Natural Hazards and Earth System Sciences, Sep 24, 2010
Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the asse... more Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks (the Flood Risk Directive) signifies that flood risk analysis methods are gaining ground in EC Member States and, therefore, also in the Czech Republic (CR). Procedures of flood risk analysis have been developed in the Czech Republic since the catastrophic floods of 1997 in line with European and worldwide trends and have been tested and applied in hundreds of case studies to date. Currently, the Flood Risk Directive Guideline based on past experience with flood risk analysis applications is being processed. The aim of the paper is to present flood risk analysis procedures and specially developed techniques for the assembly of flood hazard, danger and flood risk maps. Methods related to flood risk management plans are briefly mentioned as well. The following particular problems are discussed in more detail: an application and extension of the "danger matrix" approach, the definition of residual danger, the formulation of efficiency criteria and preliminary multi-criteria flood risk assessment. These issues were tested in practical applications at pilot locations in the Czech Republic. Present experience provides evidence that the flood risk analysis methods used in the Czech Republic are in harmony with the requirements of the Flood Risk Directive. The proposed and applied methods are based primarily on existing available data such as flood extent maps, cadastral maps, the Register of Census Districts and Structures and others.
The reliability analysis of a flood protection dike depends on the probability of its failure. In... more The reliability analysis of a flood protection dike depends on the probability of its failure. In this context, the surface lining covering the landside slope of the dike plays a considerable role, as it protects the dike against failure due to overtopping. A mathematical model describing the overtopping and erosion processes is proposed. The overtopping is simulated using simple surface hydraulics equations
The text comprises the method of the determination of dispersion coefficient at water courses. Th... more The text comprises the method of the determination of dispersion coefficient at water courses. The text follows the paper Dispersion Coefficient for Open Channels Profiles of Natural Shape [4], which was published in the J. Hydrol. Hydromech., 43, 1995, 1-2, 93–101. The resulting formulae (12) to (15) and values of longitudinal dispersion coefficients in that paper are deemed to be incorrect. The corrected results of the analytical solution are given in the paper together with the comparison with numerical and experimental results.
Dam incidents and failures mainly occur during extreme floods. In the Czech Republic (CR), large-... more Dam incidents and failures mainly occur during extreme floods. In the Czech Republic (CR), large-scale regional floods were record
Floods as extreme hydrological phenomena can influence many spheres of human life due to their de... more Floods as extreme hydrological phenomena can influence many spheres of human life due to their destructive effects and significant expenses on required measures taken. Variable parameters of floods and their irregular occurrence unfavourably complicate risk management. This fact leads to complications in the systematic accomplishment of flood control measures. Flood control measures never provide absolute protection, and certain risk has to be always considered in flood-prone areas. However, negative flood effects may be reduced by implementing relevant flood control measures in the threatened area. Since the year 2007 in Europe, the flood protection concept is harmonized with the Directive 2007/60/EC of the European Parliament and the Council on the assessment and management of flood risks (https://www.eea.europa.eu/policy-documents/directive-2007-60-ec-of). During the past decade, the Czech Republic has prepared flood management tools which have been verified on hundreds of case studies. Currently, the Directive has been completely implemented, and flood management program is part of river basin plans. In this chapter, the main flood protection and flood risk-related issues are discussed. Firstly, the historical background is mentioned and discussed. Special attention is paid to the process of flood risk methodology and its applications at practical flood protection solutions. The present state of flood protection in the Czech Republic is briefly mentioned too.
Natural Hazards and Earth System Sciences, Jul 3, 2014
In this paper a model for the estimation of the number of potential fatalities is proposed based ... more In this paper a model for the estimation of the number of potential fatalities is proposed based on data from 19 past floods in central Europe. First, the factors contributing to human losses during river floods are listed and assigned to the main risk factors: hazard -exposure -vulnerability. The order of significance of individual factors has been compiled by pairwise comparison based on experience with real flood events. A comparison with factors used in existing models for the estimation of fatalities during floods shows good agreement with the significant factors identified in this study. The most significant factors affecting the number of human losses in floods have been aggregated into three groups and subjected to correlation analysis. A close-fitting regression dependence is proposed for the estimation of loss of life and calibrated using data from selected real floods in central Europe. The application of the proposed model for the estimation of fatalities due to river floods is shown via a flood risk assessment for the locality of Krnov in the Czech Republic.
