MONITORING THE COASTAL ENVIRONMENT - PART IV - MAPPING, SHORELINE CHANGES, AND BATHYMETRIC ANALYSIS

This paper presents an overview of field methods, data collection, and analysis procedures applied to four key coastal data sets used in mon itoring and baseline studies: aerial photography, satellite imagery, p rofile surveys, and bathymetric (hydrographic) records. Often, aerial photographs and satellite images, after rectifying and georeferencing, serve as base maps to interpret landform changes and quantify shoreli ne movement. Large-scale topographic and hydrographic maps are the pri mary sources for shoreline position and volumetric change computations . Profile surveys, available from many Federal and local agencies and universities, can also be used to evaluate shoreline changes and compu te beach volume changes along and across the shore. Frequently, post-p rocessing steps are required to normalize these data to the same coord inate system and vertical datum prior to quantifying changes for a coa stal area. For example, project-specific bathymetric data in the Unite d States is often plotted using State Plane coordinates, while hydrogr aphic data from NOAA is supplied with latitude/longitude coordinates. Maps, surveys, and aerial photographs are available from Federal agenc ies such as the USGS, NOAA, and the Corps of Engineers. These long-ter m data records can be used to evaluate natural and man-made changes to a coastal system. The resultant statistics and volumetric calculation s should be presented in terms of the regional and local conditions, i .e., storm history, seasonality, wave climate, man-made environmental and engineering changes, and large-and small-scale landforms.