Flooding Damage

DOE-STD-1020-2002

E.3.2 Flooding Damage

In many ways, flood hazards differ significantly from other natural phenomena. As an

example, it is often relatively easy to eliminate flood hazards as a potential contributor to

damage at a site through strict siting requirements. Similarly, the opportunity to effectively

utilize warning systems and emergency procedures to limit damage and personnel injury is

significantly greater in the case of flooding than it is for seismic or extreme winds and tornadoes.

The damage to buildings and the threat to public health vary depending on the type of

flood hazard. In general, structural and nonstructural damage occur if a site is inundated.

Depending on the dynamic intensity of on-site flooding, severe structural damage and complete

destruction of buildings can result. In many cases, structural failure may be less of a concern

than the damaging effects of inundation on building contents and the possible transport of

hazardous or radioactive materials.

For hazardous facilities that are not hardened against possible on-site and in-building

flooding, simply inundating the site can result in a loss of function of critical components

required to maintain safety and breach of areas that contain valuable or hazardous materials.

Structural damage to buildings depends on a number of factors related to the intensity of

the flood hazard and the local hydraulics of the site. Severe structural damage and collapse can

occur as a result of a combination of hazards such as flood stage level, flow velocity, debris or

sediment transport, wave forces, and impact loads. Flood stage is quite obviously the single

most important characteristic of the hazard (flood stages below grade generally do not result in

severe damage).

In general, the consequences of flooding increases as flooding varies from submergence

to rapidly moving water loaded with debris. Submergence results in water damage to a building

and its contents, loss of operation of electrical components, and possible structural damage

resulting from hydrostatic loads. Structural failure of roof systems can occur when drains

become clogged or are inadequate, and parapet walls allow water, snow, or ice to collect. Also,

exterior walls of reinforced concrete or masonry buildings (above and below grade) can crack

and possibly fail under hydrostatic conditions.

Dynamic flood hazards can cause excessive damage to structures that are not properly

designed. Where wave action is likely, erosion of shorelines or river banks can occur.

Structures located near the shore are subject to continuous dynamic forces that can break up a

reinforced concrete structure and at the same time undermine the foundation. Buildings with

light steel frames and metal siding, wooden structures, and unreinforced masonry are susceptible

to severe damage and even collapse if they are exposed to direct dynamic forces. Reinforced

concrete buildings are less likely to suffer severe damage or collapse. Table E-3 summarizes the

damage to buildings and flood-protection devices that various flood hazards can cause.

E-10