Landsat assessment of estuarine water quality with specific reference to coastal land-use.




Hill, J.M.

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Texas A&M University


The highly productive and economically valuable estuaries of the United States are under environmental stress. The effects of human beings in most cases will inevitably increase turbidity, siltation and related pollution in waters in the coastal zone. It is not only aesthetically unpleasing to view waters of low clarity, but an increase in sediment load and resulting turbidity can reduce aquatic productivity, fill dams which cause flooding, and increase the transport mechanism of various pollutants. The detection and monitoring of water color spectra and, where possible, turbidity can be used to find the sources of runoff. The runoff can be used to trace current patterns, distribution of effluents, and related physico-biological relationships. Poor water quality is ultimately the result of land-use problems. Land-use changes must also be closely monitored over time in order to develop management practices that best take water quality into consideration. If Apalachicola Bay, Florida, a relatively pristine and economically valuable estuary, is to be preserved, studied, and managed successfully the relationship of land-use to water quality must be monitored. Florida State University (FSU) has been collecting water quality data, on an almost biweekly basis, since 1972. Landsat was launched in 1972, thereby creating an invaluable and almost irreplaceable data base for correlative water quality - land-use investigations. The University of Florida (UF) is attempting to create a hydrologic model of Apalachicola Bay and the East Bay drainage basin. UF is using FSU's water quality data to drive a hydraulic model of Apalachicola Bay. They, however, needed synoptic temporal distributions of water classes and land-use activities in and around the Bay which were provided through the use of Landsat in this research effort. To obtain the results of this research, Landsat-1 data were examined to determine their use in detecting and discriminating temporal distributions of water classes (colors) and land-use categories in the bay area. Water color distributions, which were associated with various water quality parameters, were easily discriminated. Water quality information, such as current distributions, the effects of man-made and natural structures (i.e., holes in barrier islands, channels, islands (bridges), and oyster bars) and distributions of various water types (i.e., acidic swamp runoff, turbid river water, clear Gulf water), were derived from Landsat data. Broad land-use categories, with a particular emphasis on silviculture, were also easily detected. The information derived from this research is being used by UF in the planning stages of their samplng program and will eventually be used to help construct and validate the resulting water quality model of the Bay System. The potential for the acquisition and use of temporal quantitative water quality and related land-use data have been demonstrated. The collection of detailed ground truth data at the same time of an overpass would make such studies a reality.


205 p., Dissertation


estuaries, water quality, satellite photography, remote sensing, water pollution, pollution, silting, turbidity, land use