Estuarine Shoreline Change: An Analysis of Hyde County, North Carolina

Abstract

Hyde County lies southeast on the flat coastal plain of North Carolina, part of the Albemarle-Pamlico Peninsula. It encompasses nationally recognized wildlife refuges and provides vital habitat for endangered, threatened, and sensitive species and natural communities. The low topography makes it extremely vulnerable to sea level rise, especially as the isostatic rates are double the global average at 0.2 - 0.4 cm per year. Climatic changes have impacted the ecosystems through rapid erosion rates. Here I measured the estuarine shoreline rate-of-change and identify priority areas, and investigated environmental predicator variables potentially explaining the erosion variability. By delineating the estuarine shorelines of 1999, 2006, and 2009 from aerial photographs in ArcMap, I was able to measure the rate-of-change for the entire study shoreline area. Three distinct areas experienced relatively higher average erosion rates, -2 m yr-1 to -3 m yr-1. Forty percent of the total shoreline length experienced moderate rates, -1 m yr-1 to -1.9 m yr-1, and 50% experienced low rates, 0 m yr-1 to -0.9 m yr-1. Classification and regression tree (CART) analysis selected directional orientation and ditch variables as influencing variables for 1999-2009 interval and 1999-2006 sub-interval. In particular, northeast and east facing shorelines with ditches exhibited the highest erosion rates. In comparison, directional orientation and percent land cultivated were selected for the 2006-2009 sub-interval. Northeast and east and southeast and south facing shorelines with associated greater than 15% cultivated land exhibited relative highest erosion rates. The CART results only explained 10% of the variance within the dataset, which suggests additional environment factors are influencing erosion rates. The most influential predictor variables varied during the latter time period, which suggests changes in landscape interactions greatly determine erosion vulnerability. Further studies should be conducted to evaluate additional environmental variables. Together, these findings and the spatial distribution of vulnerable areas allow The Nature Conservancy to prioritize shoreline areas and focus adaptation strategies to reach overall Climate Change Adaptation Project goals.