COLORADO RIVER FLOODS & CLOUDBURST HAZARDS
Discussion about the "100-Year Flood"

• Read: US Geological Survey Discussion
• Defining a 100-year flood is related to general acceptable policies for government agencies and insurance providers. This is a statistical analysis, which is obviously acceptable to governing agencies, as long as it is also understood that this standard is the minimalist approach. See: Initial-Phase Investigation of Multi-Dimensional Streamflow Simulations in the Colorado River, Moab Valley, Grand County, Utah, 2004. Kenney, USGS.
• An empirical study is letting Nature speak for itself. Nature is random, unpredictable, and extreme. For example, the 20th century was the wettest century in the last 2000-years, according to calibrated tree-ring data. Yet, the Colorado River in the 20th century did not have a single 100-year flood event, whether statistical or empirical.
• Whereas the 19th century had many serious flood events related to an atmospheric river event and volcanic eruptions in the South Pacific.
• Paleoflood hydrology is the science that provides empirical data about the frequency and magnitude of prehistoric flood events.
• Science Moab Interview with Professor Vic Baker (listen).
• Identifying flood indicators in nature: Historical and Paleoflood Analyses for Probabilistic Flood-Hazard Assessments: Approaches and Review Guidelines. Harden.
• This data in real time was recently calibrated for the Colorado River Basin above the confluence with the Green River, and as follows:

• A 100-year flood would have a peak discharge ranging from 156,440 to 179,050 cfs. Thirty-four such floods have happened in the last 2,000 years.

• A 500-year flood would have a peak discharge ranging from 224,780 to 265,570 cfs. Twenty such floods have happened in the last 2,000 years.

• A 1000-year flood would have a peak discharge ranging from 256,740 to 310,770 cfs. Four such floods have happened in the last 2,000 years.

• Source: A 2000 year natural record of magnitudes and frequencies for the largest Upper Colorado River floods near Moab, Utah. Noam Greenbaum, Tessa M. Harden, Victor R. Baker, John Weisheit, Michael L. Cline, Naomi Porat, Rafi Halevi, and John Dohrenwend; 2014.

TABLE: The data results of statistical floods and emperical floods

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FLOOD SCIENCE

• CLICK HERE FOR A PRESENTATION about flood hazards at Kings Bottom by John Weisheit, conservation director of Living Rivers & Colorado Riverkeeper. Note: this presentation was shared with the developer, engineer, attorney and our administrative agencies and elected officals.
• CLICK HERE TO LISTEN to Professor Victor Baker about paeleoflood hydrology. Science Moab, KZMU Community Radio.
• Read about the hundreds of paleoflood reports at this website.

• FEMA website for flood zones in Grand County, Utah

• Kane Creek PD Plat Map. jpg.