1. HEC-ResSim Enhancements
Better Tools to Simulate the Operation of California Reservoirs
Joan Klipsch
CWEMF Annual Meeting
February 2007

2. Outline HEC-ResSim Basics The Yuba-Feather F-CO Study
Development Objectives
The System Schematic
Rule-Base Operations Definition
New Features in Version 3.0
The Yuba-Feather F-CO Study
Participants
Objective
MOA
Requested Enhancements for Version 3.1

3. ResSim Development Goals
Represent the physical system as realistically as possible.
Reproduce the decision making process that reservoir operators use to set releases.
Support Multi-Purpose Operation Schemes
Represent both Flood Control Constraints & Conservation Goals
Support low flow & drought operation
Support environmental restoration investigations

4. The Physical System Graphical System Schematic
Reservoirs
Reaches
Junctions
Diversions
Diverted Outlets
Hierarchical Multiple Outlet Structure
Controlled and Uncontrolled Outlets
Power Plants
Pumps
Outlet Groups

5. System Schematic

6. Rule-Based Reservoir Operations
Guide-Curve
The seasonally-variable Desired Pool Elevation
Basic Guide Curve Operation:
“Release or store to get back to guide curve.”
Zones
Zones partition reservoir storage among different purposes.
A prioritized set of rules within each zone limits or overrides basic guide curve operation.

7. Rule-Based Reservoir Operations
Rules
A rule is an objective for, or constraint on, the operation of a reservoir or system of reservoirs.
Rule Types:
Flexible Local & Downstream Flow Objectives
Release or Pool Elevation Rates of Change
Emergency Gate Regulation & Induced Surcharge
Local and System Hydropower Requirements
Tandem Operation
Pump-back Schedule
User-scripted rules

8. Zone-Based Prioritized Rule Set

9. Allowable range of releases (cfs)
Basic Decision Logic
Determine the… Allowable Range of Releases
Physical Capacity defines the initial range
Rules narrow the range
Determine the… Desired Guide Curve Release
How much the reservoir should store or release to get back to guide curve in this timestep
Allowable range of releases (cfs)
15,000
10,000
5,000
0: Physical Capacity
1: IROC cfs
2: Max Release - 10,000 cfs
3: Min Release – 700 cfs
Allowable Range: cfs

10. Basic Decision Logic, Cont’d.
Decide ! ?
Is the Desired Guide-Curve release within the allowable range?
Yes
Make the Desired GC release No
Make the allowable release that is closest to the Desired GC release.

11. Other Important Operations Features
Tandem and Parallel System Operations
With variable storage balancing definition
Conditional (If-then-else) Rule Activation
Release Allocation – Outlet Prioritization
User Scripted Rules & State Variables
Outlet Outages & Capacity Overrides

12. Tandem & Parallel System Operations
El Vado to Abiquiu
Abiquiu to Cochiti
Parallel
Cochiti & Jemez

13. System Balance Definition

14. Conditional Rule Use Atwood & Leesville “watch” Dover – Not true Tandem

15. Conditional Rule Use If-then-else blocks

16. Release Allocation
To provide control over how the releases are allocated to the available outlets
Two methods
Balanced
Even Balance (default)
Un-even Balance – e.g split
Sequential

17. Storage Integration Scheme
Solution to the problem that occurs when a reservoir has:
Small storage
Large outlet capacity
More inflow than can be stored during a time-step

18. Trials Simulation ‘copies’ of an alternative
Provides extended “what-if” analysis

19. New Development – FY07 R&D Funded Project Funded
Routing Enhancement for Downstream Ops
Tailwater-Dependent Outlet Capacity
Technical Reference Manual
Project Funded
LCRA
Projected Pool Operation
Yuba-Feather F-CO Study…

20. Forecast-Coordinated Operations
Yuba-Feather Watershed
Oroville - Operated by CA DWR
New Bullards Bar - Operated by Yuba County Water Agency
Study Objectives
Develop a way to coordinate flood control releases from the two reservoirs, at the same time maintaining channel flow at or below the channel capacity at Marysville

21. Forecast-Coordinated Operations
Study Team
Yuba County Water Agency
California Dept. of Water Resources
NWS CA-NV River Forecasting Center
Advisory: Sacramento District, USACE
Funding
(new) Prop 13 Grant

22. Yuba-Feather F-CO
SPK Water Management was consulted on existing models for the basin.
Study team chose ResSim for the operations modeling tool.
SPK & Study Team identified some modifications that would be needed to effectively represent the watershed.

23. Identified Enhancements
Phase 1
Downstream operation must respect rate-of-change constraints
Improve Induced Surcharge operation algorithm to remove oscillations
Induced Surcharge function inadequate to represent ESRD operations.
Provide option to enter ESRD curves directly
Add a “Hold the Gate” option for falling pool operation

24. Identified Enhancements
Phase 1, cont’d.
Add a variable contingency factor to the downstream control rule to represent uncertainty in the inflow forecast
Add a inflow factor editor to facilitate development of “what-if” inflow scenarios
Phase 2
Add ensemble management to alternative development
Add ability to impact operations based on probability…

25. MOA with HEC Yuba County Water Agency NWS 1+ year in development
Effort failed over liability issues
NWS
3-6 months in development
Success!

26. Additional Requirements
NWS-RFS integration
Hot-start Feature
Headless Operation
Port to Linux

27. Downstream Ops & Rate-of-Change - Current

28. Downstream Ops & Rate-of-Change - New

29. New - Contingency Factor
Effective space at the downstream control location is computed as the difference between the downstream limit modified by the contingency percentage and the cumulative local flow.
For a downstream maximum flow rule, the downstream limit is multiplied by (1 – contingency percentage/100), resulting in a reduced maximum limit.

30. Contingency Factor

31. New - Inflow Multipliers

32. More Info… Version 3.0, Release March 2007 !!! HEC’s Web Site:
HEC’s ResSim Point of Contact:
Joan D. Klipsch
Hydrologic Engineering Center