Groundwater is an inseparable component of the hydrological cycle and water resource systems. It ... more Groundwater is an inseparable component of the hydrological cycle and water resource systems. It is the only source of water for the rivers during droughts and is crucial in retaining sustainable environmental and water conditions. It also plays a significant role in water supply for drinking, industrial and agricultural purposes. On the other side, groundwater effects have to be taken into account when designing and operating water structures, namely those damming water. The subsurface parts of civil and hydraulic structures may represent significant interventions into the groundwater regime if not treated. Uncontrolled seepage progressing in embankment structures and their sub-base may result in the internal erosion and internal instabilities into soils. The contemporary tool for solving groundwater-related issues is computer modelling techniques. In this chapter, the main groundwater-related issues and possibilities of their modelling are discussed. Special attention is paid to the water supply problems and groundwater protection, to the groundwater issues in urban areas during no flood periods and at the flood events. The assessment of groundwater impact on the hydraulic and civil structures is mentioned too. Numerous examples of groundwater flow modelling and its results are presented as well.
Contrary to traditional practice when rainwater is collected and conveyed from urban areas by com... more Contrary to traditional practice when rainwater is collected and conveyed from urban areas by combined, or storm sewers, present approach to the integrated stormwater control consists in the accumulation and infiltration of rainwater at the place of its origin. For design of the rainwater infiltration facility, the geological survey must be carried out, the method of infiltration has to be proposed and hydraulic calculation should be carried out. The design is subject to numerous uncertainties, arising from different conditions the infiltration tests, in design parameters and in operating an infiltration facility. In this chapter, the review of the most used facilities for infiltration is presented together with a brief description of geotechnical investigation and hydraulic approach recommended in the Czech Republic. An analysis of factors influencing the process of infiltration is carried out, related uncertainties influencing the design of the storage volume of the infiltration facility are discussed.
To quantify the effect of a current on the height of a wave's runup and overtopping combined with... more To quantify the effect of a current on the height of a wave's runup and overtopping combined with an oblique wave approach, the "FlowDike" hydraulic research project was carried out. Tests were performed on two dike slopes of 1:3 and 1:6. Waves were generated across (perpendicular to) the physical model and also inclined in-plane to the stream axis. Oblique waves were generated both towards and along the flow's direction. The effect of the current and of the wave direction on the height of the wave run-up and amount of the wave overtopping was expressed by means of a combined correction factor for the wave's inclination and flow velocity. The results of the research confirmed that the flow velocity had only a small effect.
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, Nov 1, 2016
For a design of the volume of the rainfall infiltration facility, the coefficient of infiltration... more For a design of the volume of the rainfall infiltration facility, the coefficient of infiltration is determined by an infiltration test. The use of the coefficient of infiltration brings certain uncertainties into the solution, arising from different conditions in carrying out the infiltration test and in operating a real infiltration facility. In this study an analysis is carried out of factors that influence the process of infiltration and related uncertainties influencing the determination of the storage volume of the infiltration facility. The effect of the individual factors on the design of the infiltration facility was analyzed using numerical simulations by the software HYDRUS-2D and expressed using partial reliability factors. For their determination the nomographs were set up by extensive numerical computations.
One of the basic questions related to the safety of dikes and river levees is the size of the fre... more One of the basic questions related to the safety of dikes and river levees is the size of the freeboard. One of the important parameters for freeboard design is the height of waves and wave run-up on levee slopes. Routine and standardised calculations of wave run-up deal with the freeboards of dams where wind waves originate on the still water of the reservoir. In the case of running water in streams (thereinafter only "currents") the effect of wave and current interaction on wave run-up is usually not taken into account due to the lack of reliable knowledge regarding the phenomenon. In the Czech Republic this question is topical in the case of large rivers such as the Elbe, the Vltava and the Morava. Within the framework of the projects Hydralab III and NAZV QI 92A139, hydraulic research and further analysis focused on wave run-up as a result of the combination of current and wind wave parameters were performed. The laboratory research was carried out in a hydraulic flume with a wavemaker on the right bank and a levee with a slope of 1:3 installed on the left bank opposite the wavemaker. Waves were generated both perpendicular and oblique to the levee axis; the angle of oblique wave attack varied within the range of ± 30°. The aim of this paper is to compare the results of the mentioned research with recommendations mentioned in the Czech National Standard CSN 75 0255 Calculation of wave effects on water structures and to quantify the effect of current on the wave run-up height.
