Environmental Products
AAI's QSC water quality application is also used to retrieve the pixel spectrum of shallow-water bottom materials. The water composition, clarity, and depth information retrieved for each pixel is used by QSC to accurately compensate for the attenuation characteristics of the water column, and retrieve the spectrum of the bottom material in shallow waters. It can do this at sub-pixel scales, allowing the spectra of individual component materials in "mixed" pixels to be retrieved. The substrate materials are characterized for each pixel in terms of their spectral reflectance characteristics, which can be used to classify and identify them at subpixel scale (for mixed material classification). The component spectra are sensitive indicators of bottom type and condition, allowing the status of submerged ecosystems to be assessed. The retrieved depth information provides companion morphological characterization. The bottom "maps" provide valuable reconnaissance and assessment utility. These broad-area "maps" of substrate material classes, for example, provide an important contextual view of the status of the water body overall and at particular sites of interest. This permits meaningful contextual assessments of substrate conditions, such as sedimentation characteristics, diversity, invasives, die-back, morphological changes, bank erosion, etc. Retrieved depths provide key planiform and profile characteristics of the water body, as well as the characteristics of known or unexpected morphological features, such as shoals and other navigational hazards. Access to historical archived imagery allows the establishment of specific quantitative restoration targets, which can be benchmarked to supportable conditions that characterized an earlier specified year. The retrieval of specific quantitative information from sequentially acquired imagery makes possible quantitative assessments of progress against restoration targets.
Substrate material mapping near Fort Lauderdale, FL (above) reveals variations in coral reef health. Green areas are healthier with more diversity. The companion depth map (below) provides valuable bottom morphology characteristics of the hard sand and reef substrates. NOAA soundings data are shown in the depth map for comparison. The small circles are color coded according to the same key used for the image-derived depths. Comparison of the colors in the circles to the surrounding color provides an indication of the level of agreement between the image-derived and ship-based acoustic depths. Each pixel has an independently derived depth, color-coded according to the key on the left. NOAA soundings data are shown for comparison. The soundings depth is indicated by both the number (meters) and the color in the circle, which uses the same color key on the left. Note the good agreement with the soundings data, and finer-scale spatial detail provided by the image data.
The substrate material for a second zoomed-in area near Fort Lauderdale, FL is shown below (left). An adaptive spectral enhancement capability within QSC was applied to reveal further bottom sand detail (right). The patterns reveal complex bottom structure and materials in the sandy area.
Image-retrieved depths from a QuickBird image of an area near Trinidad, CA are shown (above) on the left, color-coded according to the key. Acoustic-derived depths are shown (above) on the right for comparison (data from the California Mapping Project, provided courtesy of Fugro Earth Data, Inc). The image-derived bottom morphology more fully defines shallow water navigation hazards than the available acoustic data (above right). Coverage provided by the image-retrieved depths extends into the shallower near-shore area, where acoustic (too hazardous) and lidar (too shallow) data could not successfully be obtained. Colors of the acoustic data (above right) grade from white (less than 1 meter) through red (hazardous,1-2 meters), orange, green, cyan, and blue (deep). Agreement of the image-derived and acoustic bottom morphology are shown below, where the image-derived depths were converted to a digital elevation map projection, and the acoustic data were draped over it.
Image-derived substrate materials for an area around Trinidad Rock, CA are shown below (left). The area shown as rocky (blue) in the northern part of the figure overlaps the area in the previous figure showing the image-derived and acoustic-derived depths. The raw QuickBird image is shown on the right for comparison.
Red = Seaweed / Kelp
Light Green = Loose Sand
Dark Green = Firm Sand / Mud / Rocks
Blue = Rocks
The patterns of substrate material characteristics (below) in an area near Airedele, East of St Mary's City along the Chesapeake Bay (see location above) reveal a high level of complexity.
The complex substrate characteristics near Blunts Cove, Patuxent River, MD (above) reveal a submerged habitat area threatened by silt deposition (red).
An image-derived substrate map of eelgrass beds near Pamet Harbor, Cape Cod, MA reveals deteriorating conditions of this critical habitat, particularly in the beds south of the harbor entrance. Eelgrass appears in shades of green, while sediments are in shades of brown to light tan.
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