Managing Reservoir Storage for Instream Flow

Waddle, Terry; ,

Managing Reservoir Storage for Instream Flow

by Terry Waddle, U.S. Fish and Wildl. Serv., Fort Collins, United States,

Document Type: Proceeding Paper

Part of: Water Management in the '90s: A Time for Innovation

Abstract:

Two possible approaches to using a portion of reservoir storage to supply instream flows are 1) to determine a fixed amount to be released each year as minimum instream flows and 2) to set aside a fraction of storage and inflow for instream management. An example is presented showing operations of these two alternatives to provide instream habitat below a reservoir. A simplified fish population index model, the effective habitat time series, is used to determine when water budget releases will produce habitat benefits. The effective habitat time series acts as a surrogate for fish population and reflects the mid to long term influence of water management decisions on the life cycle of a fish species. An operation rule for the storage account that considers habitat events is developed. The paper contrasts the fish habitat benefits of storage account operation with the fixed minimum flow approach.

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