Aerial Photography and Shoreline Mapping
- A Bird's Eye View. What better way to monitor the approximately 95,000 miles of U.S. coastline than from a bird’s eye view? Since the early 1900s, the National Geodetic Survey has been doing that—taking photographs from airplanes to capture the Earth below. Today, the capture of these aerial photographs is controlled by Global Positioning System techniques and the photos are used to define the national shoreline, create maps and charts, and monitor environmental change.
- Aerial Photos: The Basics. Aerial photographs are a little different than the photos you might take with your own camera. The primary aerial photographic product is a 9x9-inch color photograph, usually at scales from 1:10,000 to 1:50,000. Other types of photographs include panchromatic, false-color infrared, and black-and-white infrared. The National Geodetic Survey is transitioning from film-based aerial photography to digital aerial photography. More than 500,000 photo negatives, dating from 1945 to the present year, exist in NOS archives and are maintained by the National Geodetic Survey. Surveys are conducted on varying time cycles, depending on the amount of change caused by human or natural forces. Photography is acquired when weather conditions, the sun angle, and water levels are optimal to capture the right shot.
- A Basis for Nautical Charts. Aerial photographs are the primary source material used to create coastal survey maps. These data sets, in turn, provide information for producing NOAA nautical charts. Combining information from aerial photographs with hydrographic data helps to ensure that nautical charts are accurate. Nautical charts are one of the most fundamental tools available to mariners for planning voyages and navigating ships using the shortest, safest, and most economical routes. Therefore, it is especially important that the information displayed on charts is correct.
- Boundary Definitions. Ever wonder who marks where one property line stops and another starts? What about when that boundary is in the water? The shoreline—where water and land meet—is commonly referenced as a boundary component in legal descriptions, as the point of origin for jurisdictional boundaries, and as the boundary between public and private ownership. One of the tools used to define the boundaries between private, state, and federal ownership and jurisdictions, including the territorial sea and the Exclusive Economic Zone, is aerial photography.
- Coastal Change Assessment. Changes in the shape of the shoreline can be analyzed by measuring differences in past and present shoreline locations. Comparison of ‘before’ and ‘after’ aerial photographs is one way that scientists determine shoreline change. By looking at data over a period of time, scientists can even determine how fast the coast is changing, which can help with planning for the future.
- Disaster Response. Just hours after a hurricane hits a coastal area, the National Geodetic Survey begins flying photo survey missions to assess storm damage. The digital photos often are made available over the internet within 12 hours after the survey mission. The data contained in these photos provide emergency and coastal managers with information needed to develop recovery strategies, facilitate search and rescue efforts, identify hazards to navigation and HAZMAT spills, locate errant vessels, and provide documentation necessary for damage assessment through the comparison of before and after imagery.
- Benthic Mapping. Scientists use the term ‘benthic’ to refer to anything associated with or occurring on the bottom of a body of water. Understanding benthic habitats is necessary for development and implementation of a wide variety of resource management policies. Benthic habitats are mapped and studied using a variety of tools and techniques. Aerial photography is one such tool. Scientists use aerial photographs to identify different habitats along the shore and in shallow water.
- Elevation Mapping. Knowing the elevation of a coastal area is important for conservation, development, planning, and safety. The NOAA Coastal Services Center collects high-resolution elevation data using Light Detection and Ranging (LIDAR) and Interferometric Synthetic Aperture Radar (IfSAR or InSAR) technologies. Coastal elevation maps provide important information for coastal communities, as in coastal areas a change in elevation of one foot can make huge differences in habitats and human safety.
Original article: Aerial Photography and Shoreline Mapping