Search

Flood prone areas are often protected against flooding by an extensive network of flood defenses. To ensure their structural integrity, these flood defenses are periodically assessed. Many levees have been functioning well for decades, and have survived several relatively high hydraulic loads within their lifetime. However, information on survived load conditions is seldom included in levee safety assessments. Observed degradation from levee inspections is also not taken into account. That way, information that is useful to improve the accuracy of estimations of the actual strength of the levee remains unexploited. This study proposes a pragmatic approach to include observations of survived loads and levee degradation in the levee safety assessment. This approach consists of three steps: (1) a prior estimation of the failure probability, based on levee characteristics, (2) a posterior estimation of the failure probability, based on observed hydraulic loads, and (3) correction of the posterior failure probability estimation, based on levee inspections. In a case study, the estimated failure probabilities using this approach were much lower than when information on levee performance was not included. This study demonstrates the value of levee performance observations and how they could be included to improve levee safety assessments., Coastal Engineering, Hydraulic Structures and Flood Risk

Flood risk reduction can be provided by interventions such as raising land or constructing flood defences. This paper introduces an approach to optimise the selection of risk reduction strategies. It expands existing economic optimization approaches for flood defences, by introducing (largely) analytical formulations to include the effects of approaches to mitigate flood consequences. The method considers the size of the protected area and associated damages, the costs and dimensioning of interventions and the likelihood of flooding. It is applied in several practical cases. Within the context of this economic model, we conclude that a system of flood defences is more economical than a landfill for larger areas. Fills are preferred for small areas and/or for low costs. A combination of strategies is preferred when the value protected by the flood defence is low compared to the value protected by the fill, or when the high value development is relatively small in size. The sensitivity of outcomes to the choice of the main input parameters is presented, as well as implications of the results and selection of strategies in developing and developed countries. Overall, this approach supports decision makers in developing effective strategies to manage and reduce flood risk., Hydraulic Structures and Flood Risk

Flood risk reduction can be provided by interventions such as raising land or constructing flood defences. This paper introduces an approach to optimise the selection of risk reduction strategies. It expands existing economic optimization approaches for flood defences, by introducing (largely) analytical formulations to include the effects of approaches to mitigate flood consequences. The method considers the size of the protected area and associated damages, the costs and dimensioning of interventions and the likelihood of flooding. It is applied in several practical cases. Within the context of this economic model, we conclude that a system of flood defences is more economical than a landfill for larger areas. Fills are preferred for small areas and/or for low costs. A combination of strategies is preferred when the value protected by the flood defence is low compared to the value protected by the fill, or when the high value development is relatively small in size. The sensitivity of outcomes to the choice of the main input parameters is presented, as well as implications of the results and selection of strategies in developing and developed countries. Overall, this approach supports decision makers in developing effective strategies to manage and reduce flood risk., Hydraulic Structures and Flood Risk

Polders in the Netherlands are protected from flooding by flood defence systems along main water bodies such as rivers, lakes or the sea. Inside polders, canal levees provide protection from smaller water bodies. Canal levees are mainly earthen levees along drainage canals that drain excess water from polders to the main water bodies. The water levels in these canals are regulated. During the last decades, probabilistic approaches have been developed to quantify the probability of failure of flood defences along the main water bodies. This paper proposes several extensions to this method to quantify the probability of failure of canal levees. These extensions include a method to account for (i) water-level regulation in canals, (ii) the effect of maintenance dredging on the geohydrological response of the canal levee and (iii) survival of loads in the past. The results of a case study demonstrate that the proposed approach is capable of quantifying the probability of failure of canal levees and is useful for exploring the relative benefit of risk mitigating measures for canal levees., Hydraulic Structures and Flood Risk

