High and average groundwater-table estimates for areas near the southern part of Puget Sound, Washington

Bias-corrected estimates of high and average water table elevation and depth below the land surface were generated for areas near the southern part of Puget Sound, Washington, on a 500‑ft‑by‑500‑ft grid. Simulated water table elevations were extracted from two published U.S. Geological Survey groundwater flow models, the Southeast Sound (SES) model (Long and others, 2024) and the Kitsap Peninsula model (Frans and Olsen, 2016), by identifying the heads in the uppermost saturated model layer at each horizontal grid cell. The water table was extracted for two conditions: an average water table from steady-state simulations, and a high water table from transient stress periods that were most similar on average to the high mean monthly value for the model simulation periods. Because regional groundwater models cannot perfectly match observations at all locations and times, a bias correction was applied to adjust for locations where simulated water tables were higher or lower than measured water levels. Bias correction factors were computed at observation wells by comparing simulated water table elevations to observed water levels compiled from the USGS National Water Information System (NWIS) and the Pierce County Water Data Viewer. Model General Head Boundary (GHB) cells along Puget Sound were assigned a bias correction factor of zero and model GHB cells at lakes were assigned to lake levels to constrain the interpolated bias surface at these boundaries. A continuous bias correction surface was interpolated from these point values using the Spline with Barriers tool in ArcGIS Pro and added to the simulated water table at each grid cell to produce bias-corrected water table elevation estimates. Depth to the water table was calculated as land surface elevation minus bias-corrected water table elevation, with a minimum value of 2-feet where the estimated water table was at or above 2-feet below the land surface. This data release includes the final bias-corrected water table elevation and depth rasters and shapefiles, the input datasets used in the bias correction process (simulated water table surfaces, bias correction point data, bias correction surfaces, and land surface elevation), and a study area boundary polygon.

References:

Frans, L.M. and Olsen, T.D., 2016, Numerical simulation of the groundwater-flow system of the Kitsap Peninsula, west-central Washington (ver. 1.1, October 2016): U.S. Geological Survey Scientific Investigations Report 2016–5052, 63 p., http://dx.doi.org/10.3133/sir20165052.

Long, A.J., Wright, E.E., Fuhrig, L.T., and Bright, V.A.L., 2024, Numerical model of the groundwater-flow system near the southeastern part of Puget Sound, Washington, v. 2 of Welch, W.B., and Long, A.J., eds., Characterization of groundwater resources near the southeastern part of Puget Sound, Washington, 2 chap. (D–E): U.S. Geological Survey Scientific Investigations Report 2024–5026–D–E, [variously paged; 103 p.], https://doi.org/10.3133/sir20245026v2.


Disclaimers:

During metadata preparation, the generative AI tool Kiro version 0.12.333 was used to improve grammar, clarity, and coherence of the text. All AI-generated suggestions were reviewed, revised as needed, and approved by the authors to ensure accuracy and maintain the integrity of the scientific content.

AI-assisted coding tools Kiro version 0.12.333 and Perplexity were employed to generate code used to process MODFLOW output from the two groundwater flow models used in this work. All code was reviewed, tested, and validated by the authors to ensure correctness and reproducibility.

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