PORTSMOUTH – A new report released by the New Hampshire Department of Environmental Services Coastal Program and its partners titled “A Summary of High Tide Flooding Recorded by the Hampton, New Hampshire Tide Gauge: 2013-2020,” outlines the frequency of high tide flooding. . in Hampton, New Hampshire, based on analysis of a tide gauge at Hampton Harbor, which was installed in December 2012. Analysis shows that between 2013 and 2020, at least one high tide flood has occurred produced on 36% of all days recorded by the tide gauge. High tide flooding is defined as high tide exceeding the local 10 foot high tide flood threshold referenced to mean lower low water (MLLW). In low-lying areas of Hampton, floodwaters inundate roads and local properties when water levels reach 10 feet above the MLLW.
Unfortunately, sea level rise is expected to significantly increase the frequency and severity of flooding in coastal areas of Hampton, NH. The 2020 New Hampshire Coastal Flood Risk Guidance recommends that the New Hampshire coast plan for sea level rise of 1.3 to 2.3 feet above 2000 levels by 2050. The summary report of the Hampton Tide Gauge estimates that with 1 foot of sea level rise, 65 percent of the high tides that occur in Hampton could meet or exceed the 10 foot MLLW threshold for high tide flooding, and with 2 feet of sea level rise, 95% of high tides would exceed the 10 foot MLLW threshold for high tide flooding. Between 2013 and 2020, the tide gauge recorded only one flood event to reach the “Major” flood threshold above 13 feet MLLW during the Nor’easter of January 2018. However, with 2 feet of sea level rise, “Major” flood events could occur 27 times a year, on average. More detailed coastal flood modeling work is underway to better understand future flood frequencies and severities expected in Hampton and other New Hampshire coastal communities.
The report’s findings confirm that residents, visitors, local decision-makers and emergency management officials should refer to the Hampton Harbor tide gauge, 3-day forecast and real-time information that factors in weather conditions. in addition to the more commonly used NOAA annual tidal forecast. charts to improve understanding and responses to coastal flood risk. The Hampton Harbor tide gauge supports real-time forecasts and storm warnings issued for the protection of life and property. Looking to the future, the report’s findings underscore the importance of advanced planning and action to mitigate sea level rise and increased flooding in Hampton and surrounding coastal communities. of New Hampshire. The report findings also confirm the need for continued investment in monitoring water levels and tidal flooding across the region.
“The tide gauge data summary confirms what many Hampton Beach residents already know: high tide flooding is already happening very frequently in their lower neighborhoods,” said Kirsten Howard, resilience program coordinator for the program. coastal NHDES. “The Hampton Harbor tide gauge is a valuable asset that deserves sustained investment and regular analysis to help track high tides and storm flooding as sea levels rise, and with this report we can transmit the data to the people who will use it.”
Since 2013, the Hampton Harbor tide gauge has measured water levels at 6-minute intervals on a near-continuous basis. The report summarizing the gauge data record was released by the Coastal Program of the New Hampshire Department of Environmental Services in partnership with NOAA’s Office of Coastal Management and National Weather Service, the Northeast Regional Association of Coastal and Ocean Observing Systems (NERACOOS), Charybdis Group LLC, and the Seabrook Hamptons Estuary Alliance and is available at this URL: https://www.des.nh.gov/sites/g/files/ehbemt341/files/documents/r- wd-21-15.pdf.
Please contact Kirsten Howard, NHDES Coastal Program Resilience Coordinator at 603-559-0020 or [email protected] with any questions regarding this release and the report.