The application of risk-based approaches for the design of flood infrastructure has become increasingly common in flood management. This approach, based on risk reduction and reliability, is used to assess the performance of conventional interventions (e.g., flood defences and dams) and to support decisions regarding their implementation. However, for more innovative solutions, performance has often not been quantified by means of these metrics and, therefore, end-users are hesitant to implement them in existing flood risk reduction systems. To overcome the gap between innovators and end-users, we present a framework based on four performance indicators, to ensure the required insights in risk and reliability are provided. The four indicators: effectiveness, durability, reliability and costs, allow end-users to evaluate, select, and implement flood adaptation innovations, and provide innovators with insight into the performance of the technology and the criteria and information necessary for successful market uptake of their innovation. The practical application of the framework is demonstrated for a (hypothetical) case of a hospital complex built in an area that has subsided below the surrounding area, which is subject to tropical rain showers. The following innovations are considered: an early flood warning system, a green roof, and a temporary flood barrier., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Hydraulic Structures and Flood Risk

Flood risk reduction systems are applied worldwide to reduce flood risk and provide protection of flood prone areas. More and more, decision makers use risk-based approach for the design and implementation of interventions in these systems. This dissertation advances existing risk-based approaches for specific interventions within a flood risk reduction system. Highlights of this dissertation include i) quantifying the reliability of canal levees, ii) evaluating the effectiveness of emergency measures, iii) optimizing portfolios (of combinations) of risk reduction strategies: flood defences and/or land fills and iv) assessing the performance of innovative interventions for flood risk reduction., Hydraulic Structures and Flood Risk

Polders in the Netherlands are protected from flooding by flood defence systems along main water bodies such as rivers, lakes or the sea. Inside polders, canal levees provide protection from smaller water bodies. Canal levees are mainly earthen levees along drainage canals that drain excess water from polders to the main water bodies. The water levels in these canals are regulated. During the last decades, probabilistic approaches have been developed to quantify the probability of failure of flood defences along the main water bodies. This paper proposes several extensions to this method to quantify the probability of failure of canal levees. These extensions include a method to account for (i) water-level regulation in canals, (ii) the effect of maintenance dredging on the geohydrological response of the canal levee and (iii) survival of loads in the past. The results of a case study demonstrate that the proposed approach is capable of quantifying the probability of failure of canal levees and is useful for exploring the relative benefit of risk mitigating measures for canal levees., Hydraulic Structures and Flood Risk

The application of risk-based approaches for the design of flood infrastructure has become increasingly common in flood management. This approach, based on risk reduction and reliability, is used to assess the performance of conventional interventions (e.g., flood defences and dams) and to support decisions regarding their implementation. However, for more innovative solutions, performance has often not been quantified by means of these metrics and, therefore, end-users are hesitant to implement them in existing flood risk reduction systems. To overcome the gap between innovators and end-users, we present a framework based on four performance indicators, to ensure the required insights in risk and reliability are provided. The four indicators: effectiveness, durability, reliability and costs, allow end-users to evaluate, select, and implement flood adaptation innovations, and provide innovators with insight into the performance of the technology and the criteria and information necessary for successful market uptake of their innovation. The practical application of the framework is demonstrated for a (hypothetical) case of a hospital complex built in an area that has subsided below the surrounding area, which is subject to tropical rain showers. The following innovations are considered: an early flood warning system, a green roof, and a temporary flood barrier., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Hydraulic Structures and Flood Risk

Flood risk reduction systems are applied worldwide to reduce flood risk and provide protection of flood prone areas. More and more, decision makers use risk-based approach for the design and implementation of interventions in these systems. This dissertation advances existing risk-based approaches for specific interventions within a flood risk reduction system. Highlights of this dissertation include i) quantifying the reliability of canal levees, ii) evaluating the effectiveness of emergency measures, iii) optimizing portfolios (of combinations) of risk reduction strategies: flood defences and/or land fills and iv) assessing the performance of innovative interventions for flood risk reduction., Hydraulic Structures and Flood Risk

