How to Prepare Your Home Against Hurricane Flood Damage

By Vernon Trollinger, July 30, 2013, Hurricane Prep

DowntownLakeCharlesLAHurricaneIkeSimminchBefore a hurricane strikes, it’s important for a homeowner to know if they are going to be hit with potential flood damage. Hurricane flooding is not limited just to coastal areas. Hurricanes are huge storm systems capable of sending powerful winds and driving rain hundreds of miles inland. For example, on October 29, 2012, Hurricane Sandy was over 1,000 miles wide before it came ashore from the Atlantic Ocean, is was dropping steady rain as far west as central Ohio (according to this helpful chart).

Through Wind and Rain

Hurricane winds cause flooding through storm surges. These occur along coastal areas and regions with large estuaries that can reach hundreds of miles inland. These include Galveston Bay in Texas, the Chesapeake Bay in Virginia, and the bays of the Port of New York and New Jersey. Hurricane winds pile up sea water pushing on the ocean surface. As a result, water is added to the height of the normal tide and is known as a storm tide. When storm tide comes ashore, some of it will remain in the ocean because it’s at the normal tidal height.

Let’s say today’s normal tide height is 2 feet. Hurricane winds add 15 feet on top producing a 17-foot storm tide. When the storm tide hits the shoreline, it loses that 2 feet of normal tide to the shore’s normal contour, but sends the 15 feet of extra ocean water surging inland. Storm tide height changes with time depending on whether the tide is high or low and the movement of the hurricane. The worst case is when a hurricane has generated a storm tide during a normal high tide. The effects of the flood damage are devastating (NOAA animation) enough to make the idea of flood protection seem impossible.

The Danger of Flash Floods

Hurricane rains cause flash flooding by overwhelming the drainage capacity of streams and rivers. Unlike normal river floods that build over weeks, hurricane flash floods dump weeks’ worth of rain in a matter of hours, spilling streams and rivers out of their banks and inundating floodplains. This rarely leaves any time for traditional flood protection activities like sandbagging.

HurricaneIkeWaterLineAdamBaker

All the same, the higher in elevation your home is from the floodplain, the less likely it will be flooded. USGS defines a floodplain as “a strip of relatively flat-lying land that borders a stream and is underlain by sediment carried by the stream and dropped in the slack water beyond the influence of the swiftest current.” On flood maps, certain elevations are shown with benchmarks, the most common being the “100-year flood”. The name is misleading because it sounds like a flood only occurs once every 100 years. The true meaning is statistical shorthand used by USGS for a 1-in-100 chance of flooding to that elevation every year. If local flood maps show your home is situated on “100-year floodplain”, you have a 1-in-100 chance of experiencing a flood every year.

Of course, having hurricanes roll through raises the odds. For example, flooding from Hurricanes Allison (2001) and Ike (2008) in Harris County (Houston) Texas has caused some experts to reconsider the elevation of its 100-year benchmarks and might force the county to redraw its flood maps. According to the Harris County Flood Control District, “A major flood still occurs somewhere in Harris County about every two years.”

Is Your Home at Risk for Flooding?

To prepare your home with protection against hurricane flood damage, first, find out if it is located on a floodplain. Contact your municipal or county building inspection office to learn if your home is located in flood area and if so, learn it’s base flood elevation (BFE). You can also learn from municipal flood maps the type of flood zone it may be in, such as a 100-year-flood zone. Homes located near lakes, streams, or rivers are designated as “A” zones. Beachfront homes and other areas that are at risk from ocean waves and wind (storm surges) are designated “V” zones and frequently have special requirements to elevate the house on piers or pilings.

Next, take advantage of flood monitoring sources. NOAA and USGS maintain flood monitoring websites that provide real-time data for your area:

For New York and Pennsylvania, check out the Mid Atlantic River Forecast Center.

For Texas, go to the West Gulf coast River Forecast Center.

You can also download NOAA’s National Flash Flood Map to see which areas in your region are prone to flash flooding. Or find flood maps for your area on the FEMA website.

Prepare Your Home Before the Hurricane

Once you’ve learned about your risk from local flood maps, The Institute for Business and Home Safety recommends a few of these best practices to reduce flood damage expense:

  • Use water-resistant building materials in areas below the base flood elevation.
  • Leave the basement or lower floors unfinished if they’re below base flood elevation.
  • Install basement electrical outlets above base flood elevation.
  • Prevent sewer backups by installing backflow valves or standpipes.
  • Raise your washer and dryer and other equipment such as the water heater, oil tanks, furnace and electrical wiring on concrete blocks, above the base flood elevation level.
  • If you are unable to raise a particular item, consider anchoring it and protecting it with a flood wall or shield.
  • Install flood proofing such as flood shields, floodgates, or built-up barriers for basement windows and doors. The tops of shields and barriers should extend above the base flood elevation.
  • Install and maintain a sump pump system if you have below-grade floors.
  • Landscape with native plants and vegetation that resist soil erosion.

Downtown Lake Charles, LA after Hurricane Ike image courtesy of simminch.

Hurricane Ike Water Line image courtesy of Alpha Tango Bravo / Adam Baker.

Be Sociable, Share!

Related Posts

Tags: ,








Comments are closed.