Geomorphic analysis of United States East Coast shoreline behavior and the influence of tidal inlets on coastal configuration

apping historical shoreline positions is a standard technique to determine rates of beach erosion. However, the spatial and temporal variability of shoreline change is often misunderstood, and often times short-term (;Tidal inlets are the most important features along sandy coastlines in terms of littoral processes. Inlet dynamics have a significant impact on the configuration of adjacent beaches and cause significant changes in beach planform for many kilometers. A number of studies have attempted to establish the spatial extent of inlet influence on adjacent shorelines. Results to date varied and tend to treat the arc of erosion as a static feature, typically relying on short-term data.;This research quantifies the long-term shoreline behavior of open-ocean beaches from Long Island, New York to South Carolina using shoreline change analysis to answer three important questions: (1) What is the long-term behavior of mid-Atlantic beaches in terms of erosion, accretion, and stability; (2) What is the minimum period of record required for accurate shoreline change analysis; and (3) What is the temporal and spatial extent of the inlet-induced modifications to adjacent shorelines?;Erosion is a pervasive process and 86% of mid-Atlantic beaches are undergoing long-term erosion. Plots of endpoint shoreline change rates were used to determine the temporal variability of shoreline position and indicate that at least 100 years of data are required to make an accurate estimate of the trend. The scatter in endpoint rates is so large at time scales less than 80 years that an arbitrary endpoint trend is as likely to be erosional as accretional. Hence, the use of the end point rate method to determine shoreline change rates can lead to extremely large errors and is not recommended. Linear regression usually leads to smaller errors in trend estimation. The best estimates of shoreline change rates come from analyses that consider the effect of the erosion and beach recovery associated with large storms, in addition to any anthropogenic or natural alterations of shoreline configuration. The data show that after large storms the beach takes many years to recover, and the beach recovers to a position predicted by the background trend.;Tidal inlets dominate shoreline trends and control shoreline behavior along 65% of the beaches in the study area. Outside of the influence of tidal inlets, shoreline change is unremarkable and rates-of-change seldom exceed...