Zoning for Flood Risk Reduction in Five Virginia Communities

Opportunities to Improve Flood Hazard Mapping and Municipal Practice

Yang Zhang
Virginia Tech

Publication Date: 2024

Abstract

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Zoning is a ubiquitous tool used by communities in the United States to regulate land development. Floodplain zoning can be particularly useful for mitigating the impacts of floods in high-risk areas. As flood damage and losses continue to increase with time, important questions arise about current floodplain zoning practices: (a) how do communities designate their floodplain districts?; (b) what zoning measures are currently in place to reduce flood risk?; and (c) what are the standards of these measures? This study examined floodplain ordinances in five communities in Virginia using qualitative content analysis to assess their approaches to flood risk reduction. The results showed that local governments rely on the Federal Emergency Management Agency 1% flood maps to serve as the basis for floodplain district designation. Some communities, however, also use 0.02% flood zone maps and community-defined floodplains to ensure that their ordinances have higher standard measures for flood risk reduction. Findings also showed that floodplain district delineation is constrained by outdated flood maps and inconsistent floodplain boundary and flood elevation data. The zoning measures required by the ordinances largely focus on reducing development vulnerability or flood hazard, most often by setting building elevation requirements. Few measures in the ordinances focus on limiting future flood exposure. Together these findings suggest that states should play a more active role in producing and updating flood maps to improve floodplain zoning. Communities prone to flooding should seek to introduce measures for reducing long-term flood hazard exposure, especially through community-defined special floodplains. Future flood hazard maps should include granular floodplain delineations within the 1% floodplains.

Introduction

Flooding is the most frequent and costliest hazard in the United States (First Street Foundation, 20211; Qiang, 20192; Wing et al., 20183). Addressing this national challenge requires collaboration across many sectors, including with actors at the municipal level where most land use and development decisions are made (National Research Council, 20124; Schwab et al., 20075). Zoning is a ubiquitous tool used by communities across the nation to regulate land development (Bronin, 20236; Gray, 20227). By setting up location selection criteria for development, site design standards, and district-wide land use priorities, local zoning laws can be a powerful tool to reduce flood vulnerability and increase flood resilience.

Since the passage of the National Flood Insurance Program Act of 1968, more than 23,000 municipalities in all fifty U.S. states have participated in the National Flood Insurance Program (NFIP) (Federal Emergency Management Agency [FEMA], n.d.8). As participating NFIP communities, local governments agree to adopt floodplain ordinances to mitigate their flood hazard. However, flood damage and losses in the United States have maintained an upward trajectory (Coronese et al., 20199; Crowell et al., 201010; First Street Foundation, 2021; Saharia et al., 201711). This perplexing paradox raises questions about the current floodplain zoning practices. This pilot study assesses the state of floodplain zoning by studying the floodplain ordinances in five selected communities with distinct flood hazards.

Literature Review

Floodplain Zoning

Zoning regulates how land within a municipality may be used (Bronin, 2023; Gray, 2022). More than 30,000 local governments in the U.S. have local zoning laws. Typically, local zoning ordinances define various districts based on their intended dominant use and enumerate specific requirements that must be followed within each district. Municipalities can also introduce overlay districts for certain areas with special importance to stipulate additional development requirements on top of the underlying zoning ordinance.

In 1968, Congress established the National Flood Insurance Program (NFIP) through the passage of the National Flood Insurance Act12. NFIP, administered by the Federal Emergency Management Agency (FEMA), offers flood insurance to participating communities and in return requires the communities to reduce their flood risk through the adoption of land use and development standards in their local codes (FEMA, 200513; Horn & Brown, 201814). NFIP adopts 1% Annual Exceedance Probability (AEP) floods as the base flood and stipulates basic standards for 1% floodplains that participating communities must follow (Criteria for Land Management and Use, 197915). It does not differentiate floods with higher than 1% AEPs (e.g., 50%) nor does it include requirements for floodplains with lower than 1% AEP (e.g., 0.02%). To incentivize communities to enhance their floodplain standards, FEMA established the Community Rating System which offers a reduced flood insurance premium rate when local standards go above and beyond the basic NFIP standards (FEMA, 2005, 201716).

The benefits of managing hazard exposure and limiting development vulnerability in reducing flood losses have been well documented (Brody & Highfield, 201317; Butler et al., 201618; Sun & Carson, 202019; White, 193620). A wealth of research has studied specific floodplain management practices in various localities across the United States (Brody et al., 201021; Burby et al., 200022; Deyle et al., 200823; Montz, 200024). However, we still know little about floodplain zoning, despite its wide adoption. The limited literature on this topic either focuses on cost and benefit analysis of certain flood zoning policy (Hudson & Botzen, 201925), zoning for sustainability (Jepson & Haines, 201426) and resilience (Green, 201627), or a specific type of flood zoning (Averts & Wouter Botzen, 201128). A better understanding of the current floodplain zoning practices holds the key to the continuing betterment of floodplain management and, therefore, long-term flood risk reduction in this country.

Flood Risk Reduction

When natural hazards intersect with social-economic and built environment systems, disruptions to the normal societal functions occur (Burton et al., 197829; Cutter, 200530; Peek & Mileti, 200231). Disaster risk is therefore determined by natural hazards, as well as the social-economic system and the built environment. Based on this conceptualization of risk and the literature on flood hazard mitigation (Brody et al., 200932; Schwab et al., 2007; Doberstein et al., 201933), I propose the Flood Risk Reduction Framework depicted in Figure 1, which adapts concepts from the disaster impact diagram (Schroeter et al., 202134) and the risk diagram (Jacob, 201535). Here, Hazard refers to the natural process of flood hazard. Exposure refers to the built environment that is exposed to flood hazard. Vulnerability refers to the level of susceptibility that the built environment has for flood damage. Flood Risk is a function of these three elements and is represented by the overlapping area in the diagram.

