U.S. Geological Survey, New England Water Science Center MA office 20150507 vector digital data SIR 2014-5236 Reston, Virginia U.S. Geological Survey http://link to location where data will be available http://pubs.usgs.gov/sir/2014-5236 US Geological Survey, New England Water Science Center 20150507 document Scientific Investigations Report 2014-5236 Reston, Virginia U.S. Geological Survey Lombard, P.J., and Bent, G.C., 2014, Flood-inundation and Recovery maps for the Hoosic River from the confluence with North Branch Hoosic River to the Vermont State Line, North Adams and Williamstown, Massachusetts: U.S. Geological Survey Scientific Investigations Report 2014-5236, 15 p. http://pubs.usgs.gov/sim/2014-5236 Digital flood-inundation maps for a eight-mile reach of the Hoosic River from the confluence with North Branch Hoosic River to the Vermont State Line, in North Adams and Williamstown, Massachusetts, were created by the U.S. Geological Survey (USGS) in cooperation with FEMA. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage at Hoosic River near Williamstown, MA (01332500). Current conditions at the USGS streamgage may be obtained on the Internet. The NWS forecasts flood hydrographs at many places that are often collocated at USGS streamgages. The forecasted peak-stage information, also available on the Internet, may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. In this study, flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated using the most current stage-discharge relations at the Hoosic River near Williamstown gage and documented high-water marks from recent floods (if available). The hydraulic model was then used to determine water-surface profiles for floods with annual exceedance probabilities of 1% and 0.2% referenced to the streamgage. The flood-peak inundation area was modeled in a GIS by combining [high-water mark data, and/or steady-state hydraulic modeling] and available [Lidar] digital elevation model (DEM) data as part of the U.S. Geological Survey study of the flood of August, 2011 in Williamstown and North Adams, MA. Information about the study, floods, and methods used can be found in the USGS Scientific Investigations Report 2014-5236. http://pubs.usgs.gov/sim/2014-5236 This dataset was created to support the development of flood-peak inundation maps for documenting the extent of the August 2011 flood along a reach of the Hoosic River in Williamstown and North Adams, MA. A GIS application was used to produce a plane representing the flood-peak water surface. The application duplicates the water-surface-elevation data from cross-section points across the flood plain perpendicular to the direction of the flood flow. Elevations between water-surface points on the cross-sections are proportional interpolations of the water-surface-elevation data and were positioned to generate a flood surface sloping with the water flow. The flood-peak inundation areas are available in a GIS format, shapefile, that provides extent of the flood peak for the annual exceedance probabilities of 1% and 0.2% (equivalent to 100-year and 500-year recurrence interval flows. This format allows the GIS data to be overlain on maps and aerial photographs, and to be used for various GIS applications, such as FEMA's Hazards U.S. Multi-Hazards (HAZUS-MH) program (Federal Emergency Management Agency, 2010b) to estimate flood damages. For more information on data processing and checking procedures, see the full report at http://pubs.usgs.gov/sim/2014-5236 Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the dataset in nonproprietary form, as well as in ArcGIS format, this metadata file may include some ArcGIS-specific terminology. 20140808 ground condition Complete None planned -74.100322 -74.066216 40.923740 40.868051 none flood river/stream flood-inundation maps high-water marks flooded area geospatial analysis none North Adams, Williamstown MA Hoosic River None. This dataset is provided by USGS as a public service. Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The flood boundaries shown were estimated based on water stages/streamflows at the USGS streamflow-gaging station Hoosic River near Williamstown, MA (01332500), steady-state hydraulic modeling (assuming unobstructed flow), and a digital elevation model. The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing in May, 2014. Unique meteorological factors (timing and distribution of storm) could cause actual streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations from the water surface elevations and inundation boundaries shown here. Additional areas may be flooded due to unanticipated backwater from major tributaries along the main stem or from localized debris- or ice-jams. Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. Although USGS intends to make this server available 24 hours a day, seven days a week, timely delivery of data and products from this server through the Internet is not guaranteed. The USGS provides these maps "as-is" for a quick reference, emergency planning tool but assumes no legal liability, or responsibility resulting from the use of this information. US Geological Survey, New England Water Science Center MA Office mailing and physical address