This report focuses on the methodological development of the testing and implementation framework (TIF) for increasing the socio-technical readiness of climate adaptation innovations and assessing their impact on different socio-economic and environmental sectors. It is designed to be read by innovators and used as a supporting document for the application of different toolboxes made available through BRIGAID. In this report, Chapter 2 provides an overview of the different components of the TIF, including an overview of the planned testing phases. Definitions for the Performance Indicators (PI) are provided in Chapter 3, which also includes a description of how the test results which are to be integrated into the Climate Innovation Window (CIW) (in WP7). Elaborated guidelines for testing are provided in Chapters 4-6. Specifically, guidelines for assessing the technical effectiveness of innovations are provided in Chapter 4; guidelines for assessing the impact of an innovation on the environment and socio-economic sectors that will feel direct consequences of climate change are provided in Chapter 5; guidelines for assessing the societal acceptance of innovations in Chapter 6., Hydraulic Structures and Flood Risk

On August 25, 2017, Hurricane Harvey made landfall near Rockport, Texas as a Category 4 hurricane with maximum sustained winds of approximately 200 km/hour. Harvey caused severe damages in coastal Texas due to extreme winds and storm surge, but will go down in history for record-setting rainfall totals and flood-related damages. Across large portions of southeast Texas, rainfall totals during the six-day period between August 25 and 31, 2017 were amongst the highest ever recorded, causing flooding at an unprecedented scale. More than 100,000 residential properties are estimated to have been affected in southeast Texas. It is likely that Harvey will rank among the costliest storms in U.S. history. In the wake of Hurricane Harvey, Delft University of Technology has initiated a Harvey Research Team to undertake a coordinated multidisciplinary investigation of the events with a focus on the greater Houston area. This ‘fact-finding’ research is based on information available from public sources during and in the first weeks after the event. Results are therefore preliminary, but aim to provide insight into lessons that can be learned for both Texas and the Netherlands. As part of the investigations, a hackathon with more than 80 participants was organized to collect and analyze available public information. Houston was especially hard hit by flooding. During the event, all 22 watersheds in the greater Houston area experienced flooding. Many of Houston’s creeks and bayous exceeded their channel capacities, reaching water levels never before recorded. Across large portions of Harris County, rainfall totals exceeded the 1000-year return period. In addition, the water from the two reservoirs protecting downtown Houston (Addicks and Barker) were opened on August 28 to prevent catastrophic damages to the dams and further flooding in upstream communities. The releases exacerbated flooding in the areas downstream of the dams and an estimated 4,000 homes in neig, Hydraulic Structures and Flood Risk, Policy Analysis, Integral Design and Management, Safety and Security Science, System Engineering, Mathematical Geodesy and Positioning

Floods are the costliest and deadliest weather-related disaster globally. With higher population density in flood prone areas, increased urban development, and projected climate impacts, the frequency and severity of flooding in Europe is predicted to rise. While permanent flood defences have been shown to be more economically effective and reliable in the long-term than temporary flood barriers, they are expensive upfront, socially and politically complex, and time-consuming to build (Lendering et al., 2015). To adapt to climate change and mitigate flooding in the short term, it will be necessary to identify and test temporary flood barriers which can be quickly deployed during a flood event to mitigate risk. Moreover, in some areas, where permanent structures may be phsyically (or socially) infeasible, temporary (or semi-permanent) flood barriers may become a permanent strategy for mitigating floods., Hydraulic Structures and Flood Risk

Currently there is no internationally accepted framework for assessing the readiness of innovations that reduce disaster risk. To fill this gap, BRIGAID is developing a standard, comprehensive Testing and Implementation Framework (TIF). The TIF is designed to provide innovators with a framework for innovation and guidelines for assessing an innovation’s technical effectiveness, its social acceptance, and its impact on key socio-economic and environmental sectors. The vision is that the TIF will become the standard framework used to assess the effectiveness of climate adaptation innovations and the European quality label for testing., Hydraulic Structures and Flood Risk

Currently there is no internationally accepted framework for assessing the readiness of innovations that reduce disaster risk. To fill this gap, BRIGAID is developing a standard, comprehensive Testing and Implementation Framework (TIF). The TIF is designed to provide innovators with a framework for innovation and guidelines for assessing an innovation’s technical effectiveness, its social acceptance, and its impact on key socio-economic and environmental sectors. The vision is that the TIF will become the standard framework used to assess the effectiveness of climate adaptation innovations and the European quality label for testing., Hydraulic Structures and Flood Risk