Figure 1. Flood Risk Reduction Framework

Figure 1

Note. The author designed and developed this figure.

Flood Risk Reduction therefore is to pull the three circles outward and reduce their overlap. Hazard Modeling and Mapping—which identifies flood characteristics needed for designing, implementing, and evaluating any risk reduction activity— is used to guide the flood risk reduction process. This framework encompasses three groups of strategies: reducing flood hazard, limiting development exposure, and reducing development vulnerability. There are multiple measures that can be implemented to reduce flood hazard on floodplains, including measures for preserving their flood carrying capacity and natural functions, limiting encroachment and fill in by developers, and reducing surface volume into the river channels (Birkland et al., 200336; Mudashiru et al., 202137). Limiting exposure refers to measures aimed at curbing development in hazard prone areas or removing existing at-risk development out of hazardous areas. Interventions to reduce vulnerability, on the other hand, protect people in place either by modifying the flood conditions (e.g., levees, sea walls) or by fortifying the built environment (e.g., building elevation, building codes). Hazard modeling and mapping are the foundation of all these strategies because the design, implementation, and evaluation of any flood risk reduction activity requires the knowledge of flood hazard characteristics.

Research Questions

My assessment of the state of floodplain zoning is guided by three specific research questions informed by the literature:

  1. How do communities designate their floodplain districts?
  2. What zoning measures are currently in place to reduce flood vulnerability?
  3. What are the standards of these measures?

Research Design

Site Selection

Virginia is particularly well-suited for this research. The state is bordered by the Chesapeake Bay and the Atlantic Ocean to the east and the Appalachian Mountains to its west. Flooding, whether from rain events, storm surges, or high tides, is the most common and costly natural hazard in the state (Burgos et al., 201838; Sweet & Park, 201439). The five municipalities in this study were selected purposefully to represent the different geographic regions in the state as well as the different sources of its flood hazard. They include Arlington County, Fairfax County, Roanoke County, the City of Norfolk, and the City of Roanoke. The City of Norfolk and the City of Roanoke are independent cities which do not belong to any county and are the equivalent of counties.

Arlington and Fairfax counties, located in northern Virginia, experience flooding primarily due to thunderstorms, hurricanes, and frontal storms. Flooding along the Four Mile Run floodplain has caused extensive damage in Arlington County in the past. In Fairfax County, flooding along the Potomac River and its tributaries is the product of rainfall runoff and daily tides from the Chesapeake Bay. When normal high tide corresponds with a heavy precipitation, flooding problems are exacerbated in the county.

The City of Norfolk is located in southeastern Virginia on the south shore of the Chesapeake Bay west of the Atlantic Ocean. The area is formed by the confluence of the Chesapeake Bay and several tidal rivers. The city is very vulnerable to flooding due to high storm tides and nor’easters. Minor flooding, up to four to five feet flood elevation can happen several times a year. Major storm events can push significant amounts of water from the Atlantic Ocean through the Chesapeake Bay and cause widespread flooding in the city.

Roanoke County and the City of Roanoke are located in southwest Virginia. They lie on the western slopes of the Blue Ridge Mountains and the Appalachian Highlands. Low lying areas here are subject to riverine flooding along the Roanoke River and its tributaries. This is usually the result of either tropical storms, local thunderstorms, or frontal systems.

Document Collection

I collected the floodplain ordinances for the five sites using two strategies. First, I searched the municipal code library, Municode, where I was able to procure the most recent floodplain ordinances for two counties and two cities: Arlington County, the City of Norfolk, Roanoke County, and the City of Roanoke. For the fifth jurisdiction, Fairfax County, I retrieved the document from its website. Arlington County has a standalone floodplain management ordinance in its county codes. The other four jurisdictions have their floodplain ordinances as zoning overlays in their zoning codes.

Data Analysis

I used the qualitative content analysis method (Zhang & Wildemuth, 201740) to analyze the floodplain zoning documents. The goal was to identify the regulatory measures aimed at flood risk reduction in these documents. To limit the scope of the content analysis, I focused specifically on measures concerning residential development. The codebook was developed using a combination of deductive and inductive approaches to ensure validity. I developed the initial codebook based on the Flood Risk Reduction Framework. During content analysis, new sub-categories under each flood risk reduction element emerged and were subsequently added to the initial codebook.

To ensure reliability, I used the intra-coder stability approach (Krippendorff, 200441). The document analysis took place in two rounds with a four-month gap in between. In each round and for every municipality, the manual coding process involved combing through the document, locating quotes pertaining to the themes, compiling the results using a spreadsheet codebook template. In April and May 2024, I compared, contrasted, and consolidated the two coding results. I identified the discrepancies, revisited the original documents when necessary, and resolved the conflicts.

In content analysis, replication (double coders) is generally preferred over repetition (single coder) (Krippendorff, 2004). This could be a potential reliability challenge in this research. Qualitative content analysis reveals themes—in this case flood risk reduction strategies. It does not generate subjective ranking and counts based on texts (Berke et al., 201942; Lyles & Stevens, 201443). In addition, the four-month gap between the two rounds of coding was intentional. The goal was to ensure independent coding and mitigate the subjective inertia that I may have. As such, the reliability of the coding process should not be as big of a problem as it might be if this were a quantitative content analysis.

