Updates to models of streamflow and water temperature for 2011, 2015, and 2016 in rivers of the Willamette River Basin, Oregon

First posted June 6, 2022 For additional information, contact: Director, Oregon Water Science CenterU.S. Geological Survey2130 SW 5th AvenuePortland, 97201 Mechanistic river models capable of simulating hydrodynamics and stream temperature are valuable tools for investigating thermal conditions their relation to streamflow in basins where upstream water storage management decisions have an important influence on reaches with threatened fish populations. In the Willamette River Basin northwestern Oregon, a two-dimensional, hydrodynamic water-quality model (CE‑QUAL‑W2) has been used investigate downstream effects dam operations other anthropogenic influences temperature. By managed releases various temperatures from large Valley Project dams modeling domain, these can be riverine determine when most challenging populations how flow affect optimize river.The original were initially developed simulate spring–autumn 2001 2002. This report documents (1) upgrade CE‑QUAL‑W2 version 4.2 (2) update those that occurred March through October 2011, 2015, 2016. These years selected represent range climatic hydrologic Basin, including “cool, wet” year (2011), “hot, dry” (2015), “normal” (2016). Six submodels comprise system updated this report; each submodel run independently or others as system. include Coast Fork Middle submodel, which includes Rivers, Row River, Fall Creek; McKenzie South Cougar Dam its confluence mouth; Santiam comprises Foster River; North Big Cliff Dam; Upper Eugene Salem; Salem Falls near City.The included originally developed, calibrated, documented by researchers. As part updates described here, some parameters adjusted improve stability decrease runtime. Boundary meteorological, hydrologic, many cases, data sources drive 2002 no longer available, required use new sources, determination proxy record, development appropriate estimation techniques. Goodness-of-fit statistics show good fit, subdaily at comparable locations mean absolute error generally less than 1 °C often nearing 0.5 °C, depending individual reasonably low bias. The produced highest bias any submodels. indicate results may biased cool (ranging -0.43 2016 -0.80 2011 results), but only available comparison is itself estimated, estimates known too high summer. Depending future needs, warrant further refinement, along collection properly define minimize