Assessing My Flooding Risk

From the 1970's inventory of tidal marshes to the thousands of shoreline site visits in the 2000's, CCRM researchers noticed changes in the wetland systems being studied, and worked to figure out why.  More frequent flooding was discovered to be part of the reason for these changes. This research led to several tools to help you understand and reduce your flooding risk; from occasional large weather events to everyday road flooding.

WHAT IS FLOODING?

Flooding is an overflowing of water onto land that is normally dryDepending on the source, the flooding may be predictable, like tidal flooding, or be very unpredictable and vary in frequency, duration and strength, such as rainfall-induced flooding. 

What are the sources of flooding? The most notable forms of flooding come from storm surge, rain, and tides.  Click on an arrow next to a flood variety that you’d like to know more about:

Storm Surge Flooding ...

Storm surge is a dangerous wall of water created by the winds of severe storms like hurricanes, tropical storms, and nor’easters.  These storms can cause Bay and ocean water to pile up before pushing it on shore, sometimes raising water levels by more than 20 feet above normal sea level. 

Storm surge can affect large areas of coastal lands, but the amount of flooding is different with each storm.  The surge height depends on the direction the storm approaches the coast, as well as the strength, speed and timing of the storm.  If the storm hits land near the time of high tide, it would make the storm surge worse.

Along with powerful storm waves that hit the coastline for hours at a time, storm surge can cause major damage as it knocks homes off their foundations, erodes marshes, breaks up dunes meant to protect coastal areas against storms, and floods riverside communities, sometimes even several miles inland.

Rainfall Flooding ...

Rainfall flooding, or surface water flooding, is the flooding of land areas during and after heavy rain.  Floods occur when the ground, storm sewers, ditches, streams, and rivers become overwhelmed causing the extra water to spread out across low-lying and downstream land areas. 

In coastal Virginia, even a relatively small amount of rain can cause flooding in low-lying areas.  There are two main factors that can worsen rainfall flooding:

1) The area is covered by pavement and other manmade surfaces that lack the ability to absorb water.  Ditches and storm sewers in cities and suburbs can quickly fill up, so that flood water has nowhere to soak in or drain to.

2) The ground is already saturated or almost “full” of water.  When an area has several rain storms in a short period of time or a very low ground elevation with a high-water table.  Any additional rainfall can quickly begin ponding above the ground. 

Tidal Flooding ...

Tidal flooding is the temporary flooding of low-lying areas near the coast due to an exceptionally high tide. This kind of flooding, that typically results in less than a foot of water, is happening more often due to gradual sea level rise, land subsidence, and the loss of natural barriers.  

Tidal flooding sometimes happens during full and new moon cycles every month and during annual King Tides, which are the highest tides each year. It is called ‘blue sky flooding’ when it happens on sunny days without a storm event. 

Extreme high tide flood events are sometimes called ‘nuisance floods’ They are common in cities and other developed coastal areas causing inconveniences and nuisances, such as mosquitoes, frequent road closures, overwhelmed storm drains, and structural damage leading to poor water quality, lower property values, and less tourism.

Combination Flooding ...

Often some combination of storm surge, rainfall, and tides will occur at the same time which can amplify the impacts of flooding and increase the uncertainties making it more difficult to successfully forecast.

 

  • A combination of storm surge and high tides is often referred to as storm tides.
  • A combination of storm surge and rainfall is typically called compound flooding.
  • Heavy rainfall during tidal flooding can rapidly lead to coastal flash floods.

Is flooding really a problem?  Yes!  Natural floodplains have been developed and altered, sea level and groundwater tables are rising, precipitation is becoming more intense, and tidal flooding is more frequent.  Storm surge flooding happens more easily because of these higher water levels- all leading to more flooding events that often come at a personal and financial cost.  Evidence of this can be seen in our neighborhoods with recurrent flooding, ghost forests, wetlands gradually appearing within developed areas and previously dry backyards, docks and piers going under water more often, community alerts and flood advisories.

"Impacts from flooding can range from temporary road closures to the loss of homes, property and life. In coastal Virginia, the cost of large storm damage can range from millions to hundreds of millions of dollars per storm." – Virginia Department of Emergency Management

Flood Facts ...

