When most people hear the word “models,” they think of runways and fashion trends. But for those interested in water issues, the word “models” has a completely different meaning – and predicts completely different trends.
The Colorado River Basin serves more than 40 million people in seven U.S. states and part of the northwest Republic of Mexico. Colorado River flows are highly variable, especially given the effects of drought and climate change, but the storage built into the system makes it more resilient. The Colorado River Basin has two enormous reservoirs (the two largest reservoirs in the United States) – Lake Powell and Lake Mead, which are operated under a system called conjunctive management.
In order to determine the current and potential future health of the reservoirs and our water supply, hydrologists use various “models.” Here’s a quick look at three hydrologic models used to give us a glimpse into our water future in the Colorado River Basin.
24-Month Study
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Use:
Forecasting that informs near-term decision-making regarding the conjunctive management of Lakes Powell and Mead
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Timeframe:
Forecasting the next two years
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Output:
Minimum, maximum and most probable scenarios
Mid-term Probabilistic Operations Model (MTOM)
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Use:
Determining risks and vulnerabilities for the subsequent 2 to 5 years
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Timeframe:
One to five years
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Output:
Planning for the elevations of both reservoirs, release from Lake Powell to Lake Mead and shortage levels for Lake Mead
Colorado River Simulation System (CRSS)
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Use:
Long-term planning tool to evaluate potential future policy decisions
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Timeframe:
10-50 years
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Output:
Large-scale trends and probabilities that can inform future reservoirs operating rules and water use planning
Currently the Arizona Reconsultation Committee is working to develop our state’s guiding principles as new operating rules are being developed for the Colorado River Basin to take effect in 2026. The Committee has convened a technical work group, the Modeling and Analysis Work Group, to use information from these hydrologic models to help inform the Committee’s proposals and recommendations.