Results

Floodplain District Delineation

Floodplain district delineation is unique in that it involves both a horizontal delineation (i.e., regulatory floodplain boundary) as well as a vertical delineation (i.e., regulatory flood elevation). All municipalities in this research use FEMA’s flood insurance rate maps as the basis for the delineation of their floodplain districts. Arlington County, Fairfax County, Roanoke County, and the City of Roanoke use solely the 1% AEP to designate floodplains. The City of Norfolk uses the 1% and 0.02% AEPs to designate floodplains in its floodplain district. In addition, the city has established a Costal Resilience Overlay District for the coastal area which is subject to higher flood hazard and requires augmented measures to increase its resilience. Norfolk also has a city-wide development requirement that aims to reduce its overall flood risk.

Within the 1% floodplain, FEMA has designated flood zone types that correspond to other geographic characteristics in the area. These flood zone types include the A zone, AE zone, coastal V zone, and VE zone (FEMA, 2005). The A Zone describes areas where no flood depth and base flood elevation information are provided. AE zone refers to 1% floodplains with base flood elevation information. Similarly, coastal V zone is used to designate areas where no base flood elevation information is available whereas the Coastal VE zone designation is for areas with this information. The AE and VE zones were identified through hydrological and hydraulic studies. Such studies have not been done in areas designated as A or V zones.

All five municipalities have a mixture of different flood zones within their 1% floodplains. This means that the communities do not have consistent floodplain boundaries and flood elevation information. For the locations where flood insurance rate maps have information gaps, the developers applying to build on the floodplain are expected to obtain such information from federal, state, and other authorities such as the U.S. Army Corps of Engineers Floodplain Information Reports or the U.S. Geological Survey Flood-Prone Quadrangles. When this is not feasible, the ordinances in all five communities consider it is the responsibility of the applicant to produce the necessary information. The applicant is expected to contract technical experts to conduct a floodplain study for the area and produce floodplain boundary and flood elevation data. The technical experts must use methods that meet the current engineering standards and submit their technical report with the development permit application.

Basic Measures for Flood Risk Reduction

All five municipalities have flood risk reduction measures for residential development in the 1% floodplain that meet the NFIP minimum standards. Table 1 provides a summary of these common flood risk reduction measures. The information is organized based on the three elements of the Flood Risk Reduction Framework: Limiting Flood Exposure, Reducing Flood Hazard, and Reducing Development Vulnerability. For each element, I grouped specific flood risk reduction measures into categories based on their flood risk reduction goal.

Table 1. Measures in City and County Ordinances for Meeting National Flood Insurance Program Minimum Standards

Flood Risk Reduction Element
Flood Risk Reduction Measures in Zoning Ordinances
Limiting Flood Exposure Setback Requirement
All new construction shall be located landward of the reach of mean high tide a
Reducing Flood Hazard Water Disturbance Limitations
Maintain the flood carrying capacity within an altered or relocated portion of any watercourse

No fill, new construction, substantial improvements, or other development in the floodway unless the encroachment will not result in any increase in base flood elevation

When floodways are not designated, no fill, new construction, substantial improvements, or other development unless the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the base flood elevation more than one foot at any point within the community

No fill for structural support of buildings a
Protection of Natural Flood Reduction Structure
No man-made alteration of sand dunes a
Reducing Development Vulnerability Elevation Requirements
The lowest floor, including basement of any residential structure elevated to or above the 1% base flood level

The bottom of the lowest horizontal structural member of the lowest floor elevated to or above the 1% base flood level a
Enclosure Limitations
Not for human habitation; Can only be used for parking, building access, or storage

Include measures to automatically equalize hydrostatic flood forces on walls by allowing for the entry and exit of floodwaters

Free of obstruction with non-supporting structures intended to collapse under wind and water loads a
Utility Systems/Equipment Protection
Electrical, heating, ventilation, plumbing, air conditioning equipment, and other service equipment, including duct work, shall be designed and/or located so as to prevent water from entering or accumulating within the components during flooding

Water supply, sanitary sewage systems, on site disposal systems shall be located and constructed to minimize flood damage/ discharges from the systems into flood waters

Oil/propane tanks must be anchored against flotation, collapse and lateral movement under flood conditions. The vent pipe extends at least three feet above the top of the tank
Existing Structure Improvement Limitations
Substantial improvement must be brought into conformity with current standards

For non-substantial improvement, no new footage can be added in floodway, and any new footage in 1% floodplain must comply with current standards
Flood Specific Building Standards
New construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure during a 1% AEP flood; shall be constructed with materials and methods to resist/minimize flood damage

The pile or column foundation and structure attached thereto is anchored to resist flotation, collapse, and lateral movement due to the effects of wind and water loads in a 1% AEP flood a
Note. The information presented in this table resulted from the author’s qualitative content analysis of the floodplain ordinances of the selected municipalities. a This measure only applies to 1% coastal floodplains. All other measures apply to both 1% inland floodplains and 1% coastal floodplains.

There was only one measure used for limiting flood exposure. NFIP’s minimum standards include a setback requirement for newly constructed and buildings being substantially improved in coastal 1% floodplains. The city of Norfolk has this policy in its floodplain ordinance. This requirement, however, does not apply to inland municipalities – Arlington county, Fairfax county, Roanoke county, and the city of Roanoke. There were two categories of measures designed to reduce flood hazard:

  1. Watercourse disturbance limitations, which aim to maintain flood carrying capacity in the area and include restrictions on fill, new construction, and substantial improvement.
  2. Protection of natural flood reduction structure measures, which limits alterations that could restrict nature’s capacity to mitigate flood hazard. Only one measure, sand dunes protection, was identified under this category.

