Utility of Remotely Sensed Evapotranspiration Products to Assess an Improved Model Structure

Round 1

Reviewer 1 Report

The authors improved manuscript accordingly. 1.  The introduction section can be updated using newly published relevant studies. 2.  The innovation of the paper should be further characterized. 3.   In the discussion part, your results should be compared to other previous researches and have a deep discussion 

Author Response

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Reviewer 2 Report

The manuscript may be accepted for publication.

Author Response

Thanks for your time and efforts.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Recommendation: Interesting paper. My advice would be to ask for a minor revision of the manuscript.

 

Comments:

The manuscript entitled “Utility of remotely sensed evapotranspiration products on assessing an improved model structure” presents interesting work on studying the utility of remotely sensed evapotranspiration products to represent improved model predictions by structural improvements. Overall, it is a well-written paper.

There are some minor issues the authors might address. The Kling-Gupta Efficiency was heavily used in the paper but was only introduced in the method section. Instead, if this is very important, it should be introduced in the introduction.

 

The title of “3. Result” should be changed to “Results and Discussion”.

 

Conclusion: there is no need to introduce the limitation or background in the conclusion part. Just list the most important findings of this study. I would suggest to expand the second paragraph of the conclusion and add some key points from the first paragraph to make it a whole paragraph.

Author Response

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Reviewer 2 Report

I have many concerns regarding the appropriateness of this manuscript for publication in this journal. The contribution of this research in the literature is very confusing and unclear. Also, the authors should carefully and thoroughly revise the manuscript in order to improve the English language and correct any grammatical errors.

 

The authors said that “Streamflow and watershed-level RS-ET were used to calibrate SWAT and RSWAT and the optimal simulations from two models were compared at both the watershed and subwatershed levels. SWAT and RSWAT produced similar streamflow and ET at the watershed level with similar performance metrics, but low-flow conditions simulated by RSWAT were substantially closer to observed flow relative to SWAT”.

This statement is very confusing, as it is not clear in the manuscript which are the inputs and the outputs of the modeling simulation. Also, the authors used as performance metrics the Kling-Gupta Efficiency (KGE) index. Based on KGE, in this study, the comparison results are close to 0.5 and in some cases lower than this value. However, based on literature [Rogelis et al (2016)], the studied simulation approach seems to be inadequate or “poor” for 0.5 > KGE > 0. This evidence is also obvious concerning the peak values of the simulation (see figure 4a). Authors should use more statistical metrics (appropriate for streamflow simulations) in order to compare model outputs. For instance:  the Nash-Sutcliffe Efficiency (NSE), the RSR, and the PBias (%).  

Author Response

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Reviewer 3 Report

The manuscript aims to evaluate the improvements brought out by changes in hydrologic model structure using remotely sensed evapotranspiration (ET). The aim of the manuscript is a good one and the overall manuscript is succinctly written.

However, the results obtained from this manuscript are already well established through several papers published in last 2-3 years. Whenever a change is made in a model, the variable which will be directly affected by the change has to be evaluated. In that sense, changing the soil moisture (SM) module is expected to bring direct effect in the related variables i.e. SM and ET. May be for some other catchments, in which the runoff is strongly influenced by SM, the effect of change in SM module may be reflected in the runoff/stream flow simulated by the model. Hence, the conclusions from this study are on the expected lines.

Few comments about the manuscript are given below:

Recent studies have related to modelling have focussed on spatially distributed calibration when using RS-ET. However, in this study, a lumped calibration has been performed which may reduce the impact of having RS-ET at much higher spatial resolution. Hence, it is suggested that the authors attempt a spatially distributed calibration at least at HRU level. The authors are referred a  recent study  (Yang et al., 2020, https://doi.org/10.1016/j.jhydrol.2020.125730) which explains the advantages of a spatially distributed calibration.

Also, the accuracy of the RS-ET and the model simulated ET is not clear. Any results pertaining to ground validation of RS-ET and model simulated ET must be presented along with metrics such as RMSE (in both absolute units such as mm/day and as percentage of observed ET) and bias. Without this, it is difficult to assess the improvements obtained from the model.

In addition, the model performance should be evaluated for at least one year period (e.g. for the year 2015) without using calibration data (both stream flow and ET). This is again important to gain confidence in the model simulations.

 

Author Response

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Reviewer 4 Report

1. Draw a flowchart from your work flow that briefly shows the process and in the Discussion section. 2. Compare your results with the results of other researchers. 3. The literature review part may be further improve.  4. In abstract and conclusion, authors need to add some numerical results. 5. Description of the figures should be more complete 6. Improve the English.   7. The conclusion should include more details.  8. Please improve the Conclusion section, this section need to more details and more explain. 9. Please refer to new paper about this field.

Author Response

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Round 2

Reviewer 2 Report

The authors were not able to positively address the crucial comment regarding the performance metrics which is very important for a journal publication, especially to a high impact journal such as Sustainability. Moreover, the authors deny using more statistical metrics (appropriate for streamflow simulations) in order to compare model outputs.

Reviewer 4 Report

The authors improved their manuscript according to comments.
Conclusion section still needs an improvement.
Please compare the results by others researches results.