Wendy Welch and Andy Long: An updated groundwater model for regional planning – ChambersClover Creek Watershed, Pierce County

Hello! I’m your guest live blogger, Bonnie Becker from UW Tacoma.

The purpose of this USGS project is to update the groundwater model so that managers can prepare for future water demand.

Groundwater model has a larger study area (706 sq miles) than model area (491 sq miles). Includes Tacoma, Chambers Creek, part of Puyallup watershed. About 600K people getting water from this area.

Large advisory group included, 10 funding partners.

To develop a groundwater model, start with a conceptual model, and then the numerical model is built and calibrated empirically to match reality, as closely as possible.

It is really cool to see a 3-d model of the groundwater under my home city!

The model is based on 570 drillers logs. 6 aquifers in the area. Dozens of wells monitoring over many years.

The update will include recharge from precipitation, losing streams, seawater infiltration. Also new discharge elements and some technical model refinements.

Model can run a number of scenarios, such as a drought, increase in population, withdrawal from deeper aquifers.

How will this be used by stakeholders? Water rights disputes, resource planning, understanding impacts salmon habitat (connection between groundwater and streams). Can embed site specific models at higher resolution for needed projects and questions.



Can the model be used to predict flow between groundwater and seawater? It’s complex, but they are working on some fixes to possibly make this work.

Why did the stakeholders get involved, what did they want to know, and what answers have come out that have been meaningful to them? There was so much buy-in from beginning, didn’t want a model that sat on a shelf. Working together, the costs were much lower than trying to model each area separately.


And now, LUNCH!







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