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Jurisdictional wetland delineation in the Texas Gulf Coast Prairie utilizing aerial photography
Abstract
The intent of this study was to analyze the accuracy of jurisdictional delineations which were conducted using readily available aerial photographs of different scales and film type, taken after differing rainfall events. Boundaries of wetlands were recorded and all area calculations were determined with the use of a Geographic Information System (GIS). Fourteen aerial photographs taken at different scales, time periods, and in either black and white (B&W) or color infrared (CIR) film type were used to delineate jurisdictional wetlands within randomly selected grids for two study sites within the Gulf Coast Prairie Region of Texas. The wetland delineations for each photograph were compared to onsite delineations recorded with a global positioning system instrument and entered into a GIS. Onsite delineations were performed using a standard technique for wetland delineations based on the 1987 Corps of Engineers Wetland Delineation Manual. Area calculations were obtained for the remotely sensed wetlands, the,jurisdictional wetlands, areas of inclusion (wetlands which occurred within the remote sensing and the onsite method), omission (wetlands omitted by the remote sensing method), and commission (upland areas delineated as wetlands by the remote sensing method). An equation named ACUWET was used to discount areas of inclusion, by omission and by commission, as they related to the total area of jurisdictional wetlands within a grid cell. The rainfall amounts received one month prior to the date of each photograph showed a significant correlation to the accuracy calculations of inclusion and ACUWET. Rainfall, along with the quality of photography, proved to be the most critical factor influencing the accuracy of jurisdictional wetland delineations performed. There were no significant differences found between the effectiveness of CIR and B&W photos of the same quality. Delineations from photo scales of 1:24,000 were not more accurate than those from 1:40,000. Delineations performed on 1995 CIR photographs at a scale of 1:40,000, were the most accurate of photos tested. These 1995 CIR photographs, at a scale of 1:40,000, are readily available for much of the coastal area of east Texas.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references: p. 44-46.
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Citation
Watson, Samuel Jewell (1997). Jurisdictional wetland delineation in the Texas Gulf Coast Prairie utilizing aerial photography. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -W18.
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