Mamala Bay, offshore of Honolulu, Hawaii, has been a disposal area for dredged materials from nearby Pearl and Honolulu Harbors for over a century. The U.S. Geological Survey, the U.S. Army Corps of Engineers, and the Environmental Protection Agency are studying the dredged materials and their impact on the marine environment. Data collection includes geophysical profiling and imaging, bottom video and still photography, sampling, chemical and physical properties of sediment, and evaluation of the nature of and impact on the benthic fauna. Synthesis of this information begins with the establishment of a geographic framework for the data. Ship-based oceanographic surveys typically have several data-collection systems operating: navigation, bathymetry, camera, seismic-reflection, sidescan sonar, and sampling. All data gathered during the survey are geographically located by referencing their time of collection with the time of a navigation "fix" from satellites (GPS) and/or transponders. Time is also used to annotate interpreted data after the field activity is completed, e.g., geologic structure from seismic-reflection profiles or sidescan sonar images, or seafloor features from photographs. With time as the measure, routes and related events are used to extract and analyze data along segments of tracklines (line events) or at discrete points (point events). In addition to enabling time as the primary measure, route treatment of tracklines preserves the start-to-end continuity that is ordinarily fragmented by building arc topology. Depending on the data set, the event tables may be converted to standard line and point coverages. Oriented bottom photographs that are time-referenced are one product of this study. Bottom current direction and bottom roughness were determined from the appearance of the sediment in each photograph. A plot of the inferred current directions as a function of time along the camera tracks reveals a complex pattern with a dominant northwest-trending swath through the area. Sediment textures determined from the photographs and grain-size analyses provide confirmation along survey tracks of the textures interpreted from the sidescan sonar image that has been compiled for the area. Correlation of observed sediment textures with image data paves the way for construction of a sediment map of the whole area, both along- and between-track.
The Naval Oceanographic Office (NAVOCEANO) provides environmental data bases and derived products to the operational Navy. Various groups within NAVOCEANO use the same data sets for their specific applications, as a results, many of the tools for editing, display and data basing are similar. In an effort to standardize tools and techniques the Comprehensive environmental Assessment System (CEAS) has been developed. CEAS is a GIS software development and data integration effort providing a set of tools for geophysical, bathymetric, oceanographic, acoustic, imagery, and geopotential data assessment and product generation for NAVOCEANO's in-house users and their customers. ArcInfo is the core of CEAS providing the co-registered data sets along with the menu and window environment for accessing other tools including Geographical Resource Analysis Support System (GRASS), PV-Wave, and in-house custom software. This application uses the environmental data holdings of NAVOCEANO and other Government activities. Standard GIS functions are provided, along with robust data import/export to and from standard ArcInfo coverages and customized utilities. Data types include points, polygons, grids, imagery, and vectors. Integrated applications include range-dependent acoustic transmission loss modeling support, cable laying support, bathymetric survey design, oceanographic parameter display (e.g. sound speed, temperature and salinity), and global ocean current climatology. Unique functions include cross sectional graphs of sediment layers, great circle and terrain-following distance measurements, cable payout parameter calculations, swath bathymetry coverage calculations, transmission loss radial displays, acoustic modeling interface, 3D and animated visualization displays, grid-based modeling, cartographic quality charts, and spatial and temporal data base queries. The functionalities listed above were successfully integrated. Current development includes the migration to Oracle relational data bases, the integration to NAVOCEANO's Integrated Data Base Management System (IDBMS), and expanded capabilities. Presented are the design philosophy, physical and logical design, and results. 1 Naval Oceanographic Office, Stennis Space Center, MS 39522 2 Lockheed Martin Company, Stennis Space Center, MS 39529
