Structural (Engineering) Options for Mitigation

Mitigating or lowering risk to hazards is of primary importance to individuals, communities, and nations in terms of lowering costs and saving lives, especially as the number and impact of hazards continues to increase. Structural hazard mitigation techniques are physical, or “hard” measures added, incorporated, or engineered into new and existing structures in order to fundamentally strengthen and improve the capacity and integrity of structures facing natural and technological hazards.

These techniques seek to mitigate risks and vulnerability through a broad range of measures; are used across many scales, including both public and private sectors; and can be disaster specific or generalized. For example, climate change mitigation structures includes the incorporation of elements that lower a building's greenhouse gas emissions indirectly, whereas roof tie-downs can directly lower risk from hurricanes, tornadoes, or strong storms.

While mitigation efforts are moving toward nonstructural, or “soft” measures like land use controls and planning activities, sustainable structural options for mitigation, based on natural and ecological processes, are increasingly being integrated into projects across the spectrum.

Costs related to disasters are borne not only by individuals and communities, but also nations and the community of nations, especially during the response phase of disaster management. For example, estimated damages from Hurricane Ike in 2008 included $24 billion for the United States, $7.3 billion in Cuba, and $200 million in the Bahamas. The 2005 tsunami in India cost $2.2 billion and killed approximately 10,000 people; and costs associated with the 2008 earthquake in China are estimated at $73 billion, with approximately 69,000 deaths. In order to lower these costs and save lives, it becomes imperative to implement measures that mitigate the negative aspects of development in hazardous areas. This is especially true if climate change scenarios from global warming come to fruition in the coming years, as new areas of development will prove increasingly vulnerable to floods of greater magnitude and frequency.

Structural mitigation efforts involve three scales or categories: national, community specific, and individual homeowner. These categories are usually a function of economies of scale and scope. For example, rebuilding the New Orleans levee system required both national and local efforts, whereas building codes and construction practices are usually left to individual communities. Flooding, which causes the greatest amount of property damage and loss of life in the United States on a yearly basis, is illustrative of historical and current approaches to structural mitigation. Large flood protection projects (dikes, dams, levees, and floodwalls) and flood abatement projects (projects that improve the land's ability to absorb and minimize water runoff and erosion, including soil conservation, reforestation, and terracing of farmland) are usually a federal or large-scale government responsibility to plan and construct.