THE SHORELINE WAS WHERE? INTEGRATING HISTORICAL IMAGERY AND GEOLOCATION CAPABILITIES TO IMPROVE UNDERSTANDING OF DYNAMIC BEACHFRONT GEOMORPHOLOGY AT BOTANY BAY PLANTATION HERITAGE PRESERVE, S.C

Many of the beachfront and estuarine shorelines along South Carolina's central mixed-energy barrier island coast are currently experiencing erosion and consequent shoreline retreat or transgression. State-wide, approximately 42% of South Carolina’s coastline is experiencing a very high (< -2.0 m/yr) rate of erosion (DHEC-OCRM, 2016). At several locations, this erosional trend is happening at a notably high rate. The beachfront at Botany Bay Plantation Heritage Preserve, a state-managed property that hosts upwards of 70,000 visitors annually, retreated at an average rate of -7.5 m/yr between 1949 and 2016. Between October 2015 and October 2017, the area has experienced three large storm and flooding events resulting from the impacts of Hurricanes Joaquin, Matthew, and Irma. The short-term linear rate of erosion on the beach over this time period has increased to as much as -23.0 m/yr.

Given the rapid pace of shoreline change, visitors to the property often have a host of questions for volunteer interpreters relating to the unique geologic and geomorphic features of this transgressive barrier island. To better assist volunteers at the site with explaining the extent of shoreline retreat over the past 70 years, an ESRI-based mobile-friendly Story Map has been created to overlay aerial imagery and a user’s geolocation, helping visitors better conceptualize the full extent of the change. Historical imagery available from 1949, 1973, 1989, 1994, 2002, 2013, and 2015 has been included along with a high-resolution orthoimage collected using a UAV in 2019. With this application, visitors to the site can place their current-day location in the context of the prior geomorphological configuration of the island and better understand the full extent of shoreline change over the past 70 years.