Coast and Shoreline Change Analysis Program

The Coast and Shoreline Change Analysis Program (CSCAP) is an initiative that enables personnel to analyze shoreline changes in port areas by comparing recent high resolution commercial satellite imagery with existing NOAA Electronic Navigation Charts (ENCs). By digitally overlaying the satellite imagery with the chart data, positional inaccuracies and changes in the shoreline and alongshore features (piers, jetties, etc.) can be easily detected, and the corrections and updates can be quickly compiled and submitted for rapid update of NOAA charts and ENCs.

Typically the lowest-cost basic products available from commerical high resolution imagery vendors are purchased for use in CSCAP analysis. The imagery characteristically has a very high spatial resolution (<= 1 meter), is non-orthorectified, and has a relative positional accuracy estimated from 15 meters to 23 meters circular error at the 90% confidence level (Geo Eye, Inc., 2004; Digital Globe, Inc., 2005). Using the georeferencing tools in ESRI®'s ArcGIS® software, the satellite imagery is spatially adjusted to line up visually with the ENC and change analysis is performed. Discrepancies between the imagery and ENC are recorded in a ChartEvaluation File (CEF) utilizing the openly published (nonproprietary) shapefile format developed by ESRI®.

Once CSCAP analysis has been completed, recommendations are made for resolving differences between the imagery and ENC. These may include compilation of isolated minor changes or corrections from the satellite imagery, extensive recompilation of vast portions of the commercial port area from the satellite imagery, or initiation of a full scale photogrammetric survey of the entire port. If shoreline features are compiled from the satellite imagery, preparations are made to refine the image geopositioning in oder to meet rigorous chart accuracy requirements.