Virginia Flood Awareness Week encourages Virginians to learn about their flood risk and protect the life they’ve built with flood insurance.

  • Floods are the most common and costly natural disaster in our country.
  • 90 percent of all presidential declarations of emergency and major disasters involve flooding.
  • On average, 100 Americans lose their lives in floods each year.
  • On average, flood damages throughout the nation annually exceed $3 billion, and as of January 31, 2019, flood insurance claims in Virginia totaled more than $730 million.
  • Both direct and indirect costs of flood recovery are borne by all American taxpayers, not just flood victims.
  • Virginia has 2.3 million acres of mapped special flood hazard areas, which represents 9 percent of Virginia's land mass.
  • Only 31 percent of people who live in a special flood hazard area have flood insurance.
  • Floods can happen without warning and all Virginians should know their risk.
  • Certain communities, including those of low economic means and communities of color, are disproportionally affected by flooding events.
What is the difference between flooding and sea-level rise?

Numerous weather and human-related factors influence whether or not a flood occurs. However, as the Intergovernmental Panel on Climate Change (IPCC) noted in its special report on extremes, it is increasingly clear that climate change “has detectably influenced” several of the water-related variables that contribute to floods, such as rainfall and snowmelt. So, while Earth’s changing climate may not induce floods directly, it exacerbates many of the factors that do by melting polar glaciers and sea ice, resulting in sea level rise.

"Today, Virginia has 164,000 people at risk of coastal flooding.  By 2050, an additional 137,000 people are projected to be at risk due to sea level rise." – Climate Central

  • Find out why Hampton Roads is so vulnerable to Sea-level Rise. – VIMS "A Deeper Dive", YouTube video (0:41)
  • Learn more about Sea-level Rise.
Find out more about flooding ...
  • Learn more about Nuisance Flooding and why is it becoming a bigger issue in coastal Virginia. – VIMS "A Deeper Dive", YouTube video (0:40)
  • Learn how VIMS is Forecasting Tidal Flooding by using tide gauge data and advanced computer models to generate accurate 36-hour predictions. – VIMS "A Deeper Dive", YouTube video (1:54)
  • Watch how Modeling Storm Surge helps coastal communities be more resilient and improve their economic strength. – VIMS "A Deeper Dive", YouTube video (3:10)
  • Learn about the AdaptVA web portal with tools and resources to help individuals and coastal communities think differently about how they live, work, and play along the coast. – VIMS Marine Science Day 2021, YouTube video (21:34)
  • Read about Forecasting Coastal Water Levels in Virginia – Rivers & Coast, 2018 (pdf)
  • Discover more about future flooding issues and adaptation strategies for reducing the impact of flood events in the Recurrent Flooding Study – Rivers & Coasts, 2012 (pdf)
  • Watch this example of adapting to flooding - a shed built on a floating platform designed to rise during floods without releasing the contents stored inside. – YouTube video (:06)
  • These adaptations were added in the Carl Hershner Teaching Marsh to help protect water quality and marsh habitat as well as improve access for learning.
I'M GOING TO MOVE, WHAT DO I NEED TO KNOW?

When considering a new home it is always a good idea to look into current and future flood potential! 

STEP 1 – Is there potential to flood TODAY?

Weighing a decision to move starts with gathering information on the property and general area.

Is the home or address in a Flood Hazard Zone?

Knowing the location of flood zones helps property owners and buyers understand their flood insurance rate and consider floodproofing options; assists insurance agents in assessing rates; and offers builders insight on potential building restrictions and standards.

Find your flood zone:

FEMA floodplains are the areas likely to flood during the 100- and 500-yr flood events and are based on current and historic conditions (without consideration of potential sea level rise along a shoreline).

  • Go to the Virginia Flood Risk Information System (VFRIS)
  • Enter an address or location into the "Find Address or Place" toolbar above and press enter.
  • Click on your area of interest. A popup will appear with FIRM panel and FEMA Floodplain results.
  • Use the arrows at the top of the pop-up to find the "Flood Hazard Zone" window. From there the field "Flood Zone" will indicate your flood zone.
What do the zones mean?

