Assessing Treefall Patterns and Causal Relations of Wind and Surge from Hurricane Sandy

Science Center Objects

As tropical storms and hurricanes move onshore and make landfall, wind and storm surge can be sufficiently high to damage built-infrastructure and natural systems, most notably coastal forests at the interface of land and sea.

Intensive ground surveys and line transects were established across the marsh/forest ecotones
Intensive ground surveys and line transects were established across the marsh/forest ecotones.

The Science Issue and Relevance: As tropical storms and hurricanes move onshore and make landfall, wind and storm surge can be sufficiently high to damage built-infrastructure and natural systems, most notably coastal forests at the interface of land and sea. Hurricane Sandy was an expansive climate system earning the description of “superstorm” though not of major hurricane status reaching only Category I peak winds. Tracking parallel to the East Coast prior to coming ashore in New Jersey, Sandy inflicted measurable damage from Florida to Maine given its super-size and high storm tides. Determining the contribution of wind and surge as causal factors for downed and dead trees is important to relating storm characteristics and ecosystem vulnerability and success for forest recovery or reforestation. Park and refuge managers need information on the degree to which forest cover at the coastal interface is critical to maximizing storm protection and minimizing impact to upslope built-infrastructure guiding decisions about ecosystem recovery, research and restoration.

Methodology for Addressing the Issue: Ground and aerial surveys were conducted to catalog the expression and extent of forest damage of coastal parks and refuges along the East Coast following Hurricane Sandy. Phone interviews and site visits to 30+ DOI land management units were conducted to document the range and severity of damage to coastal forest habitat from Florida to Maine. Intensive ground surveys and line transects were established across the marsh/forest ecotone involving tree core collections of surviving trees, compass directions of downed trees, soil sediment cores, and interstitial porewater samples for determining soil salinities. Observed treefall directions were shown to be non-random and associated with hurricane tracking and approach corresponding in most cases to simulated forewind azimuths. 

Future Steps: The project will produce an understanding of the interaction of storm surge tides on soil liquefaction and wind force and direction that can be applied in explicit landscape simulation models to improve predictive modeling of future ecosystem consequences under climate change and increasing hurricane frequency and intensity.

Azimuth frequencies for 5-degree bins, at Forsythe
Azimuth frequencies for 5-degree bins, at Forsythe
Azimuth Frequencies for 5-degree bins, at Chincoteague
Azimuth Frequencies for 5-degree bins, at Chincoteague