Floods are the costliest and deadliest weather-related disaster globally. With higher population density in flood prone areas, increased urban development, and projected climate impacts, the frequency and severity of flooding in Europe is predicted to rise. While permanent flood defences have been shown to be more economically effective and reliable in the long-term than temporary flood barriers, they are expensive upfront, socially and politically complex, and time-consuming to build (Lendering et al., 2015). To adapt to climate change and mitigate flooding in the short term, it will be necessary to identify and test temporary flood barriers which can be quickly deployed during a flood event to mitigate risk. Moreover, in some areas, where permanent structures may be phsyically (or socially) infeasible, temporary (or semi-permanent) flood barriers may become a permanent strategy for mitigating floods., Hydraulic Structures and Flood Risk

This report focuses on the methodological development of the testing and implementation framework (TIF) for increasing the socio-technical readiness of climate adaptation innovations and assessing their impact on different socio-economic and environmental sectors. It is designed to be read by innovators and used as a supporting document for the application of different toolboxes made available through BRIGAID. In this report, Chapter 2 provides an overview of the different components of the TIF, including an overview of the planned testing phases. Definitions for the Performance Indicators (PI) are provided in Chapter 3, which also includes a description of how the test results which are to be integrated into the Climate Innovation Window (CIW) (in WP7). Elaborated guidelines for testing are provided in Chapters 4-6. Specifically, guidelines for assessing the technical effectiveness of innovations are provided in Chapter 4; guidelines for assessing the impact of an innovation on the environment and socio-economic sectors that will feel direct consequences of climate change are provided in Chapter 5; guidelines for assessing the societal acceptance of innovations in Chapter 6., Hydraulic Structures and Flood Risk

On August 25, 2017, Hurricane Harvey made landfall near Rockport, Texas as a Category 4 hurricane with maximum sustained winds of approximately 200 km/hour. Harvey caused severe damages in coastal Texas due to extreme winds and storm surge, but will go down in history for record-setting rainfall totals and flood-related damages. Across large portions of southeast Texas, rainfall totals during the six-day period between August 25 and 31, 2017 were amongst the highest ever recorded, causing flooding at an unprecedented scale. More than 100,000 residential properties are estimated to have been affected in southeast Texas. It is likely that Harvey will rank among the costliest storms in U.S. history. In the wake of Hurricane Harvey, Delft University of Technology has initiated a Harvey Research Team to undertake a coordinated multidisciplinary investigation of the events with a focus on the greater Houston area. This ‘fact-finding’ research is based on information available from public sources during and in the first weeks after the event. Results are therefore preliminary, but aim to provide insight into lessons that can be learned for both Texas and the Netherlands. As part of the investigations, a hackathon with more than 80 participants was organized to collect and analyze available public information. Houston was especially hard hit by flooding. During the event, all 22 watersheds in the greater Houston area experienced flooding. Many of Houston’s creeks and bayous exceeded their channel capacities, reaching water levels never before recorded. Across large portions of Harris County, rainfall totals exceeded the 1000-year return period. In addition, the water from the two reservoirs protecting downtown Houston (Addicks and Barker) were opened on August 28 to prevent catastrophic damages to the dams and further flooding in upstream communities. The releases exacerbated flooding in the areas downstream of the dams and an estimated 4,000 homes in neig, Hydraulic Structures and Flood Risk, Policy Analysis, Integral Design & Management, Safety and Security Science, System Engineering, Mathematical Geodesy and Positioning

Polders in the Netherlands are protected from flooding by primary and regional flood defence systems. During the last decade, scientific research in flood risk focused on the development of a probabilistic approach to quantify the probability of flooding of the primary flood defence system. This paper proposed a methodology to quantify the probability of flooding of regional flood defence systems, which required several additions to the methodology used for the primary flood defence system. These additions focused on a method to account for regulation of regional water levels, the possibility of (reduced) intrusion resistance due to maintenance dredging in regional water, the probability of traffic loads and the influence of dependence between regional water levels and the phreatic surface of a regional flood defence. In addition, reliability updating is used to demonstrate the potential for updating the probability of failure of regional flood defences with performance observations. The results demonstrated that the proposed methodology can be used to determine the probability of flooding of a regional flood defence system. In doing so, the methodology contributes to improving flood risk management in these systems., Hydraulic Structures and Flood Risk