Asphalt concrete linings (ACLs) are frequently used in pumped-storage hydropower schemes with fre... more Asphalt concrete linings (ACLs) are frequently used in pumped-storage hydropower schemes with frequently oscillating reservoir water levels. ACLs can be damaged during operation, which shortens their service life. One type of damage is the formation of blisters. In this study, the bacterial diversity in damaged and undamaged portions of the ACL of an upper water reservoir was evaluated. Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) was employed for the identification of the bacterial strains. No bacteria were detected growing inside the undamaged dense layer. Low bacterial diversity (2 and 4 morphotypes) was found in the upper part that has no contact with the reservoir water and in the lowest part that is permanently under water, respectively. More complex bacterial diversity (16 morphotypes covered by 2 different genera and 4 species) was found on the mastic coating of the ACL, which was alternately under and above the water. Very complex bacterial compositions (53 morphotypes covered by at least 13 different species from 6 genera) were found in samples taken from open blisters. Bacterial genera that are known to utilize asphalt products as a source of nutrition were found in the open blisters. The results reflect the importance of bacterial diversity in blisters and their possible role in ACL degradation.
Water quality in open channels plays a significant role in water resources planning and managemen... more Water quality in open channels plays a significant role in water resources planning and management. Water quality models are important decision support tools for water pollution control, the study of the aquatic ecosystems and the assessment of the effects of point and non-point (diffuse pollution) sources. Modelling of stream water quality is broadly used to assess current conditions and impacts of proposed measures in water quality management. The modelling is based on knowledge about parameters describing transport processes like hydrodynamic dispersion, advection and decay rates. According to the purpose, the scale of the studied area and the detail of solution various models of different levels are used. In this chapter, practical examples of screening, overall and detailed water quality studies applying modelling techniques are presented.
Journal of Hydrology and Hydromechanics, Aug 23, 2022
Backward erosion piping is driven by seepage forces acting on the soil grains at the downstream e... more Backward erosion piping is driven by seepage forces acting on the soil grains at the downstream end of the seepage path. A new device for the laboratory testing of backward erosion progression was developed and tested. The device consists of a plexiglass prism at which the seepage path has been predefined. The prism was equipped with an inflow consisting of gravel separated from tested sand by a strainer. The hydraulic gradient along the seepage pipe was observed by a set of piezometers and pressure cells, and the seepage discharge was measured volumetrically. The transported sediment was trapped in a vertical cone located downstream from the device. The progression of the seepage path, the piezometric heads and the trapped material was observed by two synchronous cameras. 15 trial tests have been carried out to date, and from these, the interim results are presented.
Journal of Hydrology and Hydromechanics, Sep 1, 2012
One of the basic questions related to the safety of dikes and river levees is the size of the fre... more One of the basic questions related to the safety of dikes and river levees is the size of the freeboard. One of the important parameters for freeboard design is the height of waves and wave run-up on levee slopes. Routine and standardised calculations of wave run-up deal with the freeboards of dams where wind waves originate on the still water of the reservoir. In the case of running water in streams (thereinafter only "currents") the effect of wave and current interaction on wave run-up is usually not taken into account due to the lack of reliable knowledge regarding the phenomenon. In the Czech Republic this question is topical in the case of large rivers such as the Elbe, the Vltava and the Morava. Within the framework of the projects Hydralab III and NAZV QI 92A139, hydraulic research and further analysis focused on wave run-up as a result of the combination of current and wind wave parameters were performed. The laboratory research was carried out in a hydraulic flume with a wavemaker on the right bank and a levee with a slope of 1:3 installed on the left bank opposite the wavemaker. Waves were generated both perpendicular and oblique to the levee axis; the angle of oblique wave attack varied within the range of ± 30°. The aim of this paper is to compare the results of the mentioned research with recommendations mentioned in the Czech National Standard CSN 75 0255 Calculation of wave effects on water structures and to quantify the effect of current on the wave run-up height.