Reducing Development Vulnerability has five categories of zoning measures: elevation requirements, enclosure limitations, utility systems/equipment protection, improvement limitations, and other flood-specific building standards. The elevation requirements stipulate the minimum elevation of the lowest floor of a residential structure and its relationship to the 1% flood elevation. Its goal is to prevent flood damage to the main component of a building during a base flood. The enclosure limitations restrict the use of the fully enclosed areas of residential structures below the regulatory building elevation. The utility systems/equipment protection measures include location and construction standards intended to protect electrical, heating, ventilation, plumbing, air conditioning equipment, water supply, sewer/sanitary sewage systems, and other utility systems of a residential property. The improvement limitations for existing structures stipulate conditions for the reconstruction, repair, modification, expansion, and/or renovation of structures lawfully constructed before the enactment of the current ordinance. An improvement of more than 50% of the structure’s market value is considered a substantial improvement and will require the entire structure to be brought to the current standards. Other flood-specific building standards include measures intended to protect the buildings from experiencing damage from the force and load of floodwater.

Higher Standard Measures for Flood Risk Reduction

As Table 2 shows, the five municipalities in this study vary with regard to the measures that they have adopted to go beyond the minimum NFIP requirements In order to limit flood exposure in Fairfax County and Arlington County, for example, the zoning ordinances require a horizontal setback of 15 feet from the edge of the 1% floodplains to any new residential development. Fairfax County also requires a floodplain easement around the flood water limit for projects passing through floodplains. The county provides technical guidance for calculating the required easement in its Public Facilities Manual. The City of Norfolk stands out for its incentives to acquire coastal properties and for its measures directing growth to higher elevations, which are designated as the Upland Resilience Overlay. The latter includes allowing developers to receive “resilience quotient points” (City of Norfolk, Zoning Ordinance, 2022, Article 5. Section 1244) for the development right extinguished in the coastal high hazard area either through direct purchase or easement. The property with its development right extinguished can only be used as passive open space or conservation in perpetuity. The resilient quotient is a system that the city of Norfolk designed to promote climate resilience of its development. The city assigns points to different resilience features of a development application. A building permit is issued only if the proposed project receives certain points. When developers are awarded points for the relinquished development right for a property, they can use these points towards their projects in the Upland Resilience Overlay district for density bonus or meeting other permit requirements. The Upland Resilience Overlay district includes areas with low risk of flooding and high potential for transformative growth.

Table 2. Higher Standard Flood Risk Reduction Measures in City and County Ordinances

Flood Risk Reduction Element
Flood Risk Reduction Measures in Zoning Ordinances
Limiting Flood Exposure Setbacks and Easement
15 feet in horizontal distance setback to the edge of a floodplain (Fairfax County, Arlington County)

All floodplains that pass through a project site must have a floodplain easement. The easement must be placed around the water limits (Fairfax County)
Acquisition Incentive
For each development right extinguished in the coastal district by direct purchase or easement, resilient quotient points may be applied to the project in the upland district. Restrict the use of the property to passive open space or conservation use in perpetuity (Norfolk)
Reducing Flood Hazard Watercourse Disturbance Limitations
New construction and substantial improvement, including fill, combined with all other existing, anticipated, and planned development shall not increase the base flood elevation (Fairfax County)

Compensatory excavation will be required for fills within a floodplain (Fairfax County)
Reducing Development Vulnerability Building Elevation Requirement
One foot (Arlington County), One and half feet (Fairfax County), Two feet (City of Roanoke, Roanoke County), Three feet (Norfolk)
Utility Systems and Equipment
All electrical, heating, ventilation, plumbing and other service equipment including duct work shall be located a minimum of: One foot above the base flood elevation (City of Roanoke, Roanoke County, Arlington County), Three feet above the base flood elevation (Norfolk)

Fairfax County has higher standard measures for Reducing Flood Hazard, including more stringent limitations on watercourse disturbance caused by development. It also has a stricter requirement for base flood elevation for new construction and substantial improvement. The county also requires compensatory excavation for fills within the 1% floodplain. When there is placement of earthen material in the floodplain in order to raise the land for a project, the developer must compensate for the reduction of floodplain’s flood carrying capacity by excavating an equivalent amount of soil or materials elsewhere in the same floodplain.

In general, higher standard measures for reducing development vulnerability focus on elevation requirements for buildings and utility systems and equipment. Arlington County requires the lowest floor of the building (which includes basements) to be elevated at least one foot above the 1% flood elevation. Fairfax County requires one and half feet. Roanoke County and the City of Roanoke require two feet. The City of Norfolk requires three feet. To protect utility systems and equipment, the City of Arlington, Roanoke County, and the City of Roanoke require one-foot elevation above the base flood elevation for electrical, heating, ventilation, plumbing and other service equipment whereas the City of Norfolk requires three feet elevation.

The City of Norfolk extends its floodplain district to include areas outside the 1% floodplain delineation. As Table 3 shows, the city requires new construction and buildings undergoing substantial improvement to be elevated one and half feet above the 0.2% flood elevation (500-year flood) or the highest adjacent grade (the highest natural elevation of the ground surface immediately next to the building structure before any construction occurs)., when flood elevation data is unavailable. It also stipulates a city-wide 1.5 feet elevation requirement above the highest adjacent grade for residential buildings and utility systems and equipment.

