for the assessment of the associated error in each of the bathymetric data sets, as well as of the spacing standards analyzed. The accuracy of the standards analyzed using TIN modeling ranged from 0.31% to 14.40% (30 and 300 m, respectively). The high errors are attributed to the limitation of the TIN in representing regions near shores, producing incorrect shallow depth readings, resulting in a lower calculated volume than the real volume. IMP modeling exhibited great improvement in performance over the standard TIN (i.e., for 300 m accuracy of 5.51% for IMP and 14.40% for standard TIN), and in none of the cases were the generated volumes greater than the reference volume. Conclusions The IMP method proved to be consistent, improving quality of the data while reducing effort in field work. The low accuracies found showed that even surveys following the widely accepted standards contain errors of a magnitude that cannot be ignored. Thus, knowing and evaluating the survey accuracy is of fundamental importance. Definition of standard spacing for reservoirs proved to be unfeasible. This must be defined on a case-to-case basis, considering the error acceptable for the purpose of the survey.
The volume of water in a given reservoir normally decreases trough the years due to sediment accu... more The volume of water in a given reservoir normally decreases trough the years due to sediment accumulation processes. Efficient assessment of this reduction in water volume can be performed by using techniques called bathymetric surveys. We conducted two different bathymetric methods to assess the conditions of the SHP Lobo´s reservoir and compare the two techniques employed. Data was collected in 2004, 2007 and 2009. In 2004, we used the “centered section” and the “cross-section” methods. In 2007 a “zigzag” technique was applied. In 2009 all methods were again used, so that we could investigate the compatibility between them. Facing the disparate results obtained, we concluded that these different bathymetric methods are incompatible, so they cannot be jointly used to asses sediment accumulation processes.
This work aims at providing a greater theoretical and practical foundation on uniform flow in ope... more This work aims at providing a greater theoretical and practical foundation on uniform flow in open channels, as well as roughness coefficient for flow, in order to supply the variation of Manning’s coefficient for future studies along and in the transversal sections of Sapucai River in simulations of gradual varied non-permanent flow using Saint-Venant Equations. Data from some rivers in the United States were used to characterize resistance in the section. Based on these data, curves were built relating depth and Manning’s coefficient in Sapucai River in the state of Minas Gerais. The longitudinal profile was also traced using field observations. These data are essential for the calibration of hydraulic models. As a result we can observe that Manning’s coefficient calculated by the proposed method approaches the values measured in the field
ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentat... more ABSTRACT Purpose Determination of reservoir volume has been used in the calculation of sedimentation, hydrodynamic modelling, and dam safety assessment, among others, and the method used as well as its associated error play an important role in the quality of these studies. This study assessed the accuracy of reservoir volume calculations based on different standards for the definition of the spacing between bathymetric range lines. A technique for terrain modelling and a method for determining the survey accuracy are also proposed. Materials and methods The reference reservoir volume was based on highly detailed bathymetry (10 m resolution). Seven different spacings were selected, which generated 99 separate bathymetric data sets. For each data set, the volume was calculated based on a digital terrain model according to the usual model (triangular irregular network (TIN)) and according to the insertion of mesh points (IMP) method. This was then compared with the reference volume, and the accuracy of each survey was determined. Results and discussion Utilization of a highly detailed and reliable bathymetric survey allowed for the assessment of the associated error in each of the bathymetric data sets, as well as of the spacing standards analyzed. The accuracy of the standards analyzed using TIN modeling ranged from 0.31% to 14.40% (30 and 300 m, respectively). The high errors are attributed to the limitation of the TIN in representing regions near shores, producing incorrect shallow depth readings, resulting in a lower calculated volume than the real volume. IMP modeling exhibited great improvement in performance over the standard TIN (i.e., for 300 m accuracy of 5.51% for IMP and 14.40% for standard TIN), and in none of the cases were the generated volumes greater than the reference volume. Conclusions The IMP method proved to be consistent, improving quality of the data while reducing effort in field work. The low accuracies found showed that even surveys following the widely accepted standards contain errors of a magnitude that cannot be ignored. Thus, knowing and evaluating the survey accuracy is of fundamental importance. Definition of standard spacing for reservoirs proved to be unfeasible. This must be defined on a case-to-case basis, considering the error acceptable for the purpose of the survey.
The volume of water in a given reservoir normally decreases trough the years due to sediment accu... more The volume of water in a given reservoir normally decreases trough the years due to sediment accumulation processes. Efficient assessment of this reduction in water volume can be performed by using techniques called bathymetric surveys. We conducted two different bathymetric methods to assess the conditions of the SHP Lobo´s reservoir and compare the two techniques employed. Data was collected in 2004, 2007 and 2009. In 2004, we used the “centered section” and the “cross-section” methods. In 2007 a “zigzag” technique was applied. In 2009 all methods were again used, so that we could investigate the compatibility between them. Facing the disparate results obtained, we concluded that these different bathymetric methods are incompatible, so they cannot be jointly used to asses sediment accumulation processes.
RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciam... more RESUMO – Um importante elemento a ser considerado em uma bacia hidrográfica para um bom gerenciamento dos recursos hídricos são os reservatórios de água e, por conseguinte a sua curva cota-área-volume (CAV). Com o objetivo de gerar a curva CAV, este estudo apresenta o método IMP e a ferramenta computacional CAV-NH. O método IMP foi aplicado ao reservatório de Ibitinga-SP/Brasil, como estudo de caso, comparando-se diferentes espaçamentos entre as seções de levantamento. As análises indicam que o procedimento adotado prove uma modelagem mais condizente com o relevo do terreno de fundo, obtendo-se uma maior acurácia, possibilitando a diminuição do trabalho de coleta de dados em campo sem prejudicar o cálculo do volume do reservatório. A ferramenta computacional desenvolvida também foi capaz de aumentar a velocidade na obtenção dos resultados finais. ABSTRACT – An important element to be considered in a watershed for good management of water resources are reservoirs of water and hence t...
This work aims to compare different methods for bathymetric surveys in large reservoirs in order ... more This work aims to compare different methods for bathymetric surveys in large reservoirs in order to evaluate changes in the volume estimation. For each reservoir were applied different distances between the parallel transects to be compared. The parallel method was also compared to the transects in zigzag. Tools of geographic information systems (GIS) were used in this work to generate digital elevation models (DEM) and to calculate volumes. It was observed that the variation of the technique involves significant changes in the result. It is concluded that the method used in the bathymetric survey of reservoirs should be carefully evaluated before the start of field surveys for the construction of the curve elevation-area volume in order to having the smallest possible error.
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