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Sea Level Rise and Storm Surge Impacts to Roadways Draft Report Now Available

Sea Level Rise and Storm Surge Impacts to Roadways Draft Report Now Available

The Hampton Roads region contains one of the largest natural harbors in the world, making the region an attractive location for ports, military, tourism, and other businesses.  This coastal location also makes many of these regional assets susceptible to projected relative sea level rise (the combined effects of land subsidence and absolute sea level rise) and potential storm surge threats.  

Extreme flooding events currently disrupt transportation networks and will likely become more prevalent as sea levels are expected to rise at an accelerated pace for many coastal regions.  Hampton Roads—second only to New Orleans in terms of vulnerability to sea level rise in the United States—is seeing more frequent storm surges and higher tides than before.  Based on past storm events, Hampton Roads’ east coast location makes it prone to significant storm surges about every four to five years.

Repetitive flooding on roadways and at critical transportation facilities can severely impact travel and hurt regional and local economies.  When streets are impassable during and after flooding events, it often results in damages to personal property and missed work time, which has a crippling effect on communities.  For this reason, it is imperative for Hampton Roads to plan for climate change impacts to transportation infrastructure and to develop adaptation strategies for those facilities.  It is also important to consider the latest projections in sea level rise and storm surge when the region builds new roadway infrastructure or rebuilds existing roadway infrastructure. 

In this study, HRTPO staff has partnered with Hampton Roads Planning District Commission (HRPDC) staff to conduct a comprehensive GIS-based flooding vulnerability analysis for potential sea level rise and storm surge impacts to regional roadways by 2045 (next Long-Range Transportation Plan horizon year). 

Given the uncertainty in how much relative sea level rise will occur over time, current research suggests that 2.0 feet of rise could occur in Hampton Roads sometime between 2043 and 2083. With the forecast year of the next HRTPO Long-Range Transportation Plan being 2045, a 2.0 foot relative sea level rise scenario was conservatively used in this analysis. 

The three scenarios used in the flooding vulnerability analysis were as follows:

  1. 2.0 foot relative sea level rise
  2. 2.0 foot relative sea level rise + 25-year storm surge
  3. 2.0 foot relative sea level rise + 50-year storm surge

Within the draft report, results are presented in regional and subarea maps for each Hampton Roads jurisdiction.  The results show that roadways in the Cities of Poquoson, Hampton, Portsmouth, Norfolk, Gloucester County, Chesapeake, York County and Virginia Beach are most vulnerable to potential future relative water rise. 

Click Here to view an interactive map of the draft results.

The results showed that in many cases, very small sections of the road are expected to flood.  Even though a majority of the road itself may not flood, if a small section is inundated with water, a large portion of that roadway may be unusable. 

Furthermore, the analysis showed that, under the three sea level rise/storm surge scenarios, many bridges were not expected to be inundated but the roadway approaches were susceptible to flooding.  This finding supports other studies that have found that bridge approaches can be far more vulnerable to sea level rise than the main spans.  Even though the bridge itself may not flood, if the bridge approaches are overtopped with water, the bridge will be unusable.  For this reason, bridge approaches may need to be built or modified to higher elevations.

The study also includes a methodology for incorporating sea level rise and storm surge impacts to roadways into the HRTPO Long-Range Transportation Plan Project Prioritization Tool.  Furthermore, it contains adaptation strategies, design considerations, best practices, and lessons learned from other coastal regions (e.g. Gulf Coast) that are also vulnerable to sea level rise and storm surge.

Click Here to view a copy of the draft report.

The draft report is open for public review and comment until January 29, 2016.  All interested parties are encouraged to review the draft report and send comments to Mr. Sam Belfield at sbelfield@hrtpo.org or by mail to 723 Woodlake Drive, Chesapeake, Virginia 23320.

 

 

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