Preparing Communities for Nuisance Flooding and Sea Level Rise

Nov 21, 2018
Photo by: Pat Johnson JCNERRS Manager Lisa Auermuller with a slide from the NJADAPT map prepared by Rutgers using the Total Water Level approach.

Lisa Auermuller is the watershed coordinator for the Jacques Cousteau National Estuarine Research Reserve in Tuckerton. Her duties include assessing the needs of coastal decision makers and providing relevant training opportunities. Her most recent focus is climate change, and coastal communities’ vulnerability to sea level rise. On Monday, Nov.19, Auermuller led a workshop at JCNERRS for municipal flood plain managers, code enforcement and construction officials, and other stakeholders to learn about two mapping tools available to the public through Rutgers University and to give their input on how to best to improve those tools when they are condensed into one.

The maps, NJAdapt and NJ Floodmapper, were developed through the Rutgers Center for Remote Sensing and Spatial Analysis. The interactive maps have layers and menus to enhance the ability of coastal planners and emergency management officials to prepare for nuisance and storm flooding.

They also help communities understand their risks, plan for those risks and put adaptation measures into place.

On Monday, about 20 officials from Ocean and Atlantic counties gathered at the JCNERRS Educational Center on Great Bay Boulevard in Tuckerton. Locally, Ship Bottom Councilman Robert Butkus, Long Beach Township construction official Dane Sprague and Tuckerton Waterways Commission Chairwoman Nedean Maddox were in the audience, as well as Chris Huch of local nonprofit Alliance for a Living Ocean and a Tetra Tech employee.

Auermuller re-acquainted the stakeholders with the features of the maps that include individual towns’ impacts by multi-year sea-level rises, areas that experience coastal flooding impacts and storm surge based on Category 1-to-5 hurricane events. There is an ability to look back to the storm surge and economic impacts of 2012’s Superstorm Sandy. The ability to use slide bars to scale data and maps to different scenarios can help stakeholders gauge trends and prioritize future actions. For example, a municipality may want to move its emergency services out of its flood zone or locate a shelter on a school on higher ground.

If one believes the 2016 Rutgers Climate Adaptation Alliance best estimates for sea level rise (8 inches by 2030, a foot by 2050), emergency access roads may need to be raised.

JCNERRS received a grant to merge the two separate websites into one, and that process will be done by September 2019. “There were too many tools; it was confusing. When we bring them together into one, we want to improve it wherever we can,” said Auermuller.

The stakeholders were asked to suggest improvements. Dane Sprague asked if the maps could include the new LIMWA line as well as the FEMA V-zone line. LIMWA stands for Limit of Moderate Wave Action. Houses within the V-zone (high wind and 3-foot wave zone) generally cost more for flood insurance. A newly created zone, the LIMWA is based on the probability of a 1½-foot storm surge occurring during a so-called 100-year storm. People whose homes are in the LIMWA zone will pay as much for flood insurance as those in the V-zone.

Other data that would be helpful would be a map showing homes that are now flood zone compliant versus those still subject to flooding; local mitigation projects that have been completed and infrastructures not yet on the map, such as wastewater infrastructure and water supply wells. There was a request for adding endangered species habitat and Green- and Blue-Acres properties.

One of the biggest problems on the maps’ forecasting impacts to various municipalities on the bayside is the lack of NOAA tide gauges. There are many tide gauges on the bayside, but none are as reliable as the NOAA gauges, of which New Jersey has only four: New York/New Jersey bight, Sandy Hook, Atlantic City and Cape May – and they are all on the ocean side.

So getting a picture of how the combined impacts of high tide, sea level rise and storm surge would affect our local municipalities on the back bays is based on the NOAA tide gauge in Atlantic City. Still, it’s a better forecast than nothing.

Auermuller showed how a town could view “Total Water Levels” for its town, starting with a normal high tide, adding the effect of a full moon, sea level rise (depending on what year is cued in), and storm surge from a category 1-to-5 storm. This is a scary exercise for those not at flood level compliance.

Many of the municipal stakeholders invited to the workshop said old-timers know to check the moon phase, wind direction and high tide charts in advance of a storm, but visitors to the shore remain clueless and do not know about moving their cars. A better advance-warning system is needed.

According to records from the Atlantic City tide gauge for 2017, there were 52 nuisance-flooding events where the tide advanced a foot above the mean high water mark. Nine tide cycles in 2017 were 2 feet above MHW, and once the tide was 3 feet above MHW.

Storm surge during Superstorm Sandy was 9.4 feet.

Construction and town officials from Long Beach Island said there is a problem on the Island with homeowners enclosing their pilings and then building unauthorized rooms in the flood-prone area. “You see them raise the house, put the flood vents in and then a year later it’s a (illegal) three-bedroom area with a kitchen and bathroom,” said one.

A few shore towns are doing annual inspections to stem the tide of these illegal conversions: Sea Isle, Margate and Ventnor.

The next steps for the interactive flood map will be for the Rutgers team to take the suggestions from this workshop, add them to the three others and then have the same stakeholders test out the improved map. “Then in 2019 we will launch the new and improved flood map,” said Auermuller.

— Pat Johnson

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