Visit by Government Officials from Mozambique COLUMBIA RIVER SYSTEM BRIEFING IV U.S. Army Corps of Engineers Northwestern Division North Pacific Water Management Portland, Oregon 15-16 October 2001
RESERVOIR CONTROL CENTER
HISTORIC PUBLICATIONS & EVENTS • House Document 103, 1932 • 1948 Flood (~ 20 dead, $100 million damages, thousands homeless) • Flood Control Act of 1950, Public Law 516 • Columbia River Treaty, signed January 17, 1961 • CRT-63, June 1991. Reduces flood control draft in moderate years • Feb. 1997, Prelim. study to reduce flood control draft on all projects (increases historic average regulated flow to 550,000)
OVERVIEW • Corps has Congressional Authority to Operate the Columbia as a Flood Control System to protect the Lower Columbia (rm 0-140) and Portland • Design Flood is 1894 • Local Flood Control is a By-Product of System Flood Control • System Level of Protection Greater than 300-year as appropriate
RESERVOIR DRAFT REQUIREMENTS • Varies Depending on Project • Based on Seasonal Volume Forecast • Storage Reservation Diagram (SRD) Converts Volume Forecast to Draft Requirement • SRDs in Place for: Mica, Arrow, Libby, Duncan, Hungry Horse, Grand Coulee, Dworshak, Brownlee.
OPERATING CONCEPTS • All Draft to be Completed by 30 April • System Flood Control Takes Precedence Over Local Flood Control • Initial Controlled Flow (ICF) at The Dalles Determined • Every Effort Made to Regulate at or Below the ICF • Underforecasted snowpack • Excessive rainfall during refill period • Refill Targets Change as a Function of the NWS’s Real-Time Forecasts • Grand Coulee is Regulated for The Dalles Only • “Zero Damage” is at 450,000 cfs
THE FLOOD OF 1996- Events • Winter 1995-1996 one of the wettest of record • Heavy Rains in Nov-January rapidly filled reservoirs earlier than normal • January: Heavy snow over Cascades due to northerly Arctic air + subtropical moisture • Jan-Feb.: very cold temperatures froze the saturated grounds. • Feb. 5: intense surges of subtropical moisture cause rapid snowmelt. Also, heavy precipitation (28” in 4 days). Mckenzie River flow jumped from 4,000 cfs to 20,000 cfs in 1 day. • 100-yr flood event. Recession started 10 February.
The Flood of Feb. '96 -- Operations • $3.2 billion in flood damage avoided from Portland to Astoria. • Releases reduced from US Federal and non-Federal dams and Canadian storage. • Grand Coulee power reduced from 4300 to 1300 Mw. In less than 6 hours, $5 million spent on replacement power (and $5 million in foregone sales). • Willamette Valley dams control 27% of the water in their Basin, and reduced river levels: 7.5’ in Salem and 9’ in Eugene. • Portland river crested 2” below seawall. Escaped up to $1.1 billion in estimated damages in Portland alone. • Flood control remains a central regional priority.
US Army Corps of Engineers
US Army Corps of Engineers North Pacific Division 1996 Northwest Winter Flood
Water Level without Dams 7 feet 1996 4.5feet 1964 (from water level)
Water Level without Corps Dams 7 feet 1996 5.5 feet 1964
1996 Flood – Cleanup • Navigation Locks seriously damaged • Serious shoal movement affecting Columbia shipping channels • Damages to dikes, levees, and bank protection • Log jams and debris affected recreation opportunities • Post-flood community workshops to share lessons learned and re-affirm roles and responsibilities of key response agencies. Teach flood fight techniques, safety and sand-bagging. • Oregonian, state’s largest newspaper, credited the Corps for saving downtown Portland.
1997 – Expected Runoff • Anticipated Flow • February Final Forecasts, for the April – August period:Final Grand Coulee 77MAF 126% of Normal • Lower Granite 36MAF 158% of Normal • The Dalles 125MAF 135% of Normal • Based on February Final Forecast, Possible Range of Peak Discharge: Low Flow,kcfsHigh Flow, kcfs • Lower Granite 220 320 • The Dalles 475 555
1997 – Observed Runoff • Actual Unregulated Runoff • Actual April – August runoff: Grand Coulee 83.3 MAF 137% of Normal • Lower Granite 35.3 MAF 153% of Normal • The Dalles 133 MAF 143% of Normal • Peak Discharges: Unregulated,kcfsRegulated, kcfs • Lower Granite 358 225 • The Dalles 896 571 • 1997 was the largest runoff since 1894. • The Columbia River at Vancouver, Washington was above flood stage most of May and June. • Over $4.2 billion in damages prevented during the spring snowmelt runoff. • Peak observed stage at Vancouver, Washington was 19 feet. The unregulated peak stage would have been 28.4 feet. Flood stage is 16 feet, Major flood stage is 26 feet.
1997 Contingencies • Special briefings for stakeholders and customers by Corps Commanders and staff • Irrigators around reservoirs • Other Agencies’ Regional Executives • Press Releases were ongoing • Detailed, adaptive Planning was ongoing • Regional stakeholders received continuous coordination