An integrated approach to flood hazard assessment on alluvial fans using numerical modeling, field mapping, and remote sensing

Abstract

Research Article| September 01, 2005 An integrated approach to flood hazard assessment on alluvial fans using numerical modeling, field mapping, and remote sensing Jon D. Pelletier; Jon D. Pelletier 1Department of Geosciences, University of Arizona, 1040 E. Fourth Street, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Larry Mayer; Larry Mayer 1Department of Geosciences, University of Arizona, 1040 E. Fourth Street, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Philip A. Pearthree; Philip A. Pearthree 2Arizona Geological Survey, 416 W. Congress Street, Suite 100, Tucson, Arizona 85701, USA Search for other works by this author on: GSW Google Scholar P. Kyle House; P. Kyle House 3Nevada Bureau of Mines and Geology, Mail Stop 178, University of Nevada, Reno, Nevada 89557, USA Search for other works by this author on: GSW Google Scholar Karen A. Demsey; Karen A. Demsey 43055 NE Everett Street, Portland, Oregon 97232, USA Search for other works by this author on: GSW Google Scholar Jeanne E. Klawon; Jeanne E. Klawon 5U.S. Bureau of Reclamation, P.O. Box 25007, Denver, Colorado 80225, USA Search for other works by this author on: GSW Google Scholar Kirk R. Vincent Kirk R. Vincent 6U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Jon D. Pelletier 1Department of Geosciences, University of Arizona, 1040 E. Fourth Street, Tucson, Arizona 85721, USA Larry Mayer 1Department of Geosciences, University of Arizona, 1040 E. Fourth Street, Tucson, Arizona 85721, USA Philip A. Pearthree 2Arizona Geological Survey, 416 W. Congress Street, Suite 100, Tucson, Arizona 85701, USA P. Kyle House 3Nevada Bureau of Mines and Geology, Mail Stop 178, University of Nevada, Reno, Nevada 89557, USA Karen A. Demsey 43055 NE Everett Street, Portland, Oregon 97232, USA Jeanne E. Klawon 5U.S. Bureau of Reclamation, P.O. Box 25007, Denver, Colorado 80225, USA Kirk R. Vincent 6U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303, USA Publisher: Geological Society of America Received: 14 Dec 2003 Revision Received: 16 Nov 2004 Accepted: 03 Jan 2005 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2005) 117 (9-10): 1167–1180. https://doi.org/10.1130/B25544.1 Article history Received: 14 Dec 2003 Revision Received: 16 Nov 2004 Accepted: 03 Jan 2005 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jon D. Pelletier, Larry Mayer, Philip A. Pearthree, P. Kyle House, Karen A. Demsey, Jeanne E. Klawon, Kirk R. Vincent; An integrated approach to flood hazard assessment on alluvial fans using numerical modeling, field mapping, and remote sensing. GSA Bulletin 2005;; 117 (9-10): 1167–1180. doi: https://doi.org/10.1130/B25544.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Millions of people in the western United States live near the dynamic, distributary channel networks of alluvial fans where flood behavior is complex and poorly constrained. Here we test a new comprehensive approach to alluvial-fan flood hazard assessment that uses four complementary methods: two-dimensional raster-based hydraulic modeling, satellite-image change detection, field-based mapping of recent flood inundation, and surficial geologic mapping. Each of these methods provides spatial detail lacking in the standard method and each provides critical information for a comprehensive assessment.Our numerical model simultaneously solves the continuity equation and Manning's equation (Chow, 1959) using an implicit numerical method. It provides a robust numerical tool for predicting flood flows using the large, high-resolution Digital Elevation Models (DEMs) necessary to resolve the numerous small channels on the typical alluvial fan. Inundation extents and flow depths of historic floods can be reconstructed with the numerical model and validated against field- and satellite-based flood maps. A probabilistic flood hazard map can also be constructed by modeling multiple flood events with a range of specified discharges. This map can be used in conjunction with a surficial geologic map to further refine floodplain delineation on fans.To test the accuracy of the numerical model, we compared model predictions of flood inundation and flow depths against field- and satellite-based flood maps for two recent extreme events on the southern Tortolita and Harquahala piedmonts in Arizona. Model predictions match the field- and satellite-based maps closely. Probabilistic flood hazard maps based on the 10 yr, 100 yr, and maximum floods were also constructed for the study areas using stream gage records and paleoflood deposits. The resulting maps predict spatially complex flood hazards that strongly reflect small-scale topography and are consistent with surficial geology. In contrast, FEMA Flood Insurance Rate Maps (FIRMs) based on the FAN model predict uniformly high flood risk across the study areas without regard for small-scale topography and surficial geology. 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