Polders in the Netherlands are protected from flooding by primary and regional flood defence systems. During the last decade, scientific research in flood risk focused on the development of a probabilistic approach to quantify the probability of flooding of the primary flood defence system. This paper proposed a methodology to quantify the probability of flooding of regional flood defence systems, which required several additions to the methodology used for the primary flood defence system. These additions focused on a method to account for regulation of regional water levels, the possibility of (reduced) intrusion resistance due to maintenance dredging in regional water, the probability of traffic loads and the influence of dependence between regional water levels and the phreatic surface of a regional flood defence. In addition, reliability updating is used to demonstrate the potential for updating the probability of failure of regional flood defences with performance observations. The results demonstrated that the proposed methodology can be used to determine the probability of flooding of a regional flood defence system. In doing so, the methodology contributes to improving flood risk management in these systems., Hydraulic Structures and Flood Risk

Historically the Netherlands have always had to deal with the threat of flooding, both from the rivers and the sea as well as from heavy rainfall. The country consists of a large amount of polders, which are low lying areas of land protected from flooding by embankments. These polders require an extensive water storage and drainage system to discharge excess water to the surrounding ‘outside water’. Through a large system of ditches water is pumped onto large storage canals which in turn drain in to the ‘outside water’: in the sea or in rivers. In Dutch these drainage canals are called ‘Boezems’. The embankments which enclose the storage canals inside the polders are called Regional Flood Defences. The objective is to determine whether or not the flood risk approach can be applied to a system of regional flood defence systems, given the existing data and ‘state of the art’ methods. The proposed methodology will provide a basis for more thorough assessment of the regional flood defences, not only based on the safety standards, but including the failure probabilities of all relevant geotechnical failure mechanisms and corresponding consequences of flooding. The project focuses on ‘Boezemkaden’, which will be addressed as regional flood defences in the remainder of this document. These flood defences typically retain lower hydraulic heads than primary flood defences. Risk assessment methodology Flood risk is assessed by the annual expected damage due to flooding, which is estimated by multiplying the probability of flooding with the consequences of flooding. The largest knowledge gaps exist in the calculation of probabilities, because several ‘state of the art’ models are available to determine the flood consequences due to breaches in a flood defence system. Probability of flooding The probability of failure of a system of flood defences is determined based on a schematization of the system, which divides it in sections with similar strength properties. Probabilistic, Hydraulic Engineering, Civil Engineering and Geosciences

Hydraulic Engineering, Civil Engineering and Geosciences

Historically the Netherlands have always had to deal with the threat of flooding, both from the rivers and the sea as well as from heavy rainfall. The country consists of a large amount of polders, which are low lying areas of land protected from flooding by embankments. These polders require an extensive water storage and drainage system to discharge excess water to the surrounding ‘outside water’. Through a large system of ditches water is pumped onto large storage canals which in turn drain in to the ‘outside water’: in the sea or in rivers. In Dutch these drainage canals are called ‘Boezems’. The embankments which enclose the storage canals inside the polders are called Regional Flood Defences. The objective is to determine whether or not the flood risk approach can be applied to a system of regional flood defence systems, given the existing data and ‘state of the art’ methods. The proposed methodology will provide a basis for more thorough assessment of the regional flood defences, not only based on the safety standards, but including the failure probabilities of all relevant geotechnical failure mechanisms and corresponding consequences of flooding. The project focuses on ‘Boezemkaden’, which will be addressed as regional flood defences in the remainder of this document. These flood defences typically retain lower hydraulic heads than primary flood defences. Risk assessment methodology Flood risk is assessed by the annual expected damage due to flooding, which is estimated by multiplying the probability of flooding with the consequences of flooding. The largest knowledge gaps exist in the calculation of probabilities, because several ‘state of the art’ models are available to determine the flood consequences due to breaches in a flood defence system. Probability of flooding The probability of failure of a system of flood defences is determined based on a schematization of the system, which divides it in sections with similar strength properties. Probabilistic, Hydraulic Engineering, Civil Engineering and Geosciences

