Many coastal areas around the world are densely populated and at risk from flooding, but utilize different strategies to deal with coastal hazard. This chapter summarizes how Dutch concepts for coastal flood risk reduction have been explored for Galveston Bay. Firstly, it is shown how risk-based screening methods can help to evaluate various alternative strategies based on metrics such as costs, risk reduction and (societal and environmental) impacts. Application of this approach for Galveston Bay that a coastal spine alternative would entail a large investment, but it would provide the greatest risk reduction by maximizing the protected area. Secondly, a preliminary design for the coastal spine (also known as the Ike Dike) has been elaborated for protection of the region against storm surges, with involvement of Dutch and international students and experts. It includes storm surge barriers at Bolivar Roads and San Luis Pass, and several alternatives for the land barrier—including a fortified dune. Important aspects for future work are discussed, such as the cost estimation, in-bay measures, and the need for integral and proactive planning.

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Manycoastal cities are struggling with a rapidly growing risk of flooding. The sizeand complexity of these cities often demand a coordinated strategy, consistingof a combination of flood risk reduction measures. A crucial part in the designprocess is the identification of effective flood risk management strategies. However,data and resources are often limited in these early stages of design, which ischaracterized by the many different options and measures that can be considered.The focus of this study is to identify the needs and challenges of this ‘floodrisk screening’ phase and develop and implement a model framework to supportdecision making in this stage. At the centre of the study is the developmentand application of such a model: the Flood Risk Reduction Evaluation andScreening, or FLORES, model. This dissertation includes two real-life casestudies which explain the structure and development of the FLORES model, aswell as two new applications in conceptual design – flood risk analysis basedon low-resolution data, and robust decision making – that are easier toimplement in flood risk management when combined with flood risk screeningmodels.The FLORESmodel has been implemented in two case studies, one in the USA and one in Mozambique.In the Houston-Galveston Bay Area, USA, the model showed the reliance of theentire region’s flood risk on the choices made at the coastal barriers.Especially the effectiveness of inland Nature-based Solutions heavily relied onthe placement and elevation of coastal structures. In Beira, Mozambique, coastalstructures are combined and compared with other measures, such as drainagesystems, retention, and early-warning systems. The use of flood risk screeningprovided insight into the effectiveness of individual measures, as well ascombinations of measures, and prioritized strategies based on predeterminedgoals. In both cities, these insights, combined with a better understanding ofthe local flood risk and how it is influenced by risk reducing measures andfuture scenarios, can be used to support decision makers in finding the mosteffective strategy going forward.@en

Coastal cities combine intensive socioeconomic activities and investments with high exposure to flood hazards. Developing effective strategies to manage flood risk in coastal cities is often a costly and complicated process. In designing strategies, engineers rely on computationally demanding flood simulation models, but they can only compare a limited number of strategies due to computational constraints. This limits the efficacy of standard flood simulation models in the crucial conceptual phase of flood risk management. This paper presents the Flood Risk Reduction Evaluation and Screening (FLORES) model, which provides useful risk information in this early conceptual phase. FLORES rapidly performs numerous simulations and compares the impact of many storms, strategies, and future scenarios. This article presents FLORES and demonstrates its merits in a case study for Beira, Mozambique. Our results demonstrate that expansion of the drainage capacity and strengthening of its coastal protection in the southwest are crucial components of any effective flood risk management strategy for Beira.

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Large, complex coastal regions often require a combination of interventions to lower the risk of flooding to an acceptable level. In practice, a limited number of strategies are considered and interdependencies between interventions are often simplified. This paper presents the Multiple Lines of Defence Optimization System (MODOS)‐model. This quick, probabilistic model simulates and evaluates the impact of many flood risk reduction strategies while accounting for interdependencies amongst measures. The simulation includes hydraulic calculations, damage calculations, and the effects of measures for various return periods. The application and potential of this model is shown with a conceptual and simplified case study, based on the Houston‐Galveston Bay area. The analyses demonstrate how the MODOS‐model identifies trade‐offs within the system and shows how flood risk, cost, and impact respond to flood management decisions. This improved understanding of the impact of design and planning choices can benefit the discussions in finding the optimal flood risk reduction strategy for coastal regions.@en

The Galveston Bay Area is a densely populated area which is highly prone to flooding. In 2008, Hurricane Ike hit with a combination of storm surge, wind and rain. This led to an estimated 25 billion dollars in damage and nearly a hundred deaths. As a response to Hurricane Ike, several institutions have explored strategies that would protect the region from coastal flooding. Because of the complex situation, discussions on the issue have not yet led to clear or definitive conclusions. Few flood risk reduction strategies have been comprehensively assessed with impact analyses and cost estimates. More measures have been proposed, but their effectiveness cannot be evaluated without a costly investigation. In these analyses, it is often concluded that no single flood risk reduction measure can solve the bay-wide problems on its own. This would mean that research is needed on how flood risk reduction measures act in combination with each other. Moreover, non-structural measures (e.g. Nature-based Solutions, policy measures like land use zones) are increasingly implemented. The design process and discussions would greatly benefit from an increased understanding of the effects of all the proposed flood risk reduction strategies in terms of aspects such as risk reduction, costs and environmental impacts. This report will show and explain the development of a risk-based optimization model, aimed especially to fill that knowledge gap. The goal is to provide more insight in the Galveston Bay Area and the effects of design choices on the flood risk management system.@en

The Houston-Galveston Bay area can not only flood by excessive rain, but also by storm surges. Since Hurricane Ike in 2008, bay-wide flood risk reduction strategies were conceived, but only a few have been modelled. Erik van Berchum used the new fast MODOS model to plot no less than 500 different strategies, to find relations between risk reduction, construction costs and environmental impact@en

loods can have a huge impact on the regions they affect. The impact of these disasters can be reduced with a flood risk management system. Flood-prone regions often require a combination of interventions to reduce the risk to an acceptable level. The amount of risk reduction provided by various interventions can be quantified using probabilistic risk analysis.@en

The Galveston Bay Area is under significant risk from hurricane induced flooding. Ever since Hurricane Ike caused billions of damage back in 2008, the option of closing off the Galveston Bay from the Gulf of Mexico was investigated. This report, commissioned by Texas A&M University in Galveston, explores the opportunities and options for the construction of a land barrier across Galveston Island and Bolivar Peninsula. @en