Table 3. City of Norfolk Flood Risk Reduction Measures Outside of 1% Floodplain

Measures for Buildings in 0.2% Floodplains
City-Wide Measures
Building Elevation
New construction and substantial improvement shall have the lowest floor, including basement, elevated to one and one-half (1.5) feet above the highest grade immediately adjacent to the structure or 1.5 ft above the base flood elevation, when such data are available		 Building Elevation
The lowest habitable floor shall be elevated at least 16 inches above the highest adjacent grade

Utility and Service Equipment
All significant electrical and mechanical equipment shall be elevated at least 16 inches above the highest adjacent grade

Discussion

Floodplain District Delineation

The floodplain district delineation relies on the FEMA flood hazard maps, which for the communities in this study were produced between the early 2000s (Roanoke County) to the late 2010s (City of Norfolk). The lack of up-to-date maps could result in high flood hazard areas failing to be accurately delineated in the floodplain district maps. The lengthy map update cycle has been a long-standing critique of the FEMA flood hazard maps (Grimm, 202045; Pralle, 201846). In the early 2000s, FEMA launched its digital map modernization program to expedite the map update process. However, its level of success is constrained by funding and agency priorities (Grimm, 2020; Wing et al., 2018).

Besides the problem with map currency, local floodplain district delineation is also limited by the inconsistent availability of floodplain boundary and flood elevation data. Some FEMA floodplain maps have well defined floodplain boundaries and flood elevation levels identified (FEMA, 2005). This results in zoning measures being widely prescribed across floodplains without the floodplain boundary and flood elevation data needed to ensure those measures correspond to the flood hazard. In these situations, the burden is on the developers to conduct the engineering studies to produce the necessary information and the municipal floodplain managers to review the hydrological and hydraulic models for accuracy and compliance.

Flood studies are a technical, data-intensive process that can only be properly conducted by licensed engineers. The lack of engineers who can perform floodplain studies and the cost associated with it (Maxwell, 201647) are often daunting impediments for communities wanting to implement their floodplain ordinance. While there is no literature documenting specifically the flood engineering capacity discrepancy across different localities, data from the American Society of Civil Engineering and the American Society of Engineering Education has shown a severe shortage of civil engineers in both public and private sectors in the United States (Kodey et al., 202348; Reid, 202349). Additionally, city or county governments in less populated or lower-income communities often do not have staff engineers and have to rely on private consultants for this work. Board members of the Virginia Floodplain Management Association stated at their 2023 annual conference in Richmond, VA, that more than 30% of Virginia’s city and county governments do not have engineers on their staff (personal communication, November 14, 2023).

Flood Risk Reduction and Floodplain Zoning

Most municipalities use a myriad of plans and vision documents to guide the future direction of their development (Berke et al., 201550; Berke et al., 2019). Just as zoning regulations seek to implement a community’s desired patterns of growth, zoning is a critical approach to achieve a community’s flood risk reduction vision by regulating the relationship between development and flood hazard in the community.

This pilot study suggests that local floodplain ordinances are principally shaped by the NFIP’s minimum standards for the 1% AEP floodplains. Notably, the zoning ordinances reviewed for this investigation were largely focused on reducing development vulnerability and flood hazard, rather than on limiting exposure to flooding. This is likely due to NFIP standards which have minimal land use restrictions to prevent residential development in the floodplains through means such as site selection criteria and setbacks. As a result, the municipal zoning ordinances attempt to achieve flood risk reduction primarily by imposing elevation requirements for structure and utility equipment, building enclosure limitations, flood resistant building standards, and maintaining floodplains’ flood carrying capacity. Development in floodplains is not explicitly restricted as long as any disturbance or reduction of flood carrying capacity is compensated.

Municipalities can choose to go beyond the NFIP standards in their floodplain ordinance. The popular adoption of additional elevation requirement suggests that imposing elevation requirement while permitting development in the floodplains is a strategy that most communities can likely get behind. In contrast to the NFIP’s minimal focus on limiting flood exposure, several municipalities in this study codified additional land use restrictions in the floodplains to curb the flood exposure. Some of these measures limit development in the floodplains and others aim to prevent development altogether. For limiting flood hazard exposure, avoidance of high hazard areas is the most effective flood risk reduction strategy and is also the most contentious because it involves restricting land use rights. The examples in this study highlight the importance of community ingenuity and place-based solutions in advancing retreat from high flood hazard areas (Brody et al., 2010; Cutter et al., 200851).

Conclusions

Policy Implications

The limitations of the current FEMA maps—including the need to increase their accuracy and coverage—are well established (Grimm, 2020; Wing et al., 201752). Beyond providing evidence supporting this position, this study has also shown that flood maps will serve local floodplain management better if they consistently provide floodplain boundary and flood elevation data. This information is vital for communities to implement flood risk reduction measures effectively. For developers and property owners, it aids in ensuring compliance with development standards and elevation requirements within the floodplains.

FEMA is the leading federal agency in producing and updating flood hazard maps, but states can play a more active role in filling the gaps. For example, North Carolina—through its Cooperating Technical Partner State agreement with FEMA (202153)—assumes primary responsibility for conducting flood studies and producing updated flood hazard maps. Partnerships between FEMA and states like North Carolina could serve as a model for flood hazard mapping. By leveraging local expertise and resources, states can enhance the currency and accuracy of FEMA maps at the community scale. Expanding these partnerships to more states would enable FEMA and states to create more detailed flood hazard maps, ultimately strengthening local floodplain ordinances and leading to more effective flood risk reductions.

