Dam Breach Inundation Analysis

[Page Summary]

“Safety design includes studies to ascertain areas that would be flooded during occurrence of the design flood and in the event of dam failure. The areas downstream from the project should be evaluated to determine the needs for land acquisition, flood plain management, or other methods to prevent major damage. Information should be developed and documented suitable for releasing to downstream interests regarding remaining risks of flooding” (FEMA 93 Federal Guidelines for Dam Safety, FEMA, 2004).

“The selection of an appropriate model for computing a dam breach is dependent on the type of results needed, the level of effort that can be expended, and the potential for loss of life and economic damages that can result from a dam failure.

“For dams in rural areas where the potential for loss of life is low, a tier 1 level study using simplified methods may be appropriate. For areas where a potential dam breach can result in the loss of life an intermediate tier 2 level or advanced tier 3 should be performed. The intermediate tier 2 level study may be used for areas where more detailed calculations are justified because of the potential for loss of life. Advanced tier 3 level studies may be needed to develop dam breach inundation zone mapping for urbanized areas and for unconfined floodplains” (FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Dam Failures, FEMA, 2013).