Thursday, September 14, 2017

AZGS STATEMAP 2017 deliverables: Delivered!

We just delivered geologic map data for four 7.5’ quadrangles to the US Geological Survey as part of our 2017 STATEMAP work – see the list below. Before releasing the map and GIS database publically, the authors will make any necessary revisions, polish the map appearance and the legend for consistency with AZGS standards. Delivery of draft maps to the USGS program managers is required at the end of each contract period; grant funding for the next STATEMAP projects depends on this.

All participating state geological surveys submit draft maps, then clean and polish them before releasing them to the public. For the AZGS, it has typically required 6 to 15 months to finalize and release the maps, as this work is done while the geologists are also working on the next mapping projects. Meanwhile, the geologists are gearing up for the next field season, which begins later this fall or early winter.

Since 1992, AZGS has participated in the U.S. Geological Survey’s STATEMAP. To date, AZGS has received ~ $4M in federal funds, matched $ for dollar by state funds, for a total of $8 M. AZGS geologists meet annually with Arizona Geologic Mapping Advisory Committee to identify high priority areas for new mapping. Our map advisory team plays a crucial role in helping select mapping that are particularly relevant to resolving challenging geologic, and often, socio-geologic problems.

This past year, our mapping focused on quadrangles in SW and SE Arizona – see the map figure. The Dragoon area was chosen because it hosts porphyry copper deposits with substantial potential economic value. The Blythe and North Trigo Peaks quadrangles contain ancient river deposits that help us understand origin and evolution of the Colorado River, and North Trigo Peaks contains diverse and complex bedrock geology that sheds new light on Mesozoic and Cenozoic tectonism in the region.

The ~½ of the Blythe quadrangle in California covers much of the late Holocene floodplain of the Colorado River. The surficial deposits there have been completely altered by agricultural and urban activity, but our collaborators with the USGS office in Flagstaff (Debra Block and Kyle House) used historical aerial photographs and early topographic maps to make a detailed geologic map of this area.

The Gila River Valley near Safford contains the young river floodplain and multiple levels of terraces recording former river levels, and many great exposures of the basin deposits that are providing insights into how the river developed. Image: Ann Youberg examining basin-fill sediments exposed along near Ft. Thomas.

2017 Geologic Mapping

· Geologic Map of the Blythe 7 ½’ quadrangle, La Paz County, AZ and Riverside County, CA. AZGS DGM-124 – Brian Gootee, Debra Block (USGS), Philip Pearthree, Kyle House (USGS)
· Geologic Map of the North Trigo Peaks 7 ½’ quadrangle, La Paz County, AZ – AZGS DGM-123 – Charles Ferguson, Philip Pearthree, Brian Gootee, Bradford Johnson
· Geologic Map of the Ft Thomas area, Graham County, AZ – ASGS DGM-126 – Ann Youberg and Joseph Cook
· Geologic Map of the Dragoon 7 ½’ quadrangle, Cochise, County, AZ – AZGS DGM-125 – Bradford Johnson, Joseph Cook, Charles Ferguson

2016 Geologic Mapping – to be released later this fall

Meanwhile, later this year we’ll release static digital versions of the geologic maps and GIS data in a number of useful formats for the following map quadrangles.

· Pima-Markham Creek – SE Arizona
· Oatman – NW Arizona
· Moon Mountain – W Arizona
· Middle Camp Mountain – W Arizona

2018 Geologic Mapping - Planning underway
We will be meeting with our Geologic Mapping Advisory Committee in the next few weeks to determine priorities for the next mapping cycle, which will begin in September 2018. The proposal for this mapping is due to the USGS in mid-November. There are many interesting and important areas yet to map in Arizona!
Contributors: M. Conway, P. Pearthree, J. Cook

Tuesday, September 05, 2017

Modeling Post-Wildfire Debris-Flow & Flooding Assessment: Coconino County, Arizona

Cover shot of AZGS Open-File Report
Over the past decade the Southwestern U.S. has seen a surge in the number and intensity of wildland fires. In Arizona, wildfire season overlaps with the annual monsoon, resulting in post-wildfire debris flows and floods that threaten life and property.

The Arizona Geological Survey just released a report identifying areas in Coconino County, Arizona, at risk from flooding and debris flows in the aftermath of a reasonable-wildfire scenario. This report was a joint research project with JE Fuller Hydrology and Geomorphology, Inc., with offices in Tucson, Tempe, Flagstaff, Arizona, and Silver City, New Mexico.

The 63-page report, ‘Post-Wildfire Debris-flow and Flooding Assessment: Coconino County, Arizona’, includes six appendices. The report and appendices are online and free to download from the AZGS Online Document Repository.

According to first author Joe Loverich, this work can propel ‘forest health initiatives forward in these at risk watersheds’. This Thursday, Ann Youberg and Joe Loverich will be presenting some of their results at the Arizona Hydrological Society’s 30th Annual Symposium in Flagstaff.

The research team conducted a county-wide reconnaissance evaluation, before focusing on two pilot-study areas: Fort Valley and the City of Williams. The report results integrate field studies, two-dimensional FLO2D pre- and post-wildfire flood modelling, and debris-flow probability, volume and runout modeling to provide risk maps and identify mitigation options and opportunities. Conversations to implement mitigation options are in progress.

Citation. Loverich, J.B., Youberg, A.M., Kellogg, M.J. and Fuller J.E., 2017, Post-Wildfire Debris-flow and Flooding Assessment: Coconino County, Arizona. Arizona Geological Survey Open-File Report (OFR-17-06), 63 p., 6 appendices.


  • Appendix A - Pilot Area Justification Memo, Kellogg, M.J., Loverich, J.B., Youberg, A.M. and Fuller J.E.
  • Appendix B - Pre- and Post-Wildfire Hydrologic Modeling, Loverich[AY1] , J.B., Kellogg, M.J. and Fuller J.E.
  • Appendix C - Pre-Wildfire Debris-Flow Risk Assessment, Youberg, A.M.
  • Appendix D - Post-Wildfire Debris-Flow Modeling, Loverich, J.B.
  • Appendix E - Post-Wildfire Debris-Flow, Youberg, A.M.
  • Appendix F - Flood and Risk Zone Maps, Loverich, J.B., Kellogg, M.J. and Fuller J.E.
Posted M.Conway 9/5/2017