The modelling of solid transport in open channels requires good knowledge about parameters relate... more The modelling of solid transport in open channels requires good knowledge about parameters related to basic processes such as hydrodynamic dispersion, advection and decay rates. Such parameters are usually determined by dye tests. Numerous tracer studies have been performed on laboratory flumes and natural rivers. However, on-site sampling is often difficult, expensive and needs special apparatus. The main aim of the study was to justify simplified method based on the monitoring of the dye cloud shape in order to determine both longitudinal and transversal dispersion coefficients. In this study, four dye tests were carried out on a small local stream (the Lipkovsky) using Rhodamine WT fluorescein dye as a tracer. The tests were carried out in such a manner that both longitudinal and horizontal transversal dispersion data were obtained. For this purpose, the visually determined extent of the dye cloud was interpreted via the analytical solution of the advection-dispersion equation. T...
Internal erosion is caused by seepage body forces acting on the soil particles. One of the most d... more Internal erosion is caused by seepage body forces acting on the soil particles. One of the most dangerous modes of internal erosion at hydraulic structures is backward erosion piping, which usually initiates at the downstream end of a seepage path, e.g., at the downstream toe of the dam. The progress of backward erosion and the development of erosion pipes were tested in a newly developed laboratory device for three types of sand with grain sizes of 0/2, 0.25/2, and 0.25/1. The piezometric head along the gradually developing seepage “pipe” was observed by seventeen piezometers and seven pressure sensors. The seepage amount was measured by the volumetric method. The critical hydraulic gradient was determined and related to the soil porosity. The progression of the seepage path and relevant characteristics such as the piezometric and pressure heads and the amount of trapped sediment were observed by two synchronous cameras. Based on the analysis of the results of 42 tests, a new empir...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Natural Hazards and Earth System Sciences, Sep 24, 2010
Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the asse... more Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks (the Flood Risk Directive) signifies that flood risk analysis methods are gaining ground in EC Member States and, therefore, also in the Czech Republic (CR). Procedures of flood risk analysis have been developed in the Czech Republic since the catastrophic floods of 1997 in line with European and worldwide trends and have been tested and applied in hundreds of case studies to date. Currently, the Flood Risk Directive Guideline based on past experience with flood risk analysis applications is being processed. The aim of the paper is to present flood risk analysis procedures and specially developed techniques for the assembly of flood hazard, danger and flood risk maps. Methods related to flood risk management plans are briefly mentioned as well. The following particular problems are discussed in more detail: an application and extension of the "danger matrix" approach, the definition of residual danger, the formulation of efficiency criteria and preliminary multi-criteria flood risk assessment. These issues were tested in practical applications at pilot locations in the Czech Republic. Present experience provides evidence that the flood risk analysis methods used in the Czech Republic are in harmony with the requirements of the Flood Risk Directive. The proposed and applied methods are based primarily on existing available data such as flood extent maps, cadastral maps, the Register of Census Districts and Structures and others.
The reliability analysis of a flood protection dike depends on the probability of its failure. In... more The reliability analysis of a flood protection dike depends on the probability of its failure. In this context, the surface lining covering the landside slope of the dike plays a considerable role, as it protects the dike against failure due to overtopping. A mathematical model describing the overtopping and erosion processes is proposed. The overtopping is simulated using simple surface hydraulics equations
The text comprises the method of the determination of dispersion coefficient at water courses. Th... more The text comprises the method of the determination of dispersion coefficient at water courses. The text follows the paper Dispersion Coefficient for Open Channels Profiles of Natural Shape [4], which was published in the J. Hydrol. Hydromech., 43, 1995, 1-2, 93–101. The resulting formulae (12) to (15) and values of longitudinal dispersion coefficients in that paper are deemed to be incorrect. The corrected results of the analytical solution are given in the paper together with the comparison with numerical and experimental results.