The 100-year storm (1% annual chance flood hazard) is noted by AE and VE zones. The VE portion can be subject to heavy wave action during storm events. Generally, if the property is not located in Zone-X you should purchase flood insurance. 

Keep in mind that, Will my property flood? is not the same as, Do I need flood insurance?  If it is raining your property has the potential to flood.  You should always contact your insurance agent to be sure.

FEMA Zones: (area, description, zone)
Regulatory Floodway

The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height.

Within Zone AE

Special Flood Hazard Area (SFHA)

The area that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. This area is also referred to as a 100-year floodplain.

All A and V zones (Zone A, Zone AO, Zone AH, Zones A1-A30, Zone AE, Zone A99, Zone AR, Zone AR/AE, Zone AR/AO, Zone AR/A1-A30, Zone AR/A, Zone V, Zone VE, and Zones V1-V30)

Area of Moderate Flood Hazard

The area between the limits of the 1 percent flood and the 0.2 percent of being equaled or exceeded in any given year. This area is also referred to as a 500-year floodplain.

X (shaded) and Zone B

Area of Minimal Flood Hazard

The area is outside the SFHA and higher than the elevation of the 0.2 percent annual-chance flood.

Zone X (unshaded) and Zone C

Area of Undetermined Flood Hazard

The area with a possible, but undetermined flood risk, as no analysis of flood hazards has been conducted.

Zone D

Area of Reduced Risk Due to Levee

The area protected by a levee, reducing the flood risk, so long as the levee is properly maintained.

Zone X with reduced risk due to levee

Will some portion of the road network be underwater?


When relocating, it is helpful to know how often road flooding will affect your ability to get to work or to the store and, for emergency vehicles to reach your home.  A Locality Road Flood Tool shows how flood frequency will impact travel to a particular road from the County Seat under different flood levels.

Check road access near you:
  • Go to Locality Road Flood Tool
  • At the top of the page click on your area (for example Middle Peninsula).
  • Zoom into your area of interest.
  • If the road is pink, that tells you that some part of the road goes underwater whenever there is 2-3 feet of flooding.  If the road is yellow, orange or red, it only floods during more extreme flood events.
How often does the property flood?

Considering whether the property floods daily or only occasionally can help you to compare the benefits with potential financial costs and emotional hardships.  Flood frequency is displayed in this tool as the number of hours of flooding (over the past 19 years) based on tide gauge data - capturing areas of regular tidal flooding (floods daily), high tide flooding (floods occasionally) and storm surge flooding (floods a few hours per year).

See how often the property floods:
  • Go to Locality Road Flood Tool
  • At the top of the page click on your area of interest (for example Middle Peninsula).
  • Zoom into your area of interest.
  • On the menu on the left, click the eye next to “Flooding Duration Maps” to display the layer.  
  • Click the arrow next to “Flooding Duration Maps” to open the options. Make sure the eye next to “Current Flooding Duration:2020” is open, and the other 2 options have slashes through the eyes. The different colors indicate different flooding frequencies, with darker colors meaning more time underwater each year. The light blue color covers areas that only flood during a larger storm events. The medium and dark blue colors show areas that flood more frequently during unusually high tides.
STEP 2 – Is there MORE potential to flood in the FUTURE?

Understanding the trajectory of change can help us predict and possibly avoid, or prepare and hopefully defend against future flooding.

Sea-level rise ...

Sea level rise is the rate of change in the average sea level, or the average water level between high tides and low tides. The potential for future flooding can be predicted by the amount of sea level rise expected at any given location.

Check the expected change in sea-level rise near you:
  • Go to AdaptVA Sea-Level-Rise Viewer.
  • Put your address in the white box at the top left of the map.
  • Click on the “Sea Level Rise/Flooding/Storm Surge” blue button at the lower left bottom of the map.
  • Check the box next to “Sea Level Rise (mean high water)”.
  • On the very bottom of the map is a time slider, drag the blue circle forward in time to see the predicted sea level change. Extreme high tides and storm surge flooding can extend further inland from typical high water level.
Forecasted flood frequency ...

Flooding duration maps combine hours of flooding (over the past 19 years) based on tide gauge data with projected sea level rise to forecast what to expect for future flooding.