Geographic information systems have become established tools for analyzing species distributions in relation to environmental variables on land. This study utilizes a GIS to investigate the influence of terrestrial and submarine topography on the near-shore marine light regime, and the distribution of giant kelp (Macrocystis pyrifera), around an island off the southern California coast. Macrocystis is an important algal species along temperate coasts, serving both as structural habitat and food for many marine invertebrates and fishes. Santa Catalina Island's NW-to-SE orientation and highly dissected, 87-km leeward and windward coastline offers a wide range of microhabitats with respect to the nearshore light regime and factors such as exposure to winter storms and temperature. GIS data layers included kelp distribution maps from several survey years, a digital terrain model, digital bathymetric model, submarine slope, submarine aspect and bottom relief. The topographic and bathymetric data layers were exported to Image Processing Workbench (IPW) to generate a series of integrated solar insolation models (monthly, seasonal, annual). An ocean surface insolation model incorporated the diurnal path of the sun, and the effect of hillshading on nearshore waters due to the adjacent island topography. Insolation on the sea floor added the elements of light extinction through the water column utilizing the bathymetric data and estimated regional turbidity. Kelp bed distribution was evaluated statistically relative to surface and bottom insolation levels. Definite patterns in distribution were observed relative to surface and bottom insolation, especially pronounced during the peak growing season. As expected, submarine aspect, depth, slope, and bottom relief also played roles in influencing local light regimes. On the leeward side, shaded from mid-day and afternoon sun by the island's 450-640 meter main ridge, kelp favored the higher light environments around coastal features such as points and offshore reefs, or regions with greater bottom relief. Kelp on the more exposed, windward side of the island favored locations sheltered from the prevailing winter storms despite lower light levels in these sites.
Traditional methods of managing oceanographic survey data have required time and labor intensive practices involving file-based manipulation of large quantities of raw data sets. Thus, the visualization and analysis of these data have traditionally been reserved for land-based laboratory environments. Recent application of geographic information system (GIS) technology to shipboard survey processes is making it possible for scientists to view and manipulate both raw and processed bathymetry, hydrography, and other geophysical data in a near-real time survey mode. An ongoing example of this level of GIS support can be found in the Oceanographic Remote Controlled Automaton, (ORCA) research program at the U.S. Naval Research Laboratory (NRL) at Stennis Space Center, Mississippi. This diesel powered semi-submersible vessel was developed to perform bathymetric surveys of the littoral ocean regions. Its ability to run in either independent or coincidental mode to other survey vessels gives the U.S. Navy an increased ability to survey shallow to medium depth water areas which make up most littoral zones. NRL is currently developing a GIS-based shipboard data viewing capability for the ORCA. The system utilizes the Environmental Systems Research Institute's ArcView and ArcInfo GIS software to offer scientists and survey support teams the ability to view and evaluate survey operations while in an in-situ mode to determine the acceptability of same-day data collection efforts. The ORCA utilizes a SIMRAD EM-950 sonar system operating in a 95-kHz multibeam configuration. February 1995 sea trials off the coast of Pensacola, FL provided ORCA bathymetry data which could be correlated to previously collected National Oceanic and Atmospheric Administration (NOAA) bathymetric data surveys of the same region. NRL's Mapping, Charting and Geodesy (MC and G) Branch has been tasked with supporting the near real-time visualization of this and subsequent ORCA data sets through the use of GIS technology. Subsequently, NRL has developed ArcView and ARC-based software tools which allow for the gridding, contouring and cartographic output of the ORCA multi-beam data sets. ARC options for creating 3D triangulated irregular networks of the bathymetry are also being utilized to drape ORCA imagery to produce enhanced 3D perspective cartographic products. This paper examines GIS processes and techniques utilized to manage, analyze, and display the ORCA data in a near real-time mode. Discussions also concern techniques used to compare ORCA data with other data collected by NOAA's WHITING and the USNS PATHFINDER on previous survey operations. Since the SIMRAD multibeam data can be readily utilized to produce multi-channel image data, discussions also include the coupling of other image processing techniques within the GIS environment to provide a full range of support to visualizing and analyzing the ORCA survey data.