20 Hydrogeology and Marine/Coastal Geoscience
This session covers aspects related to SGDs & their associated aquifers, including but not limited to: water–rock interaction, coastal aquifer contamination, geochemical transformation, hydrological flows, saline intrusion, coastal estuaries, and environmental, economic, and social SGD-related issues.
Thursday, 23 April 2026
8:00 AM - 10:00 AM
LMH, Meeting Room
Leveraging rain and water flow data to tune a high-resolution Hydrologic Model of the Coos Watershed, Oregon
Paper number: 20-2
Program: Technical Sessions
Time: 8:30 AM – 8:45 AM
Authors
Abstract
Accurate surface water modeling in coastal watersheds is essential for habitat restoration and water resource management. This study presents progress developing a tuned hydrologic modeling framework for the Coos Watershed, Oregon. The Muskingum-Cunge method (MCM) on top of an upslope area model is used to interpolate a higher resolution local hydrologic model out of Oregon State’s PRISM weather model. Initial guesses for roughness and infiltration coefficients will be refined by Bayesian Optimization (BO), using stream flow data.
For precipitation data, we use PRISM climate data at an 800-meter spatial with a 6-hour temporal resolution, though it also gets upscaled by ‘clipped’ cubic interpolation to fit into the upslope area model.
To characterize the physical landscape, we employed an upslope area model derived from the local digital elevation model (USGS 1m Lidar). Infiltration coefficients were assigned to discrete domains based on the regional USGS geological map, so that coefficients remain consistent within unified lithological units. Surface hydraulic roughness was parameterized using USGS Land Cover Data (LCD). Surface water routing is executed using the MCM with output in 1-hour increments.
With assistance from the Coos Watershed Association, this model can now be calibrated downstream against flow gauge data. We will now use BO to iteratively refine roughness and infiltration coefficients each month for the next couple of years. With luck, this BO method will help the model converge to a reasonably well tuned near real time Hydrologic Model of the Coos Watershed. In the meantime, the model will be used qualitatively to develop a more specific understanding of upstream hydrologic conditions during the year to assist Coho salmon habitat rehabilitation.
If the infiltration and roughness parameters can be properly tuned, this rain and flow model framework could help check on the accuracy of weather models, potentially worthwhile for rural or mountainous locations, including Coos Bay, where standard weather radar data isn’t available, or even provide more granular flood hazard data for small channels in complex terrain.
Geological Society of America Abstracts with Programs. Vol. 58, No. 3
doi: 10.1130/abs/2026CD-411047
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