Coastal Flood Risk Science and Technical Advisory Panel Releases Science Summary and Requests Public Input on Draft Guidance

FOR IMMEDIATE RELEASE
DATE: September 3, 2019
CONTACT: Nathalie Morison, NHDES Coastal Program, (603) 559-0029
des.nh.gov
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Portsmouth, NH – On behalf of the 2019 New Hampshire Coastal Flood Risk Science and Technical Advisory Panel (STAP) Steering Committee, the New Hampshire Department of Environmental Services (NHDES) is pleased to announce the publication of the New Hampshire Coastal Flood Risk Summary, Part I: Science (Part I), as well as a request for input on the DRAFT New Hampshire Coastal Flood Risk Summary, Part II: Guidance for Using Scientific Projections (Part II).

Pursuant to RSA 483-B:22, NHDES has convened representatives of the NH Department of Transportation, NH Division of Homeland Security and Emergency Management, NH Office of Strategic Initiatives, NH Department of Administrative Services, NH Fish and Game, NH Department of Natural and Cultural Resources, Rockingham Planning Commission, Strafford Regional Planning Commission, and the University of New Hampshire to supervise an update of storm surge, sea-level rise, precipitation, and other relevant projections originally summarized in the 2014 report to the New Hampshire Coastal Risk and Hazards Commission, Sea-level rise, storm surges, and extreme precipitation in coastal New Hampshire: Analysis of past and projected future trends. The 2019 New Hampshire Coastal Flood Risk Summary is comprised of two parts, including a summary of the science (Part I) and guidance for how to use the science in decision-making (Part II – DRAFT).

Published today by University of New Hampshire researchers, Part I of the New Hampshire Coastal Flood Risk Summary summarizes best available science relevant to coastal flooding in New Hampshire and includes updated projections for relative sea-level rise, coastal storms, groundwater rise, and extreme precipitation. Key findings from Part I are provided below and described in more detail in the report.

• Melting land based glaciers and ice sheets are now the major contributor to sea-level rise;

• Relative sea level in New Hampshire is rising and is projected to rise for centuries; for example, relative sea level is likely to rise between 0.5-1.3 feet by 2050 and between 1.0 – 2.9 feet by 2100 if global greenhouse gas concentrations stabilize; however, there is a risk of much greater sea-level rise if global greenhouse gas concentrations continue to grow and the rate of ice mass loss from Antarctica accelerates rapidly.

• Impacts from storm surge in coastal New Hampshire will increase with relative sea-level rise;

• The frequency of extreme precipitation events is projected to increase over the course of the next several decades, especially in the springtime.

• Mean groundwater levels are expected to rise as a percentage of relative sea-level rise;

• Freshwater flooding is expected to increase in the future.

Part I was reviewed by an external panel of regional experts, including representatives from the Northeast Regional Climate Center at Cornell University, Massachusetts Institute of Technology, Purdue University, Rutgers University, U.S. Geological Survey, HydroAnalysis, Inc., and the National Oceanic and Atmospheric Administration.

Part II of the New Hampshire Coastal Flood Risk Summary builds on Part I and provides DRAFT Guidance for using the scientific projections of coastal flood risks in New Hampshire. The DRAFT Guidance presents overarching principles and a step-by-step approach for incorporating projections for relative sea-level rise, coastal storms, groundwater rise, and extreme precipitation into state and local land use planning and decision-making. The DRAFT Guidance also includes tools to facilitate the use of the scientific projections, including a worksheet and a Sea-Level Rise Mapper.

The 2019 New Hampshire Coastal Flood Risk STAP Steering Committee is seeking input on the DRAFT Guidance throughout the month of September. Interested state and local government officials; professional planners; consultants involved in land use planning, zoning, permitting, land development, conservation, and natural resources management; and members of the public are encouraged to attend free public workshops to provide input on the DRAFT Guidance.

The Public Input Workshops will be held on:

Light refreshments will be provided at both workshops. Interested parties can register for a public input workshop by clicking on the links above.

If you cannot attend a workshop or if you would like to provide additional input following a workshop, written comments on the DRAFT Guidance may be submitted via an online survey.

The deadline to submit comments on the DRAFT New Hampshire Coastal Flood Risk Summary – Part II: Guidance for Using Scientific Projections is Monday, September 30 at 4PM.

For more information, please visit the New Hampshire Coastal Flood Risk Summary website or contact:

Nathalie Morison
Coastal Resilience Specialist
NHDES Coastal Program
603-559-0029
nathalie.morison@des.nh.gov

Funding for this project was provided by the National Oceanic and Atmospheric Administration Office for Coastal Management under the Coastal Zone Management Act in conjunction with the NHDES Coastal Program.