Check the likelihood of a property flooding in the future:
  • Go to Locality Road Flood Tool
  • At the top of the page click on your area of interest (for example Middle Peninsula).
  • Zoom into your area of interest.
  • On the menu on the left, click the eye next to “Flooding Duration Maps” to display the layer.  
  • Click the arrow next to “Flooding Duration Maps” to open the options. Click on the eye next to “Projected Flooding Duration:2050” to open the layer. Make sure the other 2 options have slashes through the eyes. The different colors indicate different flooding frequencies, with darker colors meaning more time underwater each year. The light blue color covers areas that only flood during larger storm events. The medium and dark blue colors show areas that flood more frequently during unusually high tides. Click on any point of the blue layer to see the depth of the water over the land under projected sea level rise.
STEP 3 – Seek Expert Advice

For on-site answers to questions concerning your specific property contact these 'in-the-know' professionals:

Virginia Department of Health
The Virginia Department of Health will provide drinking water and septic system records for the property you are interested in.  The records include permit information, inspection reports, as-built drawings, and enforcement-actions.  The inspectors can tell you if well and septic systems in the area are prone to flooding issues, exactly what type of septic system serves a particular property and suggest some resources for alternative septic systems.
Your Insurance Agent
Your insurance agent can tell you if the property is in a flood zone, if you should consider flood insurance and how much it will cost.  If the property is in a flood zone, flood insurance might be required to qualify for a mortgage and can be very expensive.  If the property is not in a federally designated flood zone but near the water you may still prefer to have flood insurance for peace of mind as it can be relatively inexpensive.
Your Real Estate Agent
Virginia is a “buyer beware” state leaving it up to the buyer or renter to find out if the property is at risk of flooding.  In many states, the law requires a home seller to disclose to a potential buyer any problems or defects known about the home.  In Virginia, the seller must provide the buyer with a Residential Property Disclosure Statement, (Code of Virginia § 55.1), but it essentially just tells the buyer that it is their responsibility to find any problems prior to closing. Fortunately, your real estate agent will be familiar with the area and should know to what extent flooding should be a concern.
Local Government Officials
Contact the local town, city or county environmental or planning office where the property is located for assistance looking up the current and future flood potential before purchasing real estate.  Many localities have interactive map viewers on their web sites that provide useful property information.
I LIVE IN A FLOOD PRONE AREA, NOW WHAT?

Preventing ...

Coastal resilience practices, such as living shorelines, protect both humans and natural systems by minimizing wave energy associated with flood events.  Natural and nature-based features and accommodating marsh migration are best practices to alleviate the effects of tidal flooding. 

See what is recommended for the unstabilized part of your shoreline:
  • Go to Shoreline Management Model Viewer
  • Put your address in the white box at the top left of the map.
  • Click on the “Shoreline Management” blue button at the bottom of the map.
  • Check the box next to “Shoreline Management Model”. Colored lines will appear. 
  • Click on a line to see the recommendation associated with it.
Adapting ...

Flood adaptation refers to ways to reduce your risk, vulnerability, and/or human and economic consequences from flooding events.  See the storymaps below that explain how localities worldwide implement the three main types of flood adaptation:

  1. Management/Retreat, when natural forces are allowed to continue to function and human impacts are minimized by avoiding, minimizing or regulating human use of the coastal area.
  2. Accommodation, when people continue to use and occupy the coastal zone, but adapt their lifestyle to reduce flood impacts; (like managing transportation and water storage). 
  3. Protection, when structural (hard or soft) engineering aims to protect the land from the water.
The most common adaptive approach to flooding in coastal Virginia currently is accommodation, which includes raising buildings and roads, establishing evacuation routes and warning systems, and creating or enhancing stormwater systems.
Understanding issues with septic systems ...

Homes located in the coastal area of Virginia must contend with rising groundwater levels and recurrent flooding, making septic systems there vulnerable. Even well-maintained septic systems will deteriorate over time and can discharge into adjacent waters. 

Find out more here...

For more information, contact your local Virginia Department of Health inspector.  They are very familiar with the areas that they work in and can suggest some resources if alternative septic systems are required. 

Preparing for storms ...

