1-3 of 3 Results

  • Keywords: flood mitigation x
Clear all

Article

David Proverbs and Jessica Lamond

Flood resilient construction has become an essential component of the integrated approach to flood risk management, now widely accepted through the concepts of making space for water and living with floods. Resilient construction has been in place for centuries, but only fairly recently has it been recognized as part of this wider strategy to manage flood risk. Buildings and the wider built environment are known to play a key role in flood risk management, and when buildings are constructed on or near to flood plains there is an obvious need to protect these. Engineered flood defense systems date back centuries, with early examples seen in China and Egypt. Levees were first built in the United States some 150 years ago, and were followed by the development of flood control acts and regulations. In 1945, Gilbert Fowler White, the so-called “father of floodplain management,” published his influential thesis which criticized the reliance on engineered flood defenses and began to change these approaches. In Europe, a shortage of farmable land led to the use of land reclamation schemes and the ensuing Land Drainage acts before massive flood events in the mid-20th century led to a shift in thinking towards the engineered defense schemes such as the Thames Barrier and Dutch dyke systems. The early 21st century witnessed the emergence of the “living with water” philosophy, which has resulted in the renewed understanding of flood resilience at a property level. The scientific study of construction methods and building technologies that are robust to flooding is a fairly recent phenomenon. There are a number of underlying reasons for this, but the change in flood risk philosophy coupled with the experience of flood events and the long process of recovery is helping to drive research and investment in this area. This has led to a more sophisticated understanding of the approaches to avoiding damage at an individual property level, categorized under three strategies, namely avoidance technology, water exclusion technology, and water entry technology. As interest and policy has shifted to water entry approaches, alongside this has been the development of research into flood resilient materials and repair and reinstatement processes, the latter gaining much attention in the recognition that experience will prompt resilient responses and that the point of reinstatement provides a good opportunity to install resilient measures. State-of-the-art practices now center on avoidance strategies incorporating planning legislation in many regions to prohibit or restrict new development in flood plains. Where development pressures mean that new buildings are permitted, there is now a body of knowledge around the impact of flooding on buildings and flood resilient construction and techniques. However, due to the variety and complexity of architecture and construction styles and varying flood risk exposure, there remain many gaps in our understanding, leading to the use of trial and error and other pragmatic approaches. Some examples of avoidance strategies include the use of earthworks, floating houses, and raised construction. The concept of property level flood resilience is an emerging concept in the United Kingdom and recognizes that in some cases a hybrid approach might be favored in which the amount of water entering a property is limited, together with the likely damage that is caused. The technology and understanding is moving forward with a greater appreciation of the benefits from combining strategies and property level measures, incorporating water resistant and resilient materials. The process of resilient repair and considerate reinstatement is another emerging feature, recognizing that there will be a need to dry, clean, and repair flood-affected buildings. The importance of effective and timely drying of properties, including the need to use materials that dry rapidly and are easy to decontaminate, has become more apparent and is gaining attention. Future developments are likely to concentrate on promoting the uptake of flood resilient materials and technologies both in the construction of new and in the retrofit and adaptation of existing properties. Further development of flood resilience technology that enhances the aesthetic appeal of adapted property would support the uptake of measures. Developments that reduce cost or that offer other aesthetic or functional advantages may also reduce the barriers to uptake. A greater understanding of performance standards for resilient materials will help provide confidence in such measures and support uptake, while further research around the breathability of materials and concerns around mold and the need to avoid creating moisture issues inside properties represent some of the key areas.

Article

Marian Muste and Ton Hoitink

With a continuous global increase in flood frequency and intensity, there is an immediate need for new science-based solutions for flood mitigation, resilience, and adaptation that can be quickly deployed in any flood-prone area. An integral part of these solutions is the availability of river discharge measurements delivered in real time with high spatiotemporal density and over large-scale areas. Stream stages and the associated discharges are the most perceivable variables of the water cycle and the ones that eventually determine the levels of hazard during floods. Consequently, the availability of discharge records (a.k.a. streamflows) is paramount for flood-risk management because they provide actionable information for organizing the activities before, during, and after floods, and they supply the data for planning and designing floodplain infrastructure. Moreover, the discharge records represent the ground-truth data for developing and continuously improving the accuracy of the hydrologic models used for forecasting streamflows. Acquiring discharge data for streams is critically important not only for flood forecasting and monitoring but also for many other practical uses, such as monitoring water abstractions for supporting decisions in various socioeconomic activities (from agriculture to industry, transportation, and recreation) and for ensuring healthy ecological flows. All these activities require knowledge of past, current, and future flows in rivers and streams. Given its importance, an ability to measure the flow in channels has preoccupied water users for millennia. Starting with the simplest volumetric methods to estimate flows, the measurement of discharge has evolved through continued innovation to sophisticated methods so that today we can continuously acquire and communicate the data in real time. There is no essential difference between the instruments and methods used to acquire streamflow data during normal conditions versus during floods. The measurements during floods are, however, complex, hazardous, and of limited accuracy compared with those acquired during normal flows. The essential differences in the configuration and operation of the instruments and methods for discharge estimation stem from the type of measurements they acquire—that is, discrete and autonomous measurements (i.e., measurements that can be taken any time any place) and those acquired continuously (i.e., estimates based on indirect methods developed for fixed locations). Regardless of the measurement situation and approach, the main concern of the data providers for flooding (as well as for other areas of water resource management) is the timely delivery of accurate discharge data at flood-prone locations across river basins.

Article

Planning systems are essentially a layer of guidance or legal requirements that sit atop plans of any type at any governmental level at or below the source of that guidance. In the case of natural hazard risk reduction, they involve rules or laws dealing with plans to reduce loss of life or property from such events. In much of the world, this is either unexplored territory or the frontier of public planning; very little of what exists in this realm predates the 1980s, although one can find earlier roots of the public discussion behind such systems. That said, the evolution of such systems in 21st century has been fairly rapid, at least in those nations with the resources and technical capacity to pursue the subject. Driven largely by substantial increases in disaster losses and growing concern about worldwide impacts of climate change, research, technology, and lessons from practice have grown apace. However, that progress has been uneven and subject to inequities in resources and governmental capacity.