Building on a Floodplain: Is It Safe?
The city of Nashville, Tennessee is facing criticism for its plans to build a brand-new stadium on land near the Cumberland River. In addition to the stadium, the city is planning to redevelop the area, adding greenways, bike lanes, sidewalks and new residential units. Redevelopment would typically be something to celebrate, but many are concerned because the project is to be built on a floodplain that was the site of a devastating flood in 2010.
The planning committee has asserted that the project will “re-center the river as a vital community amenity and bolster resiliency through enhanced floodplain and stormwater management.” Nashville councilmember Bob Mendes, however, expressed doubt about the project’s safety, stating, “there’s only so much mitigation you can do if the whole thing’s underwater.”
As the debate continues, many Nashville citizens are left wondering if it is safe to build on a floodplain.
What Is a Floodplain?
A floodplain is a flat stretch of land next to a stream or river. There are two sections of a floodplain; the first is the floodway, which is the main river channel. Floodways are sometimes dry during part of the year. The second part of a floodplain is the flood fringe, which stretches from the edge of the floodway to the bluff lines of the river valley.
Historically, it has been desirable to live near floodplains because they boast a disposition to biodiversity; rivers form a natural method of transportation and irrigation. Many ancient civilizations settled on floodplains, including the Harappan civilization and Mesopotamia, which translates to “the land between two rivers.”
Floodplains have been beneficial for many early communities, but they also bring with them the risk of flooding. Some of the worst floods in recorded history have taken place on floodplains, including the devastating 1931 Yangtze River flood. Because flooded rivers naturally overflow into floodplains, these areas are prone to repeat flooding. This frequent flooding can take a toll on communities. In 1990, one floodplain town grew so tired of flooding that they picked up and moved to higher ground. After many years of flooding, the small community of English, Indiana decided to move or demolish more than 70 homes, their newspaper, bank, library and 30 other businesses.
Not every floodplain is the same, but do they carry a common risk?
What Is a 100-Year Floodplain?
The Federal Emergency Management Agency (FEMA) refers to areas with a 1 percent probability of flooding as 100-year flood. The 1 percent chance of annual flood is also called the base flood. Base Flood Elevation (BFE) is the term FEMA uses for the “elevation of surface water resulting from a flood that has a 1% chance of equaling or exceeding that level in any given year.” These designations serve as a way of identifying risk and applying regulations.
The NFIP categorizes the risk levels of areas in a 100-year flood using Special Flood Hazard Areas (SFHAs). SFHA zones include, but are not limited to:
The National Flood Insurance Program (NFIP), managed by FEMA, requires communities to enforce floodplain management regulations
to participate. Some floodplain regulations include requiring permits to develop or begin construction within an SFHA.
Is It Safe to Build on a Floodplain?
Building on a floodplain is not expressly unsafe, but it is less safe than building in an area above a BFE. That’s because the 100 year floodplain come with a 1 percent chance of flooding in any given year
and a 26 percent chance of flooding at least once in a 30-year period. The bottom line is that building in an SFHA puts properties at risk of flooding.
Despite the flood risk, building on a floodplain can be appealing for developers because homes near water are desirable and land in a floodplain tends to be more affordable than land on high ground. It provides the property owner with the ability to buy low and sell high.
Most federal and state laws allow construction in floodplains if buildings are raised above the base flood elevation. To meet these requirements, many contractors use the “fill and build” method
of filling the low-elevation land with dirt and then building on top. This practice allows homebuilders to meet construction requirements, but it can also cause problems.
The low-elevation floodplains surrounding a river serve an important purpose: they absorb excess water. When floodplains are filled or paved over, they are no longer able to absorb water, which means excess water has nowhere to go, causing floods. Additionally, “fill and build” creates pockets of land that are at higher elevations, which creates runoff that can flood lower-elevation properties.
Before building on a floodplain, prospective homeowners may also want to consider the cost of flood insurance.
Is Flood Insurance Required in Floodplains?
Available for purchase from the NFIP or through private flood insurance providers, flood insurance is required for businesses and homes
in high-risk flood zones with government-backed mortgages. The NFIP’s residential policy covers up to $250,000 for building coverage and $100,000 for contents. Homeowners who want coverage above NFIP limits can either purchase an excess flood insurance policy
that “sits on top” of their NFIP plan, or they can purchase a separate private flood insurance policy, such as EZ Flood.
The Aon Edge Excess Flood
- Coverage up to $5MM (building and contents combined) for structures with replacement cost value up to $15MM
- Coverage for all residential risks except condominiums, subject to eligibility
- Availability in all states except AK, DC and KY
Aon Edge EZ Flood®
- Streamlined quoting process:
- Only 12 underwriting questions
- No elevation certificate or photographs are required
- Coverage up to 1.25MM for building and $875K for personal property
- Accepted by over 3,000 lenders*
- Coverage for catastrophic ground collapse
- Optional Additional Living Expenses (ALE), food spoilage and swimming pool cleanup coverage
* Prospect should confirm with their lender prior to canceling an NFIP policy and/or in advance of a loan closing transaction.
** Designed for single family residential homes — no waiting period when purchased in advance of a loan closing transaction.
This article is provided for general informational purposes only and is not intended to provide individualized advice. This article is not a substitute for any FEMA publication. This document has been compiled using information available but there are no warranties, representations or guarantees of the accuracy, adequacy, completeness or fitness for purpose of the information presented.
All descriptions, summaries or highlights of coverage are for general informational purposes only and do not amend, alter or modify the actual terms or conditions of any insurance policy. Coverage is governed only by the terms and conditions of the relevant policy.
Aon Edge Insurance Agency, Inc. is a licensed producer in all states. (TX Lic# 1339727) (CA Lic# 0E67797); Insurmark is a division of Financial & Professional Risk Solutions, Inc.