US Army Corps of EngineersBUILDING STRONG®

Reservoir Simulation Software“Westfield Sub-basin”

Presenter – John Hickey, HECAugust 2010

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HEC-ResSim

• Simulate the influence of reservoirs and diversions on flows in a river system.

• Decisions about reservoir releases are made in accordance with user-defined rules.

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Connecticut River Basin 44 Sub-basins 60+ Large Reservoirs 143 Ecological points of

interest 320+ SYE inflow

hydrographs 362 River Reaches

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Westfield Subbasin - Case Study• Multi-purpose operations (flood management,

hydropower, water supply)• Varied ecological concerns (floodplains, salmon

stocking, diadromous fish)Also…• Availability of

hydrologic data• One of first

subbasins to have working simulation and optimization models

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Reservoirs on the Westfield• The Westfield consists of three major

dams essentially running in parallel. Knightville Littleville Cobble Mountain/Borden Brook

• Flood management, hydropower, and water supply objectives are prevalent within the sub basin Knightville – Flood Management Littleville – Flood Management Cobble Mountain/Borden Brook –

Hydropower and water supply

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Physical Information for Model• Physical Components:

Reservoir Pool Dam (and its Outlets) Diverted Outlets

• Hierarchical Outlet Structure

• Multiple outlet types• Diverted Outlets• Hydropower Outlets

Capacity Efficiency

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Operational Rule Blocks• Priority based • Rules at the Dam• Rules for downstream

locations• Rules on individual outlets• Rules for other locations• Various types of rules

Min/Max release Rate of Change Downstream Control Hydropower Scripting

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At Site Operations• Knightville Dam: max

flood release of 4,500-cfs.• Littleville Dam: max flood

release of 1,500-cfs.• Borden Brook Mountain

Dam: max flood release of 1,675-cfs.

• Cobble Mountain Dam: max flood release of 1,675-cfs.

• Knightville and Littleville Dam have minimum flows that are a function of season and reservoir inflow.

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System Operations within TributaryWhen two or more reservoirs operate for one site, ResSim uses a “system” operation that balances storage in the pools.

Knightville and Littleville operate to control flows at Westfield to not exceed 11,250 cfs.

Westfield

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System Operations for Mainstem

Hartford

Knightville and Littleville operate to reduce outflows if Hartford experiences high stages.

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Model Output

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Purpose ResSim will be used to regulate and route

hydrographs downstream. Various reservoir management scenarios

can be developed by changing rule sets for the involved project(s).

Regulated hydrographs for each scenario will be used to assess flow conditions at points of interest.