Hydraulic Engineering, Civil Engineering and Geosciences

Floods in the summer of 2013 in Central Europe demonstrated once again that floods account for a large part of damage and loss of life caused by natural disasters. During flood threats emergency measures, such as sand bags and big bags, are often applied to strengthen the flood defences and attempt to prevent breaches. Although these measures are often used there is limited insight in the actual reliability of the measures and their effectiveness in increasing the safety of the flood defences. The objective of this research is to develop methods to analyse the reliability and effectiveness of emergency measures for flood defences. Attention will be paid to the quantification of the reliability of emergency measures through an extensive risk analysis. When including emergency measures in the reliability analysis of flood defences failure is defined as failure of both the emergency measure as well as the flood defence. To determine the failure probability of flood defences with emergency measures two assessments are made: 1) First the probability of failure of the emergency measure is determined and 2) second the effect of the emergency measures on the failure probability of the dike section. So even when emergency measures are successfully applied the dike could still fail (!). The reliability of emergency measures is determined with event and fault tree analyses. Ad 1) The probability of a correct functioning control and/or emergency measure depends on the completion of three phases: Detection – Placement – Construction. The system is modelled in an event tree: it forms a series system which functions when each event is completed on time and correctly. Ad 2) During the operational phase, when emergency measures are placed correctly, these will reduce the failure probability of the dike section. This reduction is determined with sensitivity analyses together with project VNK. For piping the effect of reducing the hydraulic head over the flood defence is calculated in, Hydraulic Engineering, Civil Engineering and Geosciences

The Houston - Galveston area is at significant risk from hurricane induced storm surges. This paper summarizes ongoing studies on flood risk reduction for the region. Firstly, based on a simplified probabilistic hurricane surge model , the return periods of surges within the bay have been estimated. This model framework can be used to assess the effectiveness of several risk reduction interventions. Sketch- and conceptual designs have been made of a storm surge barrier in the Bolivar Roads, that would be part of the Ike Dike coastal protection concept. Such a storm surge barrier would consist of two parts, an environmental section for flow requirements (consisting of caissons with vertical gates) and a navigation section of the barrier (consisting of a barge gate), which would allow unhindered passage of navigation during normal conditions. Future questions and challenges for flood risk reduction in the Bay are identified., Hydraulic Engineering, Civil Engineering and Geosciences

During flood events emergency measures are used to prevent breaches in flood defences. However, there is still limited insight in their reliability and effectiveness. The objective of this paper is to develop a method to determine the reliability and effectiveness of emergency measures for flood defences. The investigation is focused on measures that prevent breaching of a flood defence in a river system; measures to limit and/or close breaches are beyond the scope. To determine the failure probability of flood defences with emergency measures two assessments are made: 1) the reliability of implantation of emergency measures is determined and 2) the effect of the implemented emergency measures on the reliability of the flood defence. For an emergency measure to function correctly three phases need to be passed successfully: ‘Detection’, where weak spots in the flood defence are detected, ‘Placement’, where emergency measures are built on time, and 'Construction’, which is the successful functioning of the emergency measures. The reliability of ‘Detection’ and ‘Placement’ depends on human and organizational reliability and the feasibility of complete placement of the measures within the available time. The reliability of the ‘Construction’ concerns the structural performance of the emergency measure. For a case study along a part of a river in the Netherlands a failure probability of emergency measures for the piping failure mechanism is estimated to be 1/3 per event. The human / organizational reliability during ‘Detection’ and ‘Placement’ proved to be dominant. When translated to dike ring level the failure probability is reduced with about a factor 2. This is largely explained by the length effect: with increasing amounts of weak spots in a flood defence the contribution of emergency measures will decrease., Hydraulic Engineering, Civil Engineering and Geosciences

