New US National Flood Frequency Guidelines
Research over the past 25 years has indicated that the U.S. National Flood Frequency Guidelines, last revised in 1982, need to be replaced or updated. These guidelines have an impact on water supply and availability for flushing flows, endangered species flows, river sediment management, reservoir management, storage and releases, and reservoir flood control storage.
* How can we best document and complete testing of new US flood frequency guidelines so that water-resources managers can fully utilize the new methods?
This Science and Technology (S&T) Program research project is a demonstration and documentation effort and is based on work completed in fiscal year (FY) 2007 on testing proposed new guidelines. A guidelines report and two journal articles are proposed in this effort in partnership with the U.S. Geological Survey and Reclamation's Dam Safety Office.
Need and Benefit
Reclamation has a clearly defined need and benefit in this flood frequency research. The results of this work will be widely applied, in conjunction with paleoflood data, in estimating hydrologic hazard curves for all Reclamation dams as part of the Dam Safety Program.
The guidelines that result from this research will also have impacts on the following water supply and availability areas within Reclamation. It can impact flood control operations and rule curves at Reclamation reservoirs with dedicated flood control space such as Folsom and Pueblo Dams, and the Lower Colorado River below Hoover Dam. It can affect flood flow calculations that dictate limits on flushing flows, operational releases and clearances for downstream structures such as those on the Trinity River downstream of Lewiston Dam. The guidelines can impact flow estimates and required releases for endangered species such as on the Middle Rio Grande. In addition to Reclamation benefits, the research has broad benefits to the National Flood Insurance Program and can impact design and assessment of hydraulic structures (bridge crossing, levees, etc.) throughout the United States. The end result is more accurate estimates of flood flows (with uncertainty) that can result in water savings and potential cost avoidance.
This demonstration and documentation research effort is the final step in technology transfer of new and improved flood frequency methods into guidelines for national use. The research on the methods has been completed (Cohn et al. 1997, Cohn et al. 2001, England et al. 2003a, England et al. 2003b, Griffis et al. 2004). The testing plan has been developed (HFAWG 2006) and results of the testing are nearing completion (England and Cohn 2007). The final step is documentation. The end research result is new National Flood Frequency Guidelines.
Contact the Principal Investigator for information about these documents.