Flood Science Weather

CNC Launches Community Flood Information System ahead of Hurricane Delta

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October 6, 2020

As Hurricane Delta barrels towards the Gulf Coast, CNC Catastrophe and National Claims will deploy a Community Flood Information System (CFIS) to track the extent of flooding in coastal locations. Delta has blown up into a category-4 hurricane today with maximum sustained winds of 140 mph, as of the National Hurricane Center 200PM advisory. It is forecast to slam into the Yucatan Peninsula Wednesday morning, then move into the Gulf of Mexico as a major hurricane.

Hurricane Delta has intensified into a category-4 hurricane as it approaches the Yucatan Peninsula. This infrared satellite picture from the University of Wisconsin shows the area of coldest cloud tops, associated deep convection, in red.

The CFIS project follows a successful project launch for Tropical Storm Beta in Texas last month. During Beta, CNC deployed four flood meters at flood-prone homes in Galveston and Sea Isle, Texas. The meters measured flood depth above ground and also above the North American Vertical Datum of 1988 (NAVD88), the scale used for most elevation certificates.

Flood water from Tropical Storm Beta’s storm surge inundated sections of Galveston, Texas, in September, 2020. Photo: Dr. Hal Needham.

Converting all flood levels to a common datum, or vertical reference, enables for quick and accurate flood impact assessment. For example, residents who evacuated could compare local flood levels to the first floor elevation on their elevation certificate to find out if their home likely flooded. In coastal communities, where many vacation homes and rental properties exist, this system also provided valuable insight for people wanting to check the flood risk of their property from a distance.

The CFIS for Tropical Storm Beta relied upon citizen scientists reporting flood observations every three hours from flood meters installed at their homes. Beta did not threaten the project area with high winds, so many people in elevated buildings stayed home and provided regular updates. One couple, who were celebrating their 47th wedding anniversary, faithfully submitted flood photos every three hours- even at 3:00AM!

Jim and Pat Eggler volunteered as citizen scientists during Tropical Storm Beta. They took photos of the flood meter, installed on the right side of the photo, every three hours during the storm, even while celebrating their 47th anniversary! Photo: Dr. Hal Needham.

These real-time observations enabled CNC to create flood inundation maps that estimated the water depth above ground level in the community. These maps helped people assess the likeliness of flooding inside buildings in the project area.

As we deploy flood meters in coastal communities for Hurricane Delta, we are interested to find citizen scientists who would partner with us to help collect community flood data. Participants need to have an elevation certificate that was professionally surveyed so we can calibrate the flood meters.

CNC created flood inundation maps during Tropical Storm Beta, using data from the Community Flood Information System. Map credit: Aaron Flores and Dr. Hal Needham.

As personal safety is top priority, we are partnering with observers who live in lower wind/ flood impact areas or who have already determined to stay through the storm for personal reasons outside of our project. We will also install one streaming flood meter that sends time lapse photos of flood levels from a GoPro device through the cellular network, making it possible to collect real-time flood data without an observer present.

This technology may provide the world with the first snapshot of Delta’s peak surge level if deployed in the location of highest storm surge.

We are most interested to collect data from locations that do not have a NOAA tide gauge, to help fill in the data gap. The locations listed below are of highest priority….if you live in one of these areas and would like to be involved, please reply to this post or email Hurricane Hal at halneedham@cnc-resource.com.

Vermillon Bay/ Cypremort Point, Louisiana

Houma/ Cocodrie, Louisiana

Mandeville/ Slidell (North Shore), Louisiana

Gulfport/ Biloxi, Mississippi

Water levels reached 18.5 inches above the bulkhead and 66.5 inches above NAVD88 datum according to this photo submitted by Jim and Pat Eggler during Tropical Storm Beta.

This project was made possible through a grant provided to CNC Catastrophe and National Claims from the Northern Gulf of Mexico Sentinel Site Cooperative, in partnership with Dauphin Island Sea Lab. These entities funded a project titled, Improving Flood Resiliency in Biloxi’s Economic Development Corridor, which constructed the first comprehensive flood history for Biloxi, while creating elevation data for more than 900 buildings in the city.

The project identified monitoring flood levels as a challenge because Biloxi does not have a NOAA tide gauge. The new CFIS project helps Biloxi and other cities in the region monitor flooding because the flood meters are mobile and easily installed anywhere along the Gulf Coast.