Floods in the summer of 2013 in Central Europe demonstrated once again that floods account for a large part of damage and loss of life caused by natural disasters. During flood threats emergency measures, such as sand bags and big bags, are often applied to strengthen the flood defences and attempt to prevent breaches. Although these measures are often used there is limited insight in the actual reliability of the measures and their effectiveness in increasing the safety of the flood defences. The objective of this research is to develop methods to analyse the reliability and effectiveness of emergency measures for flood defences. Attention will be paid to the quantification of the reliability of emergency measures through an extensive risk analysis. When including emergency measures in the reliability analysis of flood defences failure is defined as failure of both the emergency measure as well as the flood defence. To determine the failure probability of flood defences with emergency measures two assessments are made: 1) First the probability of failure of the emergency measure is determined and 2) second the effect of the emergency measures on the failure probability of the dike section. So even when emergency measures are successfully applied the dike could still fail (!). The reliability of emergency measures is determined with event and fault tree analyses. Ad 1) The probability of a correct functioning control and/or emergency measure depends on the completion of three phases: Detection – Placement – Construction. The system is modelled in an event tree: it forms a series system which functions when each event is completed on time and correctly. Ad 2) During the operational phase, when emergency measures are placed correctly, these will reduce the failure probability of the dike section. This reduction is determined with sensitivity analyses together with project VNK. For piping the effect of reducing the hydraulic head over the flood defence is calculated in, Hydraulic Engineering, Civil Engineering and Geosciences

The Houston - Galveston area is at significant risk from hurricane induced storm surges. This paper summarizes ongoing studies on flood risk reduction for the region. Firstly, based on a simplified probabilistic hurricane surge model , the return periods of surges within the bay have been estimated. This model framework can be used to assess the effectiveness of several risk reduction interventions. Sketch- and conceptual designs have been made of a storm surge barrier in the Bolivar Roads, that would be part of the Ike Dike coastal protection concept. Such a storm surge barrier would consist of two parts, an environmental section for flow requirements (consisting of caissons with vertical gates) and a navigation section of the barrier (consisting of a barge gate), which would allow unhindered passage of navigation during normal conditions. Future questions and challenges for flood risk reduction in the Bay are identified., Hydraulic Engineering, Civil Engineering and Geosciences

During flood events emergency measures are used to prevent breaches in flood defences. However, there is still limited insight in their reliability and effectiveness. The objective of this paper is to develop a method to determine the reliability and effectiveness of emergency measures for flood defences. The investigation is focused on measures that prevent breaching of a flood defence in a river system; measures to limit and/or close breaches are beyond the scope. To determine the failure probability of flood defences with emergency measures two assessments are made: 1) the reliability of implantation of emergency measures is determined and 2) the effect of the implemented emergency measures on the reliability of the flood defence. For an emergency measure to function correctly three phases need to be passed successfully: ‘Detection’, where weak spots in the flood defence are detected, ‘Placement’, where emergency measures are built on time, and 'Construction’, which is the successful functioning of the emergency measures. The reliability of ‘Detection’ and ‘Placement’ depends on human and organizational reliability and the feasibility of complete placement of the measures within the available time. The reliability of the ‘Construction’ concerns the structural performance of the emergency measure. For a case study along a part of a river in the Netherlands a failure probability of emergency measures for the piping failure mechanism is estimated to be 1/3 per event. The human / organizational reliability during ‘Detection’ and ‘Placement’ proved to be dominant. When translated to dike ring level the failure probability is reduced with about a factor 2. This is largely explained by the length effect: with increasing amounts of weak spots in a flood defence the contribution of emergency measures will decrease., Hydraulic Engineering, Civil Engineering and Geosciences

New ports are mostly constructed on low lying coastal areas or shallow coastal waters. The quay wall and terminal yard are raised to a level well above mean sea level to assure flood safety. The resulting ‘convention-al terminal’ requires large volumes of fill material often dredged from the sea, which is costly. The terminal yard of a ‘polder terminal’ lies below the outside water level and is surrounded by a quay wall flood defense structure. This saves large amounts of reclamation cost but introduces higher damage potential during flood-ing and thus an increased flood risk. A risk-based framework is made to determine the optimal quay wall and polder level, which is an optimization (cost benefit analysis) under two variables. Overtopping failure proves to be the dominant failure mechanism for flooding. The reclamation savings prove to be larger than the in-creased flood risk demonstrating that the polder terminal could be an attractive alternative to the conventional terminal., Hydraulic Engineering, Civil Engineering and Geosciences

