A Geospatial Framework for the Coastal Zone National Needs for Coastal Mapping and Charting (2004) / Chapter Skim
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4 Improving the Quantity and Quality of Coastal Reference Frame Data
4 Improving the Quantity and Quality of Coastal Reference Frame Data
Pages 74-84
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From page 74... ...
In 1999 the Coastal Services Center (CSC) surveyed 270 offices representing state resource and environmental protection agencies, coastal zone management programs, Sea Grant programs, National Estuarine Research Reserves, National Estuary Programs, and National Marine Sanctuaries (CSC, 1999)
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From page 75... ...
. Nearly half the depths published on current charts were measured using lead line techniques over a sparse grid prior to 1940, and one-third of the national shoreline has yet to be mapped.
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From page 76... ...
and NOAA datasets function essentially as national cartographic industry standards and, with tens of millions of users, are the two most widely used map/ chart series available in the United States, it is clear that it is not possible to create a single, seamless database combining the two without considerable effort. One very important reason for this is that the surface area between Mean Lower Low Water (MLLW)
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From page 77... ...
The most comprehensive modern bathymetric data being collected in shallow water are currently acquired with multibeam sonar from a survey launch. Standard multibeam sonar acoustic techniques for collecting high-resolution bathymetric data map a swath of seafloor over a fixed angle (typically 120° to 150° or 3.4 to 7.4 times the water depth)
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From page 78... ...
While current bathymetric LIDAR systems do not achieve the same data density or level of resolution as multibeam acoustic systems in similar water depths, they can rapidly provide a relatively complete and accurate picture of seafloor bathymetry. They can record data in up to 50 to 60 meters of water where water clarity permits, with a swath width that is unchanged by water depth (typically about 200 meters)
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From page 79... ...
AUV-Deployed Sonars An alternative to launches in turbid waters where bathymetric LIDAR is impossible is the use of AUV technology as the platform for sonar and imagery sensors. With the right type of AUVs, enhanced endurance and the ability to operate in a higher sea state can dramatically improve the productive survey time.
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From page 80... ...
These new systems will simultaneously collect data from airborne bathymetric LIDAR, airborne topographic LIDAR, digital imaging systems, and perhaps even a hyperspectral scanner. All systems will be navigated using the same satellite-based system to provide a common vertical and horizontal reference frame.
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From page 81... ...
Again, with a national structure that allows coordination of efforts, it should be possible to maximize LIDAR coverage. Innovative Surf Zone Vehicles Difficulties in using acoustic and other remote sensing technologies in very turbid water and in the surf zone have led investigators to develop a variety of bottom-following devices that are tracked by instruments to provide instantaneous measurements of bottom elevation.
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From page 82... ...
With the advent of total surveying stations, all that is needed is a reflecting prism mounted on the top of the mast to obtain its spatial coordinates. Self-propelled vehicles to eliminate the need for towing were developed in the 1970s (Birkemeier and Mason, 1984)
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From page 83... ...
Commercial mariners routinely provide weather observations and, through NOAA's Voluntary Observing Ship Program, commercial ships are equipped to take bathythermograph observations. The members of the International Seakeepers Society equip their yachts with sophisticated observation modules capable of measuring several meteorological and near-surface water column parameters.
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From page 84... ...
If ground control is used, IKONOS images are capable of producing mapping products with meter position accuracy for general land features and submeter accuracy for objects that can be measured at subpixel level (Di et al., 2003)
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