Dam incidents and failures mainly occur during extreme floods. In the Czech Republic (CR), large-... more Dam incidents and failures mainly occur during extreme floods. In the Czech Republic (CR), large-scale regional floods were record
Floods as extreme hydrological phenomena can influence many spheres of human life due to their de... more Floods as extreme hydrological phenomena can influence many spheres of human life due to their destructive effects and significant expenses on required measures taken. Variable parameters of floods and their irregular occurrence unfavourably complicate risk management. This fact leads to complications in the systematic accomplishment of flood control measures. Flood control measures never provide absolute protection, and certain risk has to be always considered in flood-prone areas. However, negative flood effects may be reduced by implementing relevant flood control measures in the threatened area. Since the year 2007 in Europe, the flood protection concept is harmonized with the Directive 2007/60/EC of the European Parliament and the Council on the assessment and management of flood risks (https://www.eea.europa.eu/policy-documents/directive-2007-60-ec-of). During the past decade, the Czech Republic has prepared flood management tools which have been verified on hundreds of case studies. Currently, the Directive has been completely implemented, and flood management program is part of river basin plans. In this chapter, the main flood protection and flood risk-related issues are discussed. Firstly, the historical background is mentioned and discussed. Special attention is paid to the process of flood risk methodology and its applications at practical flood protection solutions. The present state of flood protection in the Czech Republic is briefly mentioned too.
Natural Hazards and Earth System Sciences, Jul 3, 2014
In this paper a model for the estimation of the number of potential fatalities is proposed based ... more In this paper a model for the estimation of the number of potential fatalities is proposed based on data from 19 past floods in central Europe. First, the factors contributing to human losses during river floods are listed and assigned to the main risk factors: hazard -exposure -vulnerability. The order of significance of individual factors has been compiled by pairwise comparison based on experience with real flood events. A comparison with factors used in existing models for the estimation of fatalities during floods shows good agreement with the significant factors identified in this study. The most significant factors affecting the number of human losses in floods have been aggregated into three groups and subjected to correlation analysis. A close-fitting regression dependence is proposed for the estimation of loss of life and calibrated using data from selected real floods in central Europe. The application of the proposed model for the estimation of fatalities due to river floods is shown via a flood risk assessment for the locality of Krnov in the Czech Republic.
Groundwater is an inseparable component of the hydrological cycle and water resource systems. It ... more Groundwater is an inseparable component of the hydrological cycle and water resource systems. It is the only source of water for the rivers during droughts and is crucial in retaining sustainable environmental and water conditions. It also plays a significant role in water supply for drinking, industrial and agricultural purposes. On the other side, groundwater effects have to be taken into account when designing and operating water structures, namely those damming water. The subsurface parts of civil and hydraulic structures may represent significant interventions into the groundwater regime if not treated. Uncontrolled seepage progressing in embankment structures and their sub-base may result in the internal erosion and internal instabilities into soils. The contemporary tool for solving groundwater-related issues is computer modelling techniques. In this chapter, the main groundwater-related issues and possibilities of their modelling are discussed. Special attention is paid to the water supply problems and groundwater protection, to the groundwater issues in urban areas during no flood periods and at the flood events. The assessment of groundwater impact on the hydraulic and civil structures is mentioned too. Numerous examples of groundwater flow modelling and its results are presented as well.
Contrary to traditional practice when rainwater is collected and conveyed from urban areas by com... more Contrary to traditional practice when rainwater is collected and conveyed from urban areas by combined, or storm sewers, present approach to the integrated stormwater control consists in the accumulation and infiltration of rainwater at the place of its origin. For design of the rainwater infiltration facility, the geological survey must be carried out, the method of infiltration has to be proposed and hydraulic calculation should be carried out. The design is subject to numerous uncertainties, arising from different conditions the infiltration tests, in design parameters and in operating an infiltration facility. In this chapter, the review of the most used facilities for infiltration is presented together with a brief description of geotechnical investigation and hydraulic approach recommended in the Czech Republic. An analysis of factors influencing the process of infiltration is carried out, related uncertainties influencing the design of the storage volume of the infiltration facility are discussed.
To quantify the effect of a current on the height of a wave's runup and overtopping combined with... more To quantify the effect of a current on the height of a wave's runup and overtopping combined with an oblique wave approach, the "FlowDike" hydraulic research project was carried out. Tests were performed on two dike slopes of 1:3 and 1:6. Waves were generated across (perpendicular to) the physical model and also inclined in-plane to the stream axis. Oblique waves were generated both towards and along the flow's direction. The effect of the current and of the wave direction on the height of the wave run-up and amount of the wave overtopping was expressed by means of a combined correction factor for the wave's inclination and flow velocity. The results of the research confirmed that the flow velocity had only a small effect.
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, Nov 1, 2016
For a design of the volume of the rainfall infiltration facility, the coefficient of infiltration... more For a design of the volume of the rainfall infiltration facility, the coefficient of infiltration is determined by an infiltration test. The use of the coefficient of infiltration brings certain uncertainties into the solution, arising from different conditions in carrying out the infiltration test and in operating a real infiltration facility. In this study an analysis is carried out of factors that influence the process of infiltration and related uncertainties influencing the determination of the storage volume of the infiltration facility. The effect of the individual factors on the design of the infiltration facility was analyzed using numerical simulations by the software HYDRUS-2D and expressed using partial reliability factors. For their determination the nomographs were set up by extensive numerical computations.
One of the basic questions related to the safety of dikes and river levees is the size of the fre... more One of the basic questions related to the safety of dikes and river levees is the size of the freeboard. One of the important parameters for freeboard design is the height of waves and wave run-up on levee slopes. Routine and standardised calculations of wave run-up deal with the freeboards of dams where wind waves originate on the still water of the reservoir. In the case of running water in streams (thereinafter only "currents") the effect of wave and current interaction on wave run-up is usually not taken into account due to the lack of reliable knowledge regarding the phenomenon. In the Czech Republic this question is topical in the case of large rivers such as the Elbe, the Vltava and the Morava. Within the framework of the projects Hydralab III and NAZV QI 92A139, hydraulic research and further analysis focused on wave run-up as a result of the combination of current and wind wave parameters were performed. The laboratory research was carried out in a hydraulic flume with a wavemaker on the right bank and a levee with a slope of 1:3 installed on the left bank opposite the wavemaker. Waves were generated both perpendicular and oblique to the levee axis; the angle of oblique wave attack varied within the range of ± 30°. The aim of this paper is to compare the results of the mentioned research with recommendations mentioned in the Czech National Standard CSN 75 0255 Calculation of wave effects on water structures and to quantify the effect of current on the wave run-up height.
Asphalt concrete linings (ACLs) are frequently used in pumped-storage hydropower schemes with fre... more Asphalt concrete linings (ACLs) are frequently used in pumped-storage hydropower schemes with frequently oscillating reservoir water levels. ACLs can be damaged during operation, which shortens their service life. One type of damage is the formation of blisters. In this study, the bacterial diversity in damaged and undamaged portions of the ACL of an upper water reservoir was evaluated. Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) was employed for the identification of the bacterial strains. No bacteria were detected growing inside the undamaged dense layer. Low bacterial diversity (2 and 4 morphotypes) was found in the upper part that has no contact with the reservoir water and in the lowest part that is permanently under water, respectively. More complex bacterial diversity (16 morphotypes covered by 2 different genera and 4 species) was found on the mastic coating of the ACL, which was alternately under and above the water. Very complex bacterial compositions (53 morphotypes covered by at least 13 different species from 6 genera) were found in samples taken from open blisters. Bacterial genera that are known to utilize asphalt products as a source of nutrition were found in the open blisters. The results reflect the importance of bacterial diversity in blisters and their possible role in ACL degradation.
Water quality in open channels plays a significant role in water resources planning and managemen... more Water quality in open channels plays a significant role in water resources planning and management. Water quality models are important decision support tools for water pollution control, the study of the aquatic ecosystems and the assessment of the effects of point and non-point (diffuse pollution) sources. Modelling of stream water quality is broadly used to assess current conditions and impacts of proposed measures in water quality management. The modelling is based on knowledge about parameters describing transport processes like hydrodynamic dispersion, advection and decay rates. According to the purpose, the scale of the studied area and the detail of solution various models of different levels are used. In this chapter, practical examples of screening, overall and detailed water quality studies applying modelling techniques are presented.
Journal of Hydrology and Hydromechanics, Aug 23, 2022
Backward erosion piping is driven by seepage forces acting on the soil grains at the downstream e... more Backward erosion piping is driven by seepage forces acting on the soil grains at the downstream end of the seepage path. A new device for the laboratory testing of backward erosion progression was developed and tested. The device consists of a plexiglass prism at which the seepage path has been predefined. The prism was equipped with an inflow consisting of gravel separated from tested sand by a strainer. The hydraulic gradient along the seepage pipe was observed by a set of piezometers and pressure cells, and the seepage discharge was measured volumetrically. The transported sediment was trapped in a vertical cone located downstream from the device. The progression of the seepage path, the piezometric heads and the trapped material was observed by two synchronous cameras. 15 trial tests have been carried out to date, and from these, the interim results are presented.
Journal of Hydrology and Hydromechanics, Sep 1, 2012
One of the basic questions related to the safety of dikes and river levees is the size of the fre... more One of the basic questions related to the safety of dikes and river levees is the size of the freeboard. One of the important parameters for freeboard design is the height of waves and wave run-up on levee slopes. Routine and standardised calculations of wave run-up deal with the freeboards of dams where wind waves originate on the still water of the reservoir. In the case of running water in streams (thereinafter only "currents") the effect of wave and current interaction on wave run-up is usually not taken into account due to the lack of reliable knowledge regarding the phenomenon. In the Czech Republic this question is topical in the case of large rivers such as the Elbe, the Vltava and the Morava. Within the framework of the projects Hydralab III and NAZV QI 92A139, hydraulic research and further analysis focused on wave run-up as a result of the combination of current and wind wave parameters were performed. The laboratory research was carried out in a hydraulic flume with a wavemaker on the right bank and a levee with a slope of 1:3 installed on the left bank opposite the wavemaker. Waves were generated both perpendicular and oblique to the levee axis; the angle of oblique wave attack varied within the range of ± 30°. The aim of this paper is to compare the results of the mentioned research with recommendations mentioned in the Czech National Standard CSN 75 0255 Calculation of wave effects on water structures and to quantify the effect of current on the wave run-up height.
The modelling of solid transport in open channels requires good knowledge about parameters relate... more The modelling of solid transport in open channels requires good knowledge about parameters related to basic processes such as hydrodynamic dispersion, advection and decay rates. Such parameters are usually determined by dye tests. Numerous tracer studies have been performed on laboratory flumes and natural rivers. However, on-site sampling is often difficult, expensive and needs special apparatus. The main aim of the study was to justify simplified method based on the monitoring of the dye cloud shape in order to determine both longitudinal and transversal dispersion coefficients. In this study, four dye tests were carried out on a small local stream (the Lipkovsky) using Rhodamine WT fluorescein dye as a tracer. The tests were carried out in such a manner that both longitudinal and horizontal transversal dispersion data were obtained. For this purpose, the visually determined extent of the dye cloud was interpreted via the analytical solution of the advection-dispersion equation. T...
Internal erosion is caused by seepage body forces acting on the soil particles. One of the most d... more Internal erosion is caused by seepage body forces acting on the soil particles. One of the most dangerous modes of internal erosion at hydraulic structures is backward erosion piping, which usually initiates at the downstream end of a seepage path, e.g., at the downstream toe of the dam. The progress of backward erosion and the development of erosion pipes were tested in a newly developed laboratory device for three types of sand with grain sizes of 0/2, 0.25/2, and 0.25/1. The piezometric head along the gradually developing seepage “pipe” was observed by seventeen piezometers and seven pressure sensors. The seepage amount was measured by the volumetric method. The critical hydraulic gradient was determined and related to the soil porosity. The progression of the seepage path and relevant characteristics such as the piezometric and pressure heads and the amount of trapped sediment were observed by two synchronous cameras. Based on the analysis of the results of 42 tests, a new empir...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
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