As stated above, the NFIP minimum requirements lead to municipal flood risk reduction measures that are primarily focused on reducing development vulnerability and flood hazard, with little concern for limiting flood exposure by preventing development in high hazard areas. As the examples in this study demonstrated, communities with high flood hazard should actively explore land use measures that will reduce their long-term flood exposure (e.g., setbacks, floodplain easement, clustering development, acquisition incentives). Adopting development restrictions in floodplains may create political backlash or legal obstacles (e.g., landowners could sue the local, state, or federal government for infringing on private property rights without just compensation).In communities with these concerns, municipal governments should start by restricting development in special floodplains that are frequently flooded or which exhibit other important environmental and ecological values.

Lastly, this study supports critiques challenging the efficacy of using 1% flood as the basis for floodplain regulations. Within 1% floodplains, there are a range of more and less vulnerable areas. Treating them the same way limits targeted use of restrictive land use measures. Land that is frequently flooded—such as extremely low-lying parcels, wetlands, or coastal marshlands—should be prioritized for flood risk reduction and for maintaining floodplain functions. Flood hazard maps that depict granular floodplains will enable communities to adopt targeted flood risk reduction measures. As such, communities will likely garner broad support to introduce restrictive codes to limit flood exposure, especially in extremely vulnerable areas. The newly implemented Risk Rating 2.0 (Congressional Research Service, 202454) mirrors this recommendation. FEMA recognized the limitations of using static flood hazard maps to determine flood insurance premiums. With Risk Rating 2.0, more variables are incorporated to provide a more detailed differentiation of flood risk.

Future Research Directions

This pilot study was limited to five Virginia communities. The results confirm the value of this type of inquiry. I plan to expand this research to more communities. I also hope that this work will stimulate more research on this topic. In this study, I did not analyze the relationship between community factors and the scope and standards of floodplain zoning. Existing literature has documented that organizational capacity, past flood experience, expected future flood conditions, policy entrepreneurship, and socio-economic characteristics are important determinants of hazard mitigation policy innovation and adoption (Brody et al., 2010; Siders & Keenan, 202055; Wang & Zhang, 202356). Future work should examine the internal and external factors that drive the observed variations in floodplain zoning.

Acknowledgements. I would like to thank Kristin Owen, the Virginia Floodplain Management Association, and Matthew Simmons from the City of Norfolk for their input on this project.

References

  1. First Street Foundation. (2021, February). The cost of climate: America's growing flood risk. https://assets.firststreet.org/uploads/2021/02/The_Cost_of_Climate_FSF20210219-1.pdf ↩

  2. Qiang, Y. (2019). Flood exposure of critical infrastructures in the United States. International Journal of Disaster Risk Reduction, 39, Article 101240. https://doi.org/10.1016/j.ijdrr.2019.101240 ↩

  3. Wing, O. E. J., Bates, P. D., Smith, A. M., Sampson, C. C., Johnson, K. A., Fargione, J., & Morefield, P. (2018). Estimates of present and future flood risk in the conterminous United States. Environmental Research Letters, 13(3). https://doi.org/10.1088/1748-9326/aaac65 ↩

  4. National Research Council. (2012). Disaster resilience: A national imperative. The National Academies Press. https://doi.org/10.17226/13457 ↩

  5. Schwab, A. K., Eschelbach, K., & Brower, D. J. (2007). Hazard mitigation and preparedness. John Wiley and Sons. ↩

  6. Bronin, S. (2023). Zoning by a thousand cuts. Pepperdine Law Review, 50, 719-783. ↩

  7. Gray, M. N. (2022). Arbitrary lines: How zoning broke the American city and how to fix it. Island Press. ↩

  8. Federal Emergency Management Agency. (n.d.). NFIPCommunity Status Book. Retrieved October 6, 2024, from https://www.fema.gov/about/openfema/data-sets ↩

  9. Coronese, M., Lamperti, F., Keller, K., Chiaromonte, F., & Roventini, A. (2019). Evidence for sharp increase in the economic damages of extreme natural disasters. Proceedings of the National Academy of Sciences, 116(43), 21450-21455. ↩

  10. Crowell, M., Coulton, K., Johnson, C., Westcott, J., Bellomo, D., Edelman, S., & Hirsch, E. (2010). An estimate of the US population living in 100-year coastal flood hazard areas. Journal of Coastal Research, 26(2), 201-211. https://doi.org/10.2112/JCOASTRES-D-09-00076.1 ↩

  11. Saharia, M., Kirstetter, P. E., Vergara, H., Gourley, J. J., & Hong, Y. (2017). Characterization of floods in the United States. Journal of Hydrology, 548, 524-535. https://doi.org/10.1016/j.jhydrol.2017.03.010 ↩

  12. National Flood Insurance Program Act of 1968, 42 U.S.C. § 4001 et seq. (1968). https://www.fema.gov/sites/default/files/2020-07/national-flood-insurance-act-1968.pdf ↩

  13. Federal Emergency Management Agency. (2005, February). National Flood Insurance Program (NFIP) floodplain management requirements: A study guide and desk reference for local officials (FEMA-480). https://www.fema.gov/sites/default/files/documents/fema-480_floodplain-management-study-guide_local-officials.pdf ↩

