the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Modelling the effects of climate and landcover change on the hydrologic regime of a snowmelt-dominated montane catchment
Russell S. Smith
Caren C. Dymond
David L. Spittlehouse
Rita D. Winkler
Georg Jost
Abstract. Climate change poses risks to society through the potential to alter peak flows, low flows, and annual runoff yield. Wildfires are projected to increase due to climate change; however, little is known about their combined effects on hydrology. This study models the combined impacts of a climate change scenario and multiple landcover scenarios on the hydrologic regime of a snowmelt-dominated montane catchment, to identify management strategies that mitigate negative impacts from climate and/or landcover change. The combination of climate change and stand replacing landcover disturbance in the middle and high elevations is predicted to advance the timing of the peak flow three to five times more than the advance generated by disturbance alone. The modelling predicts that the combined impacts of climate change and landcover disturbance on peak flow magnitude are generally offsetting for events with return periods less than 5–25 years, but additive for more extreme events. There is a dependency of extreme peak flows on the distribution of landcover. The modelling predicts an increasing importance of rainfall in controlling peak flow response under a changing climate, at the expense of snowmelt influence. Extreme summer low flows are predicted to become commonplace in the future, with most of the change in frequency occurring by the 2050s. Low annual yield is predicted to become more prevalent by the 2050s, but then fully recover or become less prevalent (compared to the current climate) by the 2080s, because of increased precipitation in the fall-spring period. The modelling suggests that landcover disturbance can have a mitigative influence on low water supply. The mitigative influence is predicted to be sustained under a changing climate for annual water yield, but not for low flow. The study results demonstrate the importance of a holistic approach to modelling the hydrological regime rather than focusing on a particular component. Moreover, for managing watershed risk, the results indicate there is a need to carefully evaluate the interplay among environmental variables, the landscape, and the values at risk. Strategies to reduce one risk may increase others, or effective strategies may become less effective in the future.
- Preprint
(5995 KB) - Metadata XML
-
Supplement
(3069 KB) - BibTeX
- EndNote
Russell S. Smith et al.
Status: open (until 28 Dec 2023)
-
RC1: 'Comment on hess-2023-248', Anonymous Referee #1, 13 Nov 2023
reply
Review for manuscript ‘Modelling the effects of climate and landcover change on the hydrologic regime of a snowmelt-dominated montane catchment’ by Smith et al.
Summary
The manuscript by Smith et al. assesses the combined impacts of climate and landcover scenarios on different hydrological signatures in the Penticton Creek watershed in Canada using the hydrological modeling framework Raven, one climate scenario, and 5 landcover scenarios. The authors find changes in snowmelt seasonality, peak flow, and annual flow yield and conclude that the combined impacts of climate and landcover changes offset changes for flood events with return periods shorter than 25 years. They also find that rainfall becomes a more important influencing factor of peak flows under climate change.
General
I think that this contribution tackles a very important question, i.e. what is the join influence of climate and landcover change on hydrological signatures. However, similarly to the existing literature on the topic, it does not go beyond a case study. While the case study is carefully done and changes in different streamflow signature explained in detail for the one watershed under consideration, the generalizability of results is limited given that existing studies showcase the large variability of hydrologic responses to both climate and landcover changes and their interplay. In addition to not being generalizable to other regions, the results are also quite predictable given the existing literature: they point to earlier snowmelt, earlier flood peaks and an increasing influence of precipitation as we move into the future. While I do not see how the current study advances our knowledge related to future changes in streamflow signatures and the interplay between climate and landcover influences beyond the study region, I acknowledge the detailed and well-presented results for the case study watershed.
Other major comments
1. I find the methods descriptions detailed but rather superficial. That is, while the most important steps of the modeling framework are named, many methodological specificities remain unclear. A few examples:
- What is the temporal resolution of the streamflow data used for the analysis? (p.4, l. 98)
- Do the percentage changes in forest cover refer to the entire catchment area or just the forested catchment area (the latter would be more logical in my opinion)? (p.7, l.124-125)
- How were precipitation and temperature interpolated from station data to areal data? (p.7, l. 141)
- Which algorithm was used to estimate the full snowpack energy balance? (p.7, l.144)
- How was the historical streamflow record adjusted for storage changes in Greyback Lake? (p.8, l.152)
2. The climate impact assessment relies on one climate scenario (i.e. GCM and emission scenario combination) only, neglecting uncertainties related to emission scenario and GCM choice. While this limitation is acknowledged in the discussion section, I find that it could be overcome relatively easily by running the model for a few more climate scenarios. Furthermore, the model used for the analysis should be better contextualized within the sample of existing models (see Section 4.4.) by comparing its temperature and precipitation changes to those of other existing models.
3. The authors use a weather generator on the climate simulations to increase sample size (Section 2.2.2.3), which is per-se a good thing. However, it is unclear why these simulations are limited to 100-years given that the focus is among other variables on extreme events, which requires larger sample sizes to separate signal from noise.
Minor comments
- Use superscripts for units such as km2 and m3/s
- The discussion talks quite a bit about risk (Section 4.3). However, the authors do just look at changes in hazard while changes in vulnerability and exposure are not assessed. To avoid confusion, I would therefore use more specific terminology.
Citation: https://doi.org/10.5194/hess-2023-248-RC1
Russell S. Smith et al.
Russell S. Smith et al.
Viewed
HTML | XML | Total | Supplement | BibTeX | EndNote | |
---|---|---|---|---|---|---|
178 | 49 | 4 | 231 | 11 | 1 | 0 |
- HTML: 178
- PDF: 49
- XML: 4
- Total: 231
- Supplement: 11
- BibTeX: 1
- EndNote: 0
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1