Flood-Inundation Maps for the Hohokus Brook in Waldwick Borough, Ho-Ho-Kus Borough, and the Village of Ridgewood, New Jersey, 2014 By Kara M. Watson and Michal J. Niemoczynski 2015 Scientific Investigations Report 2015-5064 Abstract: Digital flood-inundation maps for a 6-mile reach of the Hohokus Brook in New Jersey from White’s Lake Dam in Waldwick Borough, through Ho-Ho-Kus Borough to Grove Street in the Village of Ridgewood were created by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection. The floodinundation 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 on the Hohokus Brook at Ho-Ho-Kus, New Jersey (station number 01391000). Stage data at this streamgage may be obtained on the Internet from the USGS National Water Information System at http://waterdata.usgs.gov/nwis/uv?site_no=01391000 or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at http://water.weather.gov/ahps2/hydrograph.php?gage=hohn4&wfo=okx. Flood profiles were simulated for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated using the most current stage-discharge relation at the Hohokus Brook at Ho-Ho-Kus, New Jersey streamgage (station number 01391000). The hydraulic model was then used to compute 12 water-surface profiles for flood stages at 0.5-foot (ft) intervals referenced to the streamgage datum and ranging from 2.5 ft, the NWS “action stage” or near bankfull, to 8.0 ft, which exceeds the stage that corresponds to the maximum recorded peak flow (7.32 ft) and is the extent of the current stage-discharge relation for the streamgage. The simulated water-surface profiles were then combined with a geographic information system 3-meter (9.84 ft) digital elevation model[derived from light detection and ranging (lidar) data] to delineate the area flooded at each water level. The availability of these maps along with information on the Internet regarding current stage from the USGS streamgage will provide emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, as well as for post-flood recovery efforts. DISCLAIMERS: This database, identified as SIR 2015-5064, has been approved for release and publication by the Director of the U.S. Geological Survey. Although this database has been subjected to rigorous review and is substantially complete, the U.S. Geological Survey reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the U.S. geological Survey nor the U.S. Government may be held liable for any damages resulting from its authorized or unauthorized use. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other System, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. 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 information product, for the most part, is in the public domain, it also contains copyrighted materials as noted in the text. Permission to reproduce copyrighted items for other than personal use must be secured from the copyright owner. Disclaimer for Flood-Inundation Maps: Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. 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. Uncertainties and Limitations for Use of Flood-Inundation Maps: Although the flood-inundation maps represent the boundaries of inundated areas with a distinct line, some uncertainty is associated with these maps. The flood boundaries shown were estimated based on water stages (water-surface elevations) and streamflows at USGS streamgage station Hohokus Brook at Ho-Ho-Kus, New Jersey (station number 01391000). Water-surface elevations along the stream reaches were estimated by steady-state hydraulic modeling, assuming unobstructed flow, and using streamflows and hydrologic conditions anticipated at the USGS streamgage(s). The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing as of September 2004. Unique meteorological factors (timing and distribution of precipitation) may cause actual streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations in the water-surface elevations and inundation boundaries shown. Additional areas may be flooded due to unanticipated conditions such as: changes in the streambed elevation or roughness, backwater into major tributaries along a main stem river, or backwater from localized debris or ice jams. The accuracy of the floodwater extent portrayed on these maps will vary with the accuracy of the digital elevation model used to simulate the land surface. Additional uncertainties and limitations pertinent to this study may be dscribed elsewhere in this report. If this series of flood-inundation maps will be used in conjunction with National Weather Service (NWS) river forecasts, the user should be aware of additional uncertainties that may be inherent or factored into NWS forecast procedures. The NWS uses forecast models to estimate the quantity and timing of water flowing through selected stream reaches in the United States. These forecast models (1) estimate the amount of runoff generated by precipitation and snowmelt, (2) simulate the movement of floodwater as it proceeds downstream, and (3) predict the flow and stage (water-surface elevation) for the stream at a given location (AHPS forecast point) throughout the forecast period (every 6 hours and 3 to 5 days out in many locations). For more information on AHPS forecasts, please see: http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf. CONTENTS OF DOWNLOADS DIRECTORY This report consists of a report manuscript and associated inundation data files and metadata. Report: pdf/sir2015-5064.pdf Datafiles for inundation layers Depth grids for use with ArcGIS show inundation extent and water depth range. The number in the name represents the map sheet number. depth_raster/hohonj_01 depth_raster/hohonj_02 depth_raster/hohonj_03 depth_raster/hohonj_04 depth_raster/hohonj_05 depth_raster/hohonj_06 depth_raster/hohonj_07 depth_raster/hohonj_08 depth_raster/hohonj_09 depth_raster/hohonj_10 depth_raster/hohonj_11 depth_raster/hohonj_12 Shapefiles show the water-surface inundation extent. These are labeled by the USGS streamgage number and the related water-surface stage level. The stage levels increase in 1-foot increments. water_surface_final/01391000_2_5.shp water_surface_final/01391000_3_0.shp water_surface_final/01391000_3_5.shp water_surface_final/01391000_4_0.shp water_surface_final/01391000_4_5.shp water_surface_final/01391000_5_0.shp water_surface_final/01391000_5_5.shp water_surface_final/01391000_6_0.shp water_surface_final/01391000_6_5.shp water_surface_final/01391000_7_0.shp water_surface_final/01391000_7_5.shp water_surface_final/01391000_8_0.shp KML/KMZ files are for use with mapping applications such as Google Earth. These files are labeled by the USGS streamgage number and the related water-surface stage level. The stage levels increase in 1-foot increments. KML/01391000_2_5.kmz KML/01391000_3_0.kmz KML/01391000_3_5.kmz KML/01391000_4_0.kmz KML/01391000_4_5.kmz KML/01391000_5_0.kmz KML/01391000_5_5.kmz KML/01391000_6_0.kmz KML/01391000_6_5.kmz KML/01391000_7_0.kmz KML/01391000_7_5.kmz KML/01391000_8_0.kmz INSTRUCTIONS AND DOCUMENTATION FOR U.S. GEOLOGICAL SURVEY SCIENTIFIC INVESTIGATIONS Report 2015-5064 To access the data: The data files can be downloaded via the web from http://dx.doi.org/10.3133/sir20155064 .The main product is a Portable Document Format (.pdf) map and pamphlet which requires Adobe Acrobat for viewing. Acrobat software runs on a variety of systems, and is available for download free of charge from Adobe at http://www.adobe.com. To access the inundation layers and depth grids, AcrGIS 10.1 is preferred, older versions may work also. To access the .kmz files in this report, download and install Google Earth at http;//www.google.com/earth/index.htm. Launch Google Earth, and click the file menu and choose open. Locate and select the .kmz file on your computer. References to non-U.S. Department of the Interior (DOI) products do not constitute an endorsement by the DOI. By viewing the Google Maps API on this Web site the user agrees to these terms(terms found at: http://code.google.com/apis/maps/terms.html) of Service set forth by Google. Software preferred: Adobe Acrobat (6.x, 7.x, or 8.x), or Adobe Acrobat Pro (6.x, 7.x, or 8.x), or the free Adobe Reader (6.x, 7.x, or 8.x), 8.x is preferred.ArcGIS 10.1 preferred, older versions may also work. ArcReader may be downloaded free of charge from http://www.esri.com/software/arcgis/arcreader/download.htm for viewing additional files included in this report.