The objective of this study is to provide suitable candidate solutions for a storm surge barrier in the Bolivar Roads as part of the Ike Dike system and provide recommendations for further research., Hydraulic Engineering, Civil Engineering and Geosciences

The objective of this study is to provide suitable candidate solutions for a storm surge barrier in the Bolivar Roads as part of the Ike Dike system and provide recommendations for further research., Hydraulic Engineering, Civil Engineering and Geosciences

New ports are mostly constructed on low lying coastal areas or shallow coastal waters. The quay wall and terminal yard are raised to a level well above mean sea level to assure flood safety. The resulting ‘convention-al terminal’ requires large volumes of fill material often dredged from the sea, which is costly. The terminal yard of a ‘polder terminal’ lies below the outside water level and is surrounded by a quay wall flood defense structure. This saves large amounts of reclamation cost but introduces higher damage potential during flood-ing and thus an increased flood risk. A risk-based framework is made to determine the optimal quay wall and polder level, which is an optimization (cost benefit analysis) under two variables. Overtopping failure proves to be the dominant failure mechanism for flooding. The reclamation savings prove to be larger than the in-creased flood risk demonstrating that the polder terminal could be an attractive alternative to the conventional terminal., Hydraulic Engineering, Civil Engineering and Geosciences

New container ports are mostly constructed on low lying coastal areas or in shallow coastal waters. The quay wall and terminal yard are then raised to a level well above mean sea level to insure safety against inundation. The resulting ‘conventional terminal’ requires large volumes of good quality fill material often dredged from the sea which is costly. Royal HaskoningDHV developed the concept of a container terminal with a “polder yard”. The yard would lie below the outside water level and be surrounded by a combined quay wall flood defense structure. A water drainage system is required to drain excess water from the polder. This master thesis investigates the technical and economic feasibility. Important conditions for the feasibility of a polder terminal are low conductive (impermeable) subsoil, which limit the amount of seepage water entering the polder, and high reclamation cost. The polder terminal is technically feasible; a conceptual design is made for a case study in Tuas, Singapore. The ‘polder terminal’ could save 10 to 25% of the total cost (investment and risk) due to the lower reclamation cost. The exact saving depends on the polder depth which is bounded by uplifting failure of the polder yard. The increase in cost due to the risk of inundation and water drainage system is insufficient to counteract the large savings possible. The investments, risk and total cost of both the conventional and polder terminal are shown in the graph, where the minimum total cost of the polder terminal are lower than those of the conventional terminal., Hydraulic Engineering, Civil Engineering and Geosciences

New container ports are mostly constructed on low lying coastal areas or in shallow coastal waters. The quay wall and terminal yard are then raised to a level well above mean sea level to insure safety against inundation. The resulting ‘conventional terminal’ requires large volumes of good quality fill material often dredged from the sea which is costly. Royal HaskoningDHV developed the concept of a container terminal with a “polder yard”. The yard would lie below the outside water level and be surrounded by a combined quay wall flood defense structure. A water drainage system is required to drain excess water from the polder. This master thesis investigates the technical and economic feasibility. Important conditions for the feasibility of a polder terminal are low conductive (impermeable) subsoil, which limit the amount of seepage water entering the polder, and high reclamation cost. The polder terminal is technically feasible; a conceptual design is made for a case study in Tuas, Singapore. The ‘polder terminal’ could save 10 to 25% of the total cost (investment and risk) due to the lower reclamation cost. The exact saving depends on the polder depth which is bounded by uplifting failure of the polder yard. The increase in cost due to the risk of inundation and water drainage system is insufficient to counteract the large savings possible. The investments, risk and total cost of both the conventional and polder terminal are shown in the graph, where the minimum total cost of the polder terminal are lower than those of the conventional terminal., Hydraulic Engineering, Civil Engineering and Geosciences