When a storm is approaching there are many questions to answer like, Will the road to my house be flooded tomorrow at high tide?  At what time should I expect coastal flooding near me?

Water level forecasts shift with the tides by the hour. This Tidewatch tool makes it easier to visualize and time impacts to roads, properties, and structures over the next 36 hours based on current tidal, weather and storm-surge conditions.

See what tidal flooding will look like in the next 36 hours:
  • Open Tidewatch Map (this will take a minute to load)
  • Put your address in the white box at the top left of the map.
  • Click the arrows on the time slide bar to see forecasted water levels either 6am to 6pm the following day OR 6pm to 6am the day after tomorrow.
  • Click anywhere on the map to open a chart with two lines: water elevation over the next 36 hours and the land elevation at that location.
  • Additional information about VIMS Tidewatch can be found here.
Deciding when and how to evacuate ...
The Virginia Department of Emergency Management encourages all residents to Know Your Zone long before a serious storm threatens Virginia’s coastal region.  Tiered evacuation zones are designated A through D.  Local emergency managers will broadcast instructions for these zones for evacuation and what routes to take, or for sheltering in place.
WHAT CAN WE DO TO HELP?

What can YOU do?

Learn how to help, volunteer to do more, and share what you know ...

Think Green ...

Learn more about what you can do to protect natural flood-reducing features and replace hardscapes at home and in your community with greener options and encourage others to join you!

  • Identify and protect natural wetlands in the local area
  • Protect coastal forests and make connections between forest patches
  • Learn how to Plant Virginia Natives that are suitable for coastal landscapes
  • Allow leaves and sticks to remain under trees to promote water soaking into the ground
  • Convert turf and impervious areas near the water into forests and planted areas
  • Sign up to participate in local Go Green programs like askHRgreen.org
Volunteer ...
"Catch the King" is the world's largest environmental survey.  With the goal of improving predictive models and the future forecasting of "nuisance" flooding, citizen scientists use GPS to collect flood data during the King Tide (the highest yearly tidal event) throughout coastal Virginia. Sign up to help!
Get Involved ...
Encourage your locality’s elected officials to enroll in the FEMA Community Rating System for lower flood insurance premiums
What are CCRM and VIMS doing?

CCRM is researching flooding, creating models to predict flooding, and checking the accuracy of our models by collecting real-time flooding data and comparing it to the model forecasts.  Find out more about our work on adaptation and management, flooding models and the tools that are available to help you predict flooding where you live.

Informing Policy ...
Review the Recurrent Flooding Study for Tidewater Virginia that identifies recurrent flooding issues throughout Tidewater Virginia, examines future flooding issues and evaluates adaptation strategies for reducing the impact of flood events.(Report submitted to the Virginia General Assembly January 2013)
Commonwealth Center for Recurrent Flooding Resiliency ...
The Virginia Institute of Marine Science, the College of William & Mary, and Old Dominion University, have established CCRFR the Commonwealth Center for Recurrent Flooding Resiliency. The Center provides a one-stop shop for supporting the Commonwealth, state agencies, localities, and other entities with scientific and technical support in furtherance of recurrent flooding resiliency.
Storm Central ...
VIMS Storm Central is a one-stop shop for information on how the Virginia Institute of Marine Science (VIMS) helps our community understand and address the coastal impacts of hurricanes and nor'easters. During storm events, we also offer data streams, videos, and photos as conditions allow. 
What is VIRGINIA doing?

Policymakers have implemented a number of regulations to help preserve natural resources and protect the public.

Flood Awareness Week ...
Governor Ralph Northam designated March 14-20 Virginia Flood Awareness Week, encouraging Virginians to learn about their flood risk and protect the life they’ve built with flood insurance.
Floodplain management policy ...

"Flooding remains the most common and costly natural disaster in Virginia and the United States. With more than 100,000 miles of streams and rivers, as well as 10,000 miles of estuarine and coastal shoreline, Virginia’s flood risk is statewide, comes in many forms, and is increasing because of climate change and increased development in flood-prone areas."

  • Floodplain Management Requirements and Planning Standards for State Agencies, Institutions, and Property  Executive Order 45 effective November 15, 2019, looks at the risks associated with building in flood-prone areas.