Parameter Uncertainty of a Snowmelt Runoff Model and Its Impact on Future Projections of Snowmelt Runoff in a Data-Scarce Deglaciating River Basin
Round 1
Reviewer 1 Report
Dear authors
With great interest I read your article about the uncertainties of snow melt models and their future projections in glacier dominated areas.
The article needs only a few small additions, which should not be missing in this important topic.
51 - 62
Here you only mention the two "extremes", energy budget methods and temperature index methods. For the sake of completeness, however, the methods described in Magnusson et al. (2014 and 2017) should also be mentioned (assimilation of snow depth data).
97 - 102
GLUE: this short description is not sufficient, especially since GLUE is an integral part of this article. So: really explain in detail, back it up with literature. I will give you just one example: Saltelli et al. (2000) have written a wonderful book on exactly this subject (but recent articles which have used GLUE must also be cited).
151
80 - 82°N cannot be correct
179 - 180
Explain the interpolation method thin plate spline approach in a sentence (+ one citation)
287 - 291
As in the introductory chapter on the subject, GLUE must be explained much more extensively here. Detailed descriptions can be found in Sensitivity analysis in model calibration: GSA-GLUE approach (Ratto et al. 2001).
529
Y axis: T [°C] (instead of degree); P [mm]; snow covered area [%]
530
Period 2003 - 2012 in parentheses
552
same as in Fig. 2 (line 529)
I like the topic of your article very much and I am confident that this publication will receive a positive echo with the above additions.
Best regards
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
Review of manuscript ID water-630465: Parameter uncertainty of a Snowmelt Runoff Model and its Impact on Future Projections of Snowmelt Runoff in a Data-scarce Deglaciating River Basin by Xiang et al.
This study aims to investigate the sources of uncertainty in runoff modeling for a basin in China. A large amount of data and models are used, and the authors do a good job of summarizing the different possible uncertainties. I only have some minor suggestions and comments for the manuscript (outlined below).
Minor comments
L12: no space after “glacier-”
L30: Reads a bit odd. I would suggest changing making three points: “The results show that (1) the strategy with a division of one or two sub-period(s) in a hydrological year is more appropriate for SRM calibration, and is also more rational for hydrological climate change impact assessment; (2) the multi-year calibration strategy is more stable; and (3) the future runoff projection contains a large amount of uncertainty, among which parameter uncertainty plays a significant role.”
L32-33: I would suggest changing to: “The projections also indicate that the onset of snowmelt runoff will likely shift to earlier in the year”
L33: “of the” → “over the”
L40: I would suggest changing to: “In the coming decades, temperatures are expected to increase worldwide due to a changing climate” or similar
L41: delete “the”
L44: change to: “[…] to how climate change impacts snow”
L51: those → these
L53: and → and/or
L55: The energy fluxes are not just within the snowpack, they are mostly interacting with the surface
L57-62: Would maybe be good to mention that although Pdd models are more practical, they are often less accurate than full energy balance models. In addition, the skill of Pdd models will likely decrease in the future due to changes in the energy balance which is not a direct result of temperature (e.g. changes in albedo). The degree day factor has been shown to change over time scales of a decade or even over a single melt season (e.g. Bougamont el al, (2007),Huss et al (2009),van den Broeke et al (2010)) . If you don’t want to add this to the introduction, maybe good to mention in the discussion (L464-482)
L63-64: References?
L133: add parenthesis: “(i.e. yearly […] calibration).”
L141-145: This is a matter of taste, but I would remove this section. It isn’t necessary.
L159: I know you can see it on the figure, but I think you should consider writing in the text how far away the Hotan station is.
L199: A common mistake, but GCM stands for General Circulation Model
L199: “simulations from the phase 5 [..]” → “simulations from phase 5 of the [..]”
L211: I would suggest also adding a table with what models you use. Then you can also cite the group that created the simulations in the table (which is always nice to do considering you use their data).
L258-9: Any references for the Thiessen Polygon Method and the Inverse Distance Weighted method?
L267-274: I had a look at the different method, and I couldn’t see any mention of a topographic correction? Is that included in this method? And if not, won’t that introduce fairly big biases considering the large elevation range of your catchment?
L278: do you mean impact of temperature AND precipitation?
L356-358: The PUCI of the multi-year runs is only slightly higher than for the yearly run – is this really enough of a difference to say the multi-year runs are clearly better?
L374: the temperature increase is over which area? The catchment or the whole GCM domain?
L374-379: the presented numbers seem way too precise considering the uncertainties you must be working with in the model. Stick to one (or zero) numbers after the decimal points
L384: space between “2- and”
L366-367: “sources”, not “resources. And do you have any ideas what the other uncertainty sources could be?
L390-391: “first occurence” → “onset”
L412: “highly” → “high”
L444 & L503-4: “first time” → “onset”, delete “occurence”
L464-482: See earlier comment about degree day factors. Have there been any investigation as to whether they will be the same in the future for china?
Figure 1: The figure in the corner is missing a dot showing the location.
Figure 2: Mention in the figure caption where the data is from, and that the temperature is a point observation while the others are a mean over the area. Change temperature y-axis to write degrees C. The precipitation I would also clarify as mm w.eq.
Figure 5: I think scatter plots would give a more clear comparison and make it easier for the reader to assess the fit. Or maybe add some additional st
Fig 7: Add a b c d to the figure and explain the label for each. At the moment the SCA figures are barely described
Table 3: These numbers also seem way too precise – is there are good reason for this? Otherwise, maybe stick to 2 significant digits.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
