Shoaling characteristics of the Gulf Intracoastal Waterway in Texas.
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Maintenance dredging records were used to compute average shoaling rates in 5000-foot reaches for the entire Texas Gulf Intracoastal Waterway. Environmental data pertinent to the waterway were gathered from published and unpublished sources. Computed shoaling rates and selected environmental features were plotted on Composite Factors Maps. Similar reaches were grouped and examined using analysis of variance to determine the effect of selected environmental factors on shoaling rates. A model was also developed to predict shoaling rate in a reach with known environmental factors. The average shoaling rate over the entire waterway was found to be 10.5 inches per year. Shoaling in open bay areas was found to be an average of 3 inches per year greater than in land-cut areas. The combination of dredged material mounds, or fetch greater than 5 miles, with water depths less than 6 feet (surrounding bay depth) increased average shoaling rates 5 inches per year. The placement of dredged material in mounds on the windward side of the waterway increased the average shoaling rate of open bay areas by 7 inches per year. In bay areas with long fetches and depths less than three feet, it was found that windward placement of dredged material was actually advantageous. Hurricanes did not appear to have a drastic impact on shoaling rates; however, localized effects were noted in several areas.