New Hampshire Chapter of the Construction Specifications Institute


  
Coastal Flood Risk Science and Technical Advisory Panel Releases Science Summary

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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 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 .

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