  14. Horn, D. P., & Brown, J. T. (2018). Introduction to the National Flood Insurance Program (NFIP). Congressional Research Service. ↩

  15. Criteria for Land Management and Use, 44 C.F.R.§ 60 (1979). https://www.ecfr.gov/current/title-44/chapter-I/subchapter-B/part-60 ↩

  16. Federal Emergency Management Agency. (2017). National Flood Insurance Program community rating system: Coordinator’s manual (FIA-15/2017). https://www.fema.gov/sites/default/files/documents/fema_community-rating-system_coordinators-manual_2017.pdf ↩

  17. Brody, S. D., & Highfield, W. E. (2013). Open space protection and flood mitigation: A national study. Land Use Policy, 32, 89-95. ↩

  18. Butler, W. H., Deyle, R. E., & Mutnansky, C. (2016). Low-regrets incrementalism: Land use planning adaptation to accelerating sea level rise in Florida’s coastal communities. Journal of Planning Education and Research, 36(3), 319-332. ↩

  19. Sun, F., & Carson, R. T. (2020). Coastal wetlands reduce property damage during tropical cyclones. Proceedings of the National Academy of Sciences, 117(11), 5719-5725. https://doi.org/https://doi.org/10.1073/pnas.1915169117 ↩

  20. White, G. F. (1936). Notes on flood protection and land use planning. Planning Journal, 3(3), 57-61. ↩

  21. Brody, S. D., Kang, J. E., & Bernhardt, S. (2010). Identifying factors influencing flood mitigation at the local level in Texas and Florida: The role of organizational capacity. Natural Hazards, 52(1), 167-184. https://doi.org/10.1007/s11069-009-9364-5 ↩

  22. Burby, R. J., Deyle, R. E., Godschalk, D. R., & Olshansky, R. B. (2000). Creating hazard resilient communities through land-use planning. Natural Hazards Review, 1(2), 99-106. ↩

  23. Deyle, R. E., Chapin, T. S., & Baker, E. J. (2008). The proof of the planning is in the platting: An evaluation of Florida's hurricane exposure mitigation planning mandate. Journal of the American Planning Association, 74(3), 349-370. ↩

  24. Montz, B. E. (2000). The generation of flood hazards and disasters by urban development of floodplains. Floods, 1, 116-127. ↩

  25. Hudson, P., & Botzen, W. J. W. (2019). Cost–benefit analysis of flood-zoning policies: A review of current practice. WIREs Water, 6(6), e1387. https://doi.org/https://doi.org/10.1002/wat2.1387 ↩

  26. Jepson, E. J., & Haines, A. L. (2014). Zoning for sustainability: A review and analysis of the zoning ordinances of 32 Cities in the United States. Journal of the American Planning Association, 80(3), 239-252. https://doi.org/10.1080/01944363.2014.981200 ↩

  27. Green, S. D. (2016). Zoning neighborhoods for resilience: Drivers, tools and impacts. Fordham Environmental Law Review, XXVIII(1), 41-101. ↩

  28. Averts, J. C. J. H., & Wouter Botzen, W. J. (2011). Flood-resilient waterfront development in New York City: Bridging flood insurance, building codes, and flood zoning. Annals of the New York Academy of Sciences, 1227(1), 1-82. https://doi.org/https://doi.org/10.1111/j.1749-6632.2011.06074.x ↩

  29. Burton, I., Kates, R. W., & White, G. F. (1978). The environment as hazard. Oxford University Press. ↩

  30. Cutter, S. (2005). Are we asking the right question?. In R. W. Perry & E. L. Quarantelli (Eds.), What is a disaster? New answers to old questions (pp. 39-48). Xlibris Publisher. ↩

  31. Peek, L. A., & Mileti, D. S. (2002). The history and future of disaster research. In R. Bechtel & A. Churchman (Eds.), Handbook of Environmental Psychology (pp. 511-524). Wiley. ↩

  32. Brody, S. D., Bernhardt, S., Zahran, S., & Kang, J. E. (2009). Evaluating local flood mitigation strategies in Texas and Florida. Built Environment, 35(4), 492-515. ↩

  33. Doberstein, B., Fitzgibbons, J., & Mitchell, C. (2019). Protect, accommodate, retreat or avoid (PARA): Canadian community options for flood disaster risk reduction and flood resilience. Natural Hazards, 98, 31-50. ↩

  34. Schroeter, S., Richter, H., Arthur, C., Wilke, D., Dunford, M., Wehner, M., & Ebert, E. (2021). Forecasting the impacts of severe weather. The Australian Journal of Emergency Management, 36(1), 76-83. https://doi.org/10.3316/informit.766653620579430 ↩

  35. Jacob, K. H. (2015). Sea level rise, storm risk, denial, and the future of coastal cities. Bulletin of the Atomic Scientists, 71(5), 40-50. https://doi.org/10.1177/0096340215599777 ↩

  36. Birkland, T. A., Burby, R. J., Conrad, D., Cortner, H., & Michener, W. K. (2003). River ecology and flood hazard mitigation. Natural Hazards Review, 4(1), 46-54. https://doi.org/https://doi.org/10.1061/(ASCE)1527-6988(2003)4:1(46) ↩

  37. Mudashiru, R. B., Sabtu, N., Abustan, I., & Balogun, W. (2021). Flood hazard mapping methods: A review. Journal of Hydrology, 603. https://doi.org/10.1016/j.jhydrol.2021.126846 ↩

