An Introduction to Flood Protection: Resiliency and Approaches

An Introduction to Flood Protection: Resiliency and Approaches

October 19, 2021

As part of a series of posts related to An Introduction to Flood Protection: What Owners Need to Know to Protect Their Properties by Doug Coenen and Ray Drexler, this article examines flood resilience of a property as well as proper flood protection approaches.

Historically, flooding is one of the costliest natural disasters in the United States on an annual basis. Flood Insurance Rate Maps (FIRMs) attempt to address area-wide flood risks retroactively and may not reflect increased rainfall intensities or localized street flooding that now occur more frequently.

Proactive owners/operators should understand flood risks from both flood frequency and flood water elevation perspectives. Local flooding in the parking lot cannot be compared to the deluge from a hurricane flooding your building, but the parking lot flooding could still be disruptive. For example, regular high-intensity rain events that enter a building or garage can be disruptive as well as costly. Whether the impacts are frequent or infrequent, flooding can have significant impacts due to lost revenue and operations, costs of repairs, and loss of patronage.

This begs: When can a reasonable and proactive investment in flood protection significantly reduce flood recovery costs?

This paper examines numerous flood protection approaches and owner needs before delving into the flood protection process. Determining the flood resilience of a property can provide a good understanding of risk associated costs.

Resilience

Using the word resilience as the basis of this discussion signifies that the ability of a property to absorb flood damages can play a significant part in determining how best to approach flood mitigation. The American Institute of Architects (AIA) defines resilience as the “ability to prepare and plan for, absorb, recover from, and more successfully adapt to adverse events.” Taking that into consideration, a key question is whether or not the cost of recovery is less impactful than the cost of the investment to protect against a potential flood. The costs are not only the cost of installation, but the cost of maintenance, the cost of inconvenience of the system, and the ability to implement the system when needed.

Flood Protection

Flood protection is intended to reduce the risk for loss of life and property by lessening the impact of flood disasters, according to the Federal Emergency Management Agency (FEMA). Effective flood protection requires understanding the broad and localized watershed issues and associated risks that impact a property, and an understanding of the community wide protection systems related to the specific property.

Flood protection design requires specialized skills: a small mistake can have disastrous consequences. The design needs to be well thought out to address the various features that the design must incorporate, consider the requirements for implementation, and detail what is required to keep the system operational and maintained.

As you would expect, the best design, built perfectly, will be useless if not properly deployed, and a well deployed system that does not consider all the points of exposure can negate the investment on protection.

Proper flood protection design requires:

  • Specialized skills
  • Attention to detail
  • Consideration of implementation, operations, and maintenance
  • Easy deployment
  • Covering all points of exposure


Flood Protection Approaches

Beginning with the end in mind, the owner should be educated on the potential flood risk and the associated applicable flood protection approaches so they can make an informed decision on what is best for their asset. Once the risk is determined to warrant investment on protection, there are two major approaches to consider, wet and dry flood protection. Furthermore, dry flood protection can be broken down into active versus passive methods.

Consideration of what triggers implementation of an active system is also important. A well-documented implementation protocol that is reviewed annually can be just as important as the system itself. The use of early warning systems that are sometimes available to the community can be used as part of this process. A site-specific system can be developed at a scale that is applicable to the flood protection system in place if a community-based system is not available.

Download An Introduction to Flood Protection: What Owners Need to Know to Protect Their Properties.

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Doug Coenen, PE is a Principal and the Civil Engineering Business Development Manager in Walter P Moore’s Infrastructure Group. He can be reached at dcoenen@walterpmoore.com.

Ray Drexler, PE is a Principal and Senior Project Manager in Walter P Moore’s Diagnostics Group. He can be reached at rdrexler@walterpmoore.com.