Computer Software for Calculating Shoreline Change (or positional change of a boundary over time) The Digital Shoreline Analysis System (DSAS) is an add-in to Esri ArcGIS desktop v. 10.4-10.6 that enables a user to calculate shoreline rate-of-change statistics from multiple historical shoreline positions. It provides an automated method for establishing measurement locations, performs rate calculations, provides the statistical data necessary to assess the robustness of the rates, and includes a beta model of shoreline forecasting with the option to generate 10- and/or 20-year shoreline horizons and uncertainty bands. A user-friendly interface of simple buttons and menus guides the user through the major steps of shoreline change analysis. Components of the extension and user guide include instruction on the proper way to define a reference baseline for measurements, automated and manual generation of measurement transects and metadata based on user-specified parameters, and an explanation of the options to visualize the output of calculated rates of shoreline change and other statistical information.