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

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

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

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

System Schematic

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.

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

Zone-Based Prioritized Rule Set

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 1 2 3 0: Physical Capacity 1: IROC - 3000 cfs 2: Max Release - 10,000 cfs 3: Min Release – 700 cfs Allowable Range: 700-8000 cfs

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.

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

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

System Balance Definition

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

Conditional Rule Use If-then-else blocks

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. 60-40 split Sequential

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

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

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…

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

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

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.

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

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…

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

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

Downstream Ops & Rate-of-Change - Current

Downstream Ops & Rate-of-Change - New

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.

Contingency Factor

New - Inflow Multipliers

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