by KeAi Communications Co., Ltd.
In the Western US, water scarcity is a pressing issue, and there is a balance between flow as needed to support migratory fish habitats, such as salmon and steelhead.
Simultaneously meeting the needs of irrigators and hydropower producers has proven to be a unique challenge. Even with enough stored water available, it can still be difficult to coordinate flow releases that satisfy all needs. As climate conditions continue to grow warmer and drier, finding solutions that simultaneously meet the needs of fish, energy production, and other water needs will become more challenging.
To that end, two scientists at Oak Ridge National Laboratory investigated the optimal scheduling of flow releases from a reservoir in California, US, to simultaneously benefit salmon populations and maximize power generation. . The study’s findings were published in the journal Water Security and Biology.
“Tensions among competing water uses are high in California’s Central Valley,” explained Henriette Jager, co-author of the study. “Reservoirs serve many purposes, including support for migratory fish populations. Wild spawner returns of fallen Chinook Salmon to Central Valley rivers have declined at an average rate of 1,947 adults. every year since 1950, with many year-to-year fluctuations.”
The duo developed models to understand how flow releases from a California reservoir could be scheduled to benefit salmon while maximizing the amount of electricity generation. Dr. Rocio Uria-Martinez, an energy economist, models seasonal patterns in energy costs, while Dr. Jager models salmon responses to flow.
When combined in an optimization, the models produce a Pareto-optimal frontier of time flow patterns. The candidate flow regimes consist of two pulse flows with differences in magnitude, time and duration. These regimes are further constrained by maintaining an overall annual run near the historical median.
The results of the study show if the flow regimes that are good for salmon rearing will also allow the production of hydropower in times of high electricity demand and prices. The analysis reveals times when economic and salmon goals align, as well as times when they diverge.
Optimal flow regimes that satisfy salmon and hydropower objectives provide pulses in early summer. However, the only solutions that emphasize the value of hydropower include high flows in the middle of winter.
According to another study author, Dr. Rocio Uria-Martinez, “The economy of the California grid is complex, but we are mainly interested in seasonal climate signals. For example, the demand for electricity should be higher when air conditioning and heating come on. ” The study results provide valuable insights into how reservoirs can operate to simultaneously meet the needs of salmon populations and power users.
More information:
Henriette I. Jager et al, Finding the middle ground: Flow regimes designed for salmon and energy value, Biology and Water Security (2023). DOI: 10.1016/j.watbs.2023.100183
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Citation: Salmon recovery: Conflicts between salmon needs and competing water users (2023, July 4) retrieved 4 July 2023 from https://phys.org/news/2023-07-salmon -recovery-conflicts-users.html
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