Warming of the Willamette River, 1850–present: the effects of climate change and direct human interventions
- 1Civil and Environmental Engineering, California Polytechnic State University, San Luis Obispo, California
- 2Civil and Environmental Engineering, Portland State University, Portland, Oregon
- 3Coastal Sciences Division, Pacific Northwest National Laboratory, Sequim, Washington
- 4School of Environmental and Forest Sciences, University of Washington, Seattle, Washington
- 1Civil and Environmental Engineering, California Polytechnic State University, San Luis Obispo, California
- 2Civil and Environmental Engineering, Portland State University, Portland, Oregon
- 3Coastal Sciences Division, Pacific Northwest National Laboratory, Sequim, Washington
- 4School of Environmental and Forest Sciences, University of Washington, Seattle, Washington
Abstract. Using archival research methods, we found and combined data from multiple sources to produce a unique, 140 year record of daily water temperature (Tw) in the lower Willamette River, Oregon (1881–1890, 1941–present). Additional daily weather and river flow records from the 1850s onwards are used to develop and validate a statistical regression model of Tw for 1850–2020. The model simulates the time-lagged response of Tw to air temperature and river flow, and is calibrated for three distinct time periods: the late 19th, mid 20th, and early 21st centuries. Results show that Tw has trended upwards at ~1.1 °C /century since the mid-19th century, with the largest shift in January/February (1.3 °C /century) and the smallest in May/June (~ 0.8 °C /century). The duration that the river exceeds the ecologically important threshold of 20 °C has increased by ~20 days since the 1800s, to ~60 d yr-1. Moreover, cold water days below 2 °C have virtually disappeared, and the river no longer freezes. Since ~1900, changes are primarily correlated with increases in air temperature (Tw increase of 0.81 ±0.25 °C) but also occur due to increased reservoir capacity, altered land use and river morphology, and other anthropogenic changes (0.34 ±0.12 °C). Managed release of water influences Tw seasonally, with an average reduction of 0.27 °C and 0.56 °C estimated for August and September. System changes have decreased daily variability (σ) by 0.44 °C, increased thermal memory, and reduced interannual variability. These system changes fundamentally alter the response of Tw to climate change, posing additional stressors on fauna.
Stefan A. Talke et al.
Status: open (extended)
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RC1: 'Comment on egusphere-2022-793', Anonymous Referee #1, 27 Oct 2022
reply
Review of the manuscript: "Warming of the Willamette River, 1850–present: the effects of climate change and direct human interventions" by Talke et al. In its current state, it is far from a scientific research paper, instead a technical report. Most of the content in the discussion of results and conclusions are merely descriptions of their results and a list of general knowledge without any significant novel contribution. If the authors manage to rewrite the manuscript some notes about minor details are below:
- What are exactly system changes mentioned in the short summary? Authors should use some related technical terms.
- What is the novelty of this paper? Can the author mention some scientific applications including the novel idea?
- Line 87-88: The statement is not clear. How warming climate and hotter extremes are linked to land-use changes?
- Line 97-98: What is the characterization of natural variability? How it is linked to climate change?
- Line 100-101: What are the natural and background condition? Please mention.
- Line 106: What are chronic and acute anthropogenic factors? Describe with some examples.
- Line 114-120: Remove these results from the introduction section.
- Line 122: Study area will be more appropriate than the setting.
- Section 2 and its subsequent sections are quite lengthy and not clear. This should be short, precise and reader-friendly. Some results are discussed in this section which should be moved to the result and discussion section.
- Importance is given to the derivation of Tw in this paper while the paper tile is suggesting the impact of climate change and direct human intervention. Authors can change accordingly.
- Can uncertainty be assessed using RMSE? Any reference to this statement? Or authors can consider separate uncertainty analysis.
- Section 3.3.1: How the authors have evaluated the % of Tw change (mentioned in short summary that 30% from system change and 70% from climate change)?
- Have the authors used any particular separation/attribution analysis? If not then how % of the contribution is shown?
- Line 746: How the authors used the sensitivity studies? Describe it in methodology.
- Line 782: How are the system changes estimated by changing regression coefficients? Please explain.
- In Section 2, several anthropogenic factors are discussed. The authors should consider these factors in attribution analysis.
- What is the significance of precipitation in this work? As precipitation is an important climatic variable, it can't be ignored in this analysis. The authors can refer following articles. (* Swain, S. S., Mishra, A., Chatterjee, C., & Sahoo, B. (2021). Climate-changed versus land-use altered streamflow: A relative contribution assessment using three complementary approaches at a decadal time-spell. Journal of Hydrology, 596, 126064. * Liang, S., Wang, W., Zhang, D., Li, Y., & Wang, G. (2020). Quantifying the impacts of climate change and human activities on runoff variation: case study of the upstream of Minjiang River, China. Journal of Hydrologic Engineering, 25(9), 05020025.)
- Figures should not be cited in the conclusion. Please rewrite this section.
- Line 902: The citation of Jay and Naik, 2011 is wrong. Citations should be in a uniform manner followed by HESS guidelines.
- Proper proof-reading is needed, but more importantly, better use of technical language and precise description is lacking throughout the manuscript.
Stefan A. Talke et al.
Stefan A. Talke et al.
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