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Liam N Schenk

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Annual stream loads of mercury (Hg) and inputs of wet and dry atmospheric Hg deposition to the landscape were investigated in watersheds of the Western United States and the Canadian-Alaskan Arctic. Mercury concentration and discharge data from flow gauging stations were used to compute annual mass loads with regression models. Measured wet and modeled dry deposition were compared to annual stream loads to compute ratios of Hg stream load to total Hg atmospheric deposition. Watershed land uses or cover included mining, undeveloped, urbanized, and mixed. Of 27 watersheds that were investigated, 15 had some degree of mining, either of Hg or precious metals (gold or silver), where Hg was used in the amalgamation process....
Categories: Publication; Types: Citation
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Input and results from boosted regression tree and artificial neural network models that predict daily maximum pH and daily minimum dissolved oxygen in Upper Klamath Lake, 2005-2019
This data release contains the model inputs, outputs, and source code (written in R) for the boosted regression tree (BRT) and artificial neural network (ANN) models developed for four sites in Upper Klamath Lake which were used to simulate daily maximum pH and daily minimum dissolved oxygen (DO) from May 18th to October 4th in 2005-12 and 2015-19 at four sites, and to evaluate variable effects and their importance. Simulations were not developed for 2013 and 2014 due to a large amount of missing meteorological data. The sites included: 1) Williamson River (WMR), which was located in the northern portion of the lake near the mouth of the Williamson River and had a depth between 0.7 and 2.9 meters; 2) Rattlesnake...
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This model archive summary (MAS) is a model update to an existing log-transformed turbidity-suspended sediment concentration (SSC) regression model computing SSC for water year (WY) 2008-2017. This model supersedes all models prior to Oct 1, 2017 and includes a new model for WY 2018-2020. The methods used follow USGS guidance as referenced in Office of Surface Water (OSW)/Office of Water Quality (OWQ) technical memoranda 2016.07 and USGS techniques and methods, book 3-chapter C4 (Rasmussen and others, 2009).
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This model archive summary (MAS) documents the revision of suspended sediment concentration (SSC) unit and daily values computed from WY 2008-2017, and the additional computation of SSC unit values from WY 2018-2020 using a new log-transformed regression model with SSC samples from the period of record at this site. The new, revised model computes SSC unit values for WY 2008-2020. This model supersedes all prior models for this site. Prior approved models were simple linear, non-transformed regressions with turbidity as the explanatory variable. Evaluation of 90 percent prediction intervals after the records were approved showed that negative values were being reported during periods of low turbidity. As a result,...
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This product summarizes the collection and analysis of bed material sample grain size distribution collected from the Iron Gate, Copco, and J.C. Boyle Reservoirs located in Northern California and Southern Oregon on the Klamath River. Samples were collected on June 16, 2020 from cores (less than 1m depth) and processed for the full size distribution.
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