  38. Burgos, A. G., Hamlington, B. D., Thompson, P. R., & Ray, R. D. (2018). Future nuisance flooding in Norfolk, VA: From astronomical tides and annual to decadal internal climate variability. Geophysical Research Letters, 45(22), 12432-12439. https://doi.org/https://doi.org/10.1029/2018GL079572 ↩

  39. Sweet, W. V., & Park, J. (2014). From the extreme to the mean: Acceleration and tipping points of coastal inundation from sea level rise. Earth's Future, 2(12), 579-600. ↩

  40. Zhang, Y., & Wildemuth, B. M. (2017). Qualitative analysis of content. In B. M. Wildemuth (Ed.), Applications of social research methods to questions in information and library science (2nd ed., pp. 318-329). Libraries Unlimited. ↩

  41. Krippendorff, K. (2004). Content analysis: An introduction to its methodology. Sage. ↩

  42. Berke, P. R., Malecha, M. L., Yu, S. Y., Lee, J., & Masterson, J. H. (2019). Plan integration for resilience scorecard: Evaluating networks of plans in six US coastal cities. Journal of Environmental Planning and Management, 62(5), 901-920. https://doi.org/10.1080/09640568.2018.1453354 ↩

  43. Lyles, W., & Stevens, M. (2014). Plan quality evaluation 1994-2012: Growth and contributions, limitations, and new directions. Journal of Planning Education and Research, 34(4), 433-450. https://doi.org/10.1177/0739456x14549752 ↩

  44. City of Norfolk, Virginia, Zoning Ordinance 2022 Article 12 Section 5. ↩

  45. Grimm, M. (2020, February 27). An examination of federal flood maps in a changing climate [Testimony of Micheal Grimm], U.S. House of Representatives Committee on Science, Space and Technology, Subcommittee on Investigations and Oversight, Subcommittee on Environment. 116th Congress, 2nd Session. ↩

  46. Pralle, S. (2018). Drawing lines: FEMA and the politics of mapping flood zones. Climatic Change, 152(2), 227-237. https://doi.org/10.1007/s10584-018-2287-y ↩

  47. Maxwell, J. K. (2016, August 14). WTH: What the hell is a flood study? [Post]. LinkedIn. https://www.linkedin.com/pulse/wth-what-hell-flood-study-j-keith-maxwell/ ↩

  48. Kodey, A., Bedard, J., Nipper, J., Post, N., Lovett, S., & Negreros, A. (2023, December 13). The US needs more engineers. What’s the solution? Boston Consulting Group. https://www.bcg.com/publications/2023/addressing-the-engineering-talent-shortage ↩

  49. Reid, R. L. (2023, May 1). Why US civil engineering firms face a labor shortage. Civil Engineering Magazine. https://www.asce.org/publications-and-news/civil-engineering-source/civil-engineering-magazine/issues/magazine-issue/article/2023/05/why-us-civil-engineering-firms-face-a-labor-shortage ↩

  50. Berke, P., Newman, G., Lee, J., Combs, T., Kolosna, C., & Salvesen, D. (2015). Evaluation of networks of plans and vulnerability to hazards and climate change. Journal of the American Planning Association, 81(4), 287-302. https://doi.org/10.1080/01944363.2015.1093954 ↩

  51. Cutter, S. L., Barnes, L., Berry, M., Burton, C., Evans, E., Tate, E., & Webb, J. (2008). A place-based model for understanding community resilience to natural disasters. Global Environmental Change, 18(4), 598-606. https://doi.org/10.1016/j.gloenvcha.2008.07.013 ↩

  52. Wing, O. E. J., Bates, P. D., Sampson, C. C., Smith, A. M., Johnson, K. A., & Erickson, T. A. (2017). Validation of a 30 m resolution flood hazard model of the conterminous United States. Water Resources Research, 7968-7986. https://doi.org/https://doi.org/10.1002/2017WR020917 ↩

  53. Federal Emergency Management Agency. (2021. February 21). North Carolina cooperating technical partner agreement. https://www.fema.gov/case-study/north-carolina-cooperating-technical-partner-agreement ↩

  54. Congressional Research Service. (2024). National Flood Insurance Program risk rating 2.0. https://crsreports.congress.gov/product/pdf/IN/IN11777 ↩

  55. Siders, A., & Keenan, J. M. (2020). Variables shaping coastal adaptation decisions to armor, nourish, and retreat in North Carolina. Ocean & Coastal Management, 183, Article 105023. ↩

  56. Wang, Q., & Zhang, Y. (2023). Theorizing hazard mitigation policy adoption: Using floodplain property buyout program as an example. Natural Hazards Review, 24(2). https://doi.org/https://doi.org/10.1061/NHREFO.NHENG-1569 ↩

Suggested Citation:

Zhang, Y. (2024). Zoning for Flood Risk Reduction in Five Virginia Communities: Opportunities to Improve Flood Hazard Mapping and Municipal Practice. (Natural Hazards Center Mitigation Matters Research Report Series, Report 18). Natural Hazards Center, University of Colorado Boulder. https://hazards.colorado.edu/mitigation-matters-report/zoning-for-flood-risk-reduction-in-five-virginia-communities

Zhang, Y. (2024). Zoning for Flood Risk Reduction in Five Virginia Communities: Opportunities to Improve Flood Hazard Mapping and Municipal Practice. (Natural Hazards Center Mitigation Matters Research Report Series, Report 18). Natural Hazards Center, University of Colorado Boulder. https://hazards.colorado.edu/mitigation-matters-report/zoning-for-flood-risk-reduction-in-five-virginia-communities