10 Bearfoot Rd

Northborough MA 01532 508-490-5041 Unclassified Microsoft Windows 2000 Version 5.2 (Build 3790) Service Pack 2; ESRI ArcCatalog 9.3.1.1850 Attributes for water surface elevation were input from the HEC-RAS model output data table. Peak flow input data for the HEC-RAS model is from published USGS data. http://pubs.usgs.gov/sir/2014-5236/ There are no unclosed polygons or intersections without nodes. The ArcGIS geodatabase topology tools were used to make corrections using 11 rules including no gaps, no duplicate lines with the same beginning and ending nodes.] This dataset is complete; there are no planned revisions or updates at this time. Used cross-section data points from surveyed data, accurate to the datum of the survey. Flood inundation extent was manually checked by sampling the digital elevation model (DEM) adjacent to high water marks. This check was done to verify that DEM elevations greater than the high-water mark were not in the flood inundation polygon and elevations less than the high water mark were within the flood inundation polygon. Used cross-section data points from surveyed data, accurate to the datum of the survey. Flood inundation extent was manually checked by sampling the digital elevation model (DEM) adjacent to high water marks. This check was done to verify that DEM elevations greater than the high-water mark were not in the flood inundation polygon and elevations less than the high water mark were within the flood inundation polygon.Vertical accuracy to the input Lidar DEM dataset. Pamela J. Lombard Hydraulic model Numeric hydraulic model 2014 ground condition Numeric hydraulic model was used to compute water surface profiles at selected elevations along mapped reach. The water surface profiles were then used to generate the inundation map boundaries. Metadata imported. 20110504 09170200 A GIS application was used to produce a plane representing the flood-peak water surface. The application duplicates the water-surface-elevation data from cross-section points of the hydraulic model across the flood plain perpendicular to the direction of the flood flow. Elevations between water-surface points on the cross-sections are proportional interpolations of the water-surface-elevation data and were positioned to generate a flood surface sloping with the water flow. 08072014 Vector String two 0.000000 0.000000 0.000000 0.000000 coordinate pair 0.000000 0.000000 meters D_WGS_1984 WGS_1984 6378137.000000 298.257224 North American Vertical Datum of 1988 0.003 feet Attribute values station ID 01332500 01332500 flood-peak inundation area U.S. Geological Survey FID Internal feature number. ESRI Coordinates defining the features. Each entity corresponds to an estimated flood extent area for Annual Exceedance Probabilities of 1% and 0.2% at the USGS streamgage 01332500, Hoosic River near Williamstown, MA. Lombard, P.J., and Bent, G.C., 2014, Flood-inundation and Recovery maps for the Hoosic River from the confluence with North Branch Hoosic River to the Vermont State Line, North Adams and Williamstown, Massachusetts: U.S. Geological Survey Scientific Investigations Report 2014-5236, 15 p., http://dx.doi.org/10.3133/sir/2014-5236. US Geological Survey, New England Water Science Center MA Office GIS Specialist mailing and physical address

10 Bearfoot Rd

Northborough MA 01532 (508) 490-5065 Downloadable Data Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This coverage may be redistributed if it is not edited and is properly referenced. The flood boundaries shown were estimated based on water stages/streamflows at the USGS streamflow-gaging station Hoosic River near Williamstown, MA (01332500), steady-state hydraulic modeling (assuming unobstructed flow), and a digital elevation model. The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing on May, 2014. Unique meteorological factors (timing and distribution of storm) could cause actual streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations from the water surface elevations and inundation boundaries shown here. Additional areas may be flooded due to unanticipated backwater from major tributaries along the main stem or from localized debris- or ice-jams. Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. Although USGS intends to make this server available 24 hours a day, seven days a week, timely delivery of data and products from this server through the Internet is not guaranteed. The USGS provides these maps "as-is" for a quick reference, emergency planning tool but assumes no legal liability, or responsibility resulting from the use of this information. shapefile 0.989 http://water.usgs.gov/osw/flood_inundation/ REQUIRED REQUIRED none none Data are supplied in ArcGIS shapefile format. Format compatibility is the user's responsibility. 20140808 US Geological Survey Ask USGS - Water Webserver Team mailing address

507 National Center

Reston Virginia 20192 USA 1-888-275-8747 (1-888-ASK-USGS) FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile