Study on Runoff Simulation of the Source Region of the Yellow River and the Inland Arid Source Region Based on the Variable Infiltration Capacity Model

Round 1

Reviewer 1 Report

Review of “Comparative Study on the Relationship Between Rainfall and Runoff in the Source Region of the Yellow River and the Inland Arid Source Region” by Wang et al. Wang et al. use the updated version of VIC models to simulate runoff of four rivers related to the Yellow River, of which three from the source region and one from the inland arid region. The simulation results appear to be largely consistent with observed runoff, with the relative errors of smaller than 10%. The authors then show the model sensitivity to a small group of model parameters and the simulated runoff response to temperature and precipitation perturbations. The study is clearly written and provides some useful information for VIC model applications as a case study in Northwest China. However, I suggest some major points be addressed before the paper is considered for publication, as follows. Major comments 1. Paper structure I feel the main results of this paper are not closely linked. As I read from the title I would expect a thorough analysis of the relationship between climate forcings and runoff of these rivers. However, in the first part the authors focus too much on parameter calibration and sensitivity (which can actually be put in the supplementary). The parameter sensitivity is totally independent of the second part, the climate perturbation experiments. Please modify the title and reorganize the paper to avoid confusion. Please also add the rationale for the chosen rivers. 2. Climate change scenarios The authors use perturbations in (surface air?) temperature (by +0.5, +1, +1.5) and precipitation (by -10%, -5%, +5%, +10%) to construct what they assume as future climate scenarios. This very simple assumption can be problematic. First, the climate change is not a uniform pattern. There are surely spatial patterns of anomalies with different magnitudes or even opposite signs. Besides, the ecosystem interacts with climate change should not be ignored. The greening or browning of the land cover can also potentially affect simulated runoff. Please either clarify your definition and state these scenarios are actually climate perturbations, or use more realistic scenarios (e.g. CMIP model ensembles in RCP scenarios). Other comments: L98. There is a small reservoir (Huaitou Tala) that can affect the runoff of Balegen river. Can it explain the overestimated magnitude of change in streamflow in the simulation (Fig. 7d)? L122, Figs. 3&4. The model resolution is relatively coarse (e.g. compare with finer-resolution of vegetation distribution). It means the model grids can barely capture the shape of the four rivers simulated in this study. Please add a short description on this issue and provide more evidence that such a resolution can be applied here. Sec 3.2.2. The model input files only includes vegetation types? Is there any seasonal cycle signals (e.g. change of classifications for different seasons; interannual variability)? Fig. 3&4. You averaged the vegetation classification within a model grid? L208. Please define index i (time step?) and explain more about the NSE used here. Simply based on your description “the degree of fitting between…” vs. “the deviation between…”, I cannot tell the difference between NSE and RE. Sec 4.1 & Table 4. The justification of why these parameters are used are is missing. Why do you only emphasize on these parameters only? L274. If so, please determine the optimal parameters and have a discussion on how future studies can benefit from such a selection. Fig. 8. I am not sure why you used the polar axis. What’s the meaning of the vertical axis (between -0.2 and 0.2, 0??)? Why not just use a x-y axis? L303. I would guess it’s due to the reservoir… Figs. 9&10. The two figures are duplicate. The same values are shown twice. Sec 5&6. Please add discussion on what is the implication of your results and how it can help water source management in the Yellow river basins. You are submitting your paper to Sustainability, and this main scope should be discussed to some degrees here. Refs. The refs for the model are quite outdated (the most recent one is in 2001). Is there any model development between 2001 and now? I can find a lot of publications in Chinese journals or as dissertations of Chinese Universities which I don't have access to read. Are they actually written in Chinese?

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript title: Comparative Study on the Relationship Between Rainfall anf Runoff in the Source Region of the Yellow River and the Inland Arid Source Region. Makes a good comparison of rain and runoff in areas with climatic differences, taking into account rainfall, soil type, vegetation, etc. In which have it come to some good conclusions. Although I think that evapotranspiration according to the type of soil is interesting and is not reflected, as well as the relationship between soil, slope and infiltration, it is not entirely clear. 

Also I have some comments in the pdf document attached below. 

Generally format details.

In conclusion, I recommend this article for publication after correcting some details (pdf document)

Comments for author File: Comments.pdf

Author Response

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Round 2

Reviewer 1 Report

I appreciate the authors’ efforts in addressing my previous comments. I think the manuscript has been improved significantly. I only have a few minor more comments.

1. The authors can consider to change all “climate change scenario” to “climate perturbation experiments”

2. I meant the updated refs for the VIC model. Did you still use the same model version as in the 2001 paper?

3. English proofreading is needed.

Author Response

请参阅附件。

Author Response File: Author Response.pdf