Floodstage Spring 2002 Issue - Laserfiche WebLink

Home Browse Search

South Boulder Creek The City of Hydrology Advisory Panel Boulder Floodplain and Wet- lands Coordinator, Alan Taylor, has organized a Hydrol- ogy Advisory Panel (HAP) to evaluate South Boulder Creek flood hydrology and to generate a scoping docu- ment to guide a future detailed analysis of the water- shed. The city hopes that the effort will lead to consistent and uniform re- evaluations of all 13 major drainage ways that affect Boulder. The HAP consists of a group of professionals that repre- sent various areas of expertise related to climatology, meteorology, hydrology, paleohydrology, hydraulics, GIS applications, and related fields. {HAP members include: Tom Browning, Nolan Doesken, Bob Jarrett, Lynn John- son, George Leavesly, John Liou, Pedro Restrepo, Kevin Cherry -Creek PMP Study The CWCB and its contractor, Applied Weather Associates (AWA), are nearing completion of an independent review of the Site Specific Probable Maximum Precipitation Study (PMP) done for Cherry Creek Reservoir in 1995 by the National Weather Service (NWS) and the Corps. PMP studies are used in dam design and safety calculations. Rather than use federally standardized Hydro - Meteorological reports and manuals, the study team developed input parameters and precipitation totals from local extreme storms that better represent Colorado's climate. An interim report is out and a final report is due in July 2002. The report will address the Probable Maximum Flood Study issues as previously stated at Corps public meetings. After months of controversy local, state and federal experts are working together on the PMP Study concerns. The controversy over Cherry Creek Reservoir has spurred national interest. Recently the National Weather Service agreed to review and participate on the CWCB /AWA report. The NWS participation on the technical Stewart and Gilbert White, and are supported by Alison Burchell, Molly Tayer (facilitator) and Mr. Taylor). The HAP generally meets every other week and is focused on technical assessment and scoping activities to identify all critical elements for a South Boulder Creek watershed - modeling project. The HAP is tasked with developing specific study ele- ments such as analytical tools and methodologies in ad- dition to data and information resources. A long history of previous studies of South Boulder Creek, beginning with the original 1969 study by the U.S. Army Corps of Engi- neers, has been under review and scrutiny by specialists and interested parties largely precipitated by a University of Colorado land purchase. It is the goal of the HAP to generate an unbiased hydrologic approach to water- shed modeling for South Boulder Creek. review team should give the Corps the confidence needed to proceed with resolving issues and implementing recommendations regarding Cherry Creek Reservoir dam safety. The Corps is awaiting the findings and recommendations from the PMP Study Review to determine what avenues to follow in addressing Cherry Creek Dam safety issues. For more information call Larry Lang at (303) 866 -3989. r.wr *� 5 0 AWA used G.I.S. to plot storm isohyetal patterns for design storms for the original study (below is the June 17, 1965 storm), the Cherry Creek ba- sin is in red. 2001 Flood Documentation The CWCB annually documents flooding events. Last year was a relatively light flooding year, with no state- wide flooding events. The report was prepared by URS Corporation and it collected data on the storm events, ex- tent of flooding and dam- ages for selected events. The 2001 report covers July 14— Greeley, mid -July to August Meeker /Rio Blanco County, August 14 —New Cas- tle, September 13— Palisade/ Grand Valley, September 16— Colorado Springs,, and September 17— Telluride to Placerville (San Miguel County). The Meeker /Rio Blanco event on August 8, saw several inches of rainfall and triggered mudslides and rockslides. NOAA reported five inches of rain fell in a 2 -3 hour period which exceeds the 100 -year frequency event. Damages were esti- mated at $2.8 million with most of the cost covered by CDOT for clean up of road- ways, culverts and drainage ditches. For more information call Tom Browning at (303) 866 -4804.