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William F Coon

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Background / Problem – The City of Ithaca, Tompkins County, N.Y., is in the process of developing a flood management plan for the streams that flow through the City. Flooding in the City is caused by a variety of distinct and sometimes interconnected reasons. Flooding often is a result of snowmelt and rain during the winter and spring. Slow ice-melt and breakup can lead to ice jams and subsequent flooding. Flash floods are produced by summer thunderstorms. All of these flood types are compounded by two factors: the storm-sewer system in the City and the elevation of Cayuga Lake. The storm sewers drain to the nearby streams at points below the tops of the streambanks. Because the streamward ends of the storm sewers...
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This dataset contains raster grids of water surface elevation for 15 modeled water-surface profiles at 5 flood frequencies (50- , 10,- 2- , 1- , and 0.2-percent annual exceedance probabilities, or 2- , 10- , 50- , 100- , and 500-year recurrence intervals) and 3 lake levels (representing average conditions, a 2-year-high condition, and a 100-year-high condition).
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Water depths were measured during November 2015 and bathymetric elevations were computed for the lower Sixmile Creek reservoir in Ithaca, Tompkins County, N.Y. These data were used to create a bathymetric surface (TIN) of the reservoir. Data collected in 1938 were used to create a second TIN and a contour line shapefile. This dataset includes the ADCP-measured transect data and manually-measured point data collected by the U.S. Geological Survey, Ithaca, N.Y., during November 16-20, 2015, and the two bathymetric-surface TINS (for 1938 and 2015) and a 1938 contour line shapefile that were created by the GIS program, City of Ithaca, N.Y.
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Digital flood-inundation maps for a 2.9-square-mile area of Ithaca, New York, were created in 2015–18 by the U.S. Geological Survey in cooperation with the City of Ithaca, New York, and the New York State Department of State. The flood-inundation maps depict estimates of the maximum areal extent and depth of flooding corresponding to selected flood frequencies for Cayuga Inlet, Sixmile Creek, Cascadilla Creek, and Fall Creek and selected water-surface elevations of Cayuga Lake. Flood profiles for the stream reaches were computed by combining a one-dimensional step-backwater model for the stream channels and a two-dimensional model for the overbank areas. The resulting hydraulic model was calibrated by using water-surface...
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Flood profiles for the stream reaches were computed by combining a one-dimensional step-backwater model for the stream channels and a two-dimensional model for the overbank areas. The resulting hydraulic model was calibrated by using water-surface profiles from five observed storm events. The model was then used to compute 15 water-surface profiles for 5 flood frequencies (50- , 10- , 2- , 1- , and 0.2-percent annual exceedance probabilities, or 2- , 10- , 50- , 100- , and 500-year recurrence intervals) and 3 lake levels (representing average conditions, a 2-year-high condition, and a 100-year-high condition). The geographic information system flood-extent polygons, depth grids, and water surface elevation grids...
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