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Floods

1921 snow melt at camera station near Courthouse Wash
1921 snow melt at camera station near Courthouse Wash

FLOODS IN GRAND COUNTY, MOAB CITY & COLORADO RIVER BASIN

Visit: On The Colorado for a more detailed list of flood related publications.

UMTRA STEERING COMMITTEE MEETING (January 24, 2017)

DOCUMENTS

WEBSITES

GRAPHICS

BRIEF ANALYSIS:
PALEOFLOOD RECORD OF COLORADO RIVER ABOVE MOAB

2014 - 2000 Year Record of Magnitude and Frequencies of Largest Upper Colorado River Floods at Moab, Utah. Greenbaum et al.

The purpose of the study, performed by University of Arizona (Tucson) under the direction of Victor Baker, John Dohrenwend and Noam Greenbaum, was to provide rigorous data to stakeholders and decision-makers to help ensure the removal of Moab’s uranium waste pile from the floodplain of the Colorado River, which is indeed happening. So far, 50% of the pile has been removed and taken by railroad to a burial site 30 miles north of town at a location called Crescent Junction adjacent to the I-70 corridor. The funding for this paleoflood project was provided by The Citizens' Monitoring and Technical Assistance Fund.

After the report was published, paleoflood research has continued in the upper basin of the Colorado River. For example, in 2010, sites along the Dolores River were located and sampled. In 2010 and 2012, sites were located and sampled in Stillwater Canyon on the lower Green River, and in Cataract Canyon below the confluence of the Green and Colorado rivers. Work in the near future will occur in Grand Canyon.

Highlights of this report include:

  • River section: Upper Colorado River (above the Green River confluence and below the Dolores River, the last major tributary)
  • Site location: 10.5 miles above the Moab Bridge
  • Time frame: The last 2,140 years (+/- 220 years)
  • Number of floods: 44
  • Range of floods in cfs: 60,036 to 349,616
  • 34 - 40 floods: exceeded the magnitude of the USGS 100-year flood determination
  • 20 - 25 floods: exceeded the magnitude of the USGS 500-year flood determination
  • 5 floods: exceeded a peak discharge of 282,000 cfs
  • Largest floods: two were slightly over 349,000 cfs
  • 100-year flood: peak discharge ranging from 156,440 to 179,050 cfs
  • 500-year flood: peak discharge ranging from 224,780 to 265,570 cfs
  • 1000-year flood: peak discharge ranging from 256,740 to 310,770 cfs

ADDITIONAL INFORMATION