HIC MEETING July 12, 2005
Streamflow Regulation Accounting
by
Tom Gurss
Missouri Basin River Forecast Center
National Weather Service
Pleasant Hill, MO
REGULATION ISSUES
How do we provide long term probabilistic forecasts for locations heavily regulated for flood control, navigation, instream flows, irrigation, municipal water supply, power generation, etc.?
SRA GOALS
Evaluate existing data sources and modeling approaches and develop a generalized strategy to account for regulation in long-range forecasts.
Evaluate need for new tools, cost of development, and accuracy.
SRA TASKS
Phase 1--2004. Gather input and ideas from RFCs Develop strategies to better apply
current NWSRFS procedures Develop National Strategy Plan Develop South Platte
Implementation Plan as prototype model
Collect regulation data for South Platte River
SRA TASKS
Phase 2—2004-2005. Implementation of South Platte Plan on
Cache La Poudre River Basin Evaluate the strategies and identify
limitations in data, procedures and technologies
Test 3 different modeling approaches Evaluate effectiveness by generating
forecast verification statistics using hindcasting with ESPVS and ProbVS
Recommend Enhancements Update Strategy Plans as needed
SRA TASKS
Phase 2—2004-2005 (cont) Poudre River chosen because of
extensive available historical data Trans-basin imports Multiple upper elevation reservoirs Dozens of lower elevation off channel
storage areas Multiple re-use of irrigation water Base flows depend on return flows Water Rights huge factor as water is
traded between entities and storage facilities
SRA TASKS
Phase 2—2004-2005 Verification.
Evaluated 90-day probabilistic forecasts for April 1 and July 1 for volume, maximum, and minimum
Looked at RPS, RPSS, reliability, and discrimination
SRA TASKS
Phase 2—2004-2005 Results. Complex operations required to describe
psuedo reservoirs with very little data to adjust model to.
Verification showed some skill for maximum flows and volume, but little or no skill for minimum flows. Climatology better at some locations for low flows.
Verification statistics highly dependent on bin selection with limited sample size.
SRA TASKS Phase 3—2005-6.
Expand implementation plan into other sub-basins with less data, but similar regulation—Big Thompson and St. Vrain Rivers
Simplify strategy based on results of Phase 2
Generate verification statistics using hindcasting
Revise list of enhancements and strategy plans
SRA TASKS Phase 3—2005-6 Results.
Simplified operations provided similar verification statistics as the more complex operations for maximum flows, but little or no skill for minimum flows.
SRA TASKS
Phase 4—2006-8 (Proposed). Expand implementation into other
sub-basins with different types of regulation activities
Revise list of enhancements and strategy plans
Lessons Learned Poor verification statistics in low-flow
forecasts because of inability to adequately simulate human behavior’s effects
Data to support complex operations lackingOperational concerns using complex RES-J
operationsLimitations due to changing demands, uses,
and variance from rules.Tools Enhancements would simplify
operations
Future Concerns Need to decide whether low-flow forecasting of
streams with heavy regulation is adding value to historical distributions
Regulation in conjunction with Groundwater Pumping of Alluvial Aquifer
Power Generation
Large Multiple Reservoir System Simulation
Additional Tools Enhancements