Constraining Flood Forecasting Uncertainties through Streamflow Data Assimilation in the Tropical Andes of Peru: Case of the Vilcanota River Basin
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this manuscript, assessed a sub-daily flood forecast system in a basin of the Peruvian Tropical Andes using two sequential data assimilation algorithms called the Ensemble Kalman Filter (EnKF) and the Particle Filter (PF). This work provides a reference for the application of streamflow data assimilation in Peru and the Andean basin, and supports the development of more accurate climate services in Peru through integrated hydrological forecasting.The results of the study have certain guiding significance for improving Peruvian climate service, but there are many issues that need to be considered. The specific ones are as follows:
1. The introduction lacks a description of the current status of data assimilation research, and does not clearly explain the contribution of previous research to the field of change.
2. Is there a basis for the statistical indicator equation in the article table? If so, cite it.
3. In Section 2.4, the explanation of the parameter εp in Equation (3) is lacking, please explain its meaning.
4. In Section 2.5, it is debatable whether it is reasonable to use the updated status of the GR4H model as a baseline for 1- to 24-hour flow forecasts.
5. In the fifth paragraph of Section 3.3, please provide reasons why GSMaP-NRT '+EnKF was chosen to illustrate the contrast of observed and forecasted discharge times series during February and March 2022 at the Pisac stream gauge station.
6. How can the author verify the rationality of the chosen model?
7. Figure 8 only shows the curve comparison of other models, but lacks the information of the selected GSMaP-NRT '+EnKF, which is not enough to reflect the advantages of the selected model.
8. It is recommended to summarize the innovations of this article in the conclusion section.
9. The article is difficult to read, the logic of the sentence is not clear enough, and it needs to be condensed. And there are many details that need to be carefully examined.
Author Response
Dear reviewer.
Each of your observations is answered point by point in the attached document.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe topic of the present paper Constraining flood forecasting uncertainties through streamflow data assimilation in the Tropical Andes of Peru: Case of the Vilcanota River Basin is very interesting for readers, flood modeling and forecasting being key to managing and preparing for extreme flood events.
The present manuscript aims to assess a sub-daily flood forecast system in a basin of the Peruvian Tropical Andes using two sequential data assimilation algorithms called the Ensemble Kalman Filter and the Particle Filter.
The experimental results indicated the potential to improve sub-daily streamflow forecast in the Vilcanota River basin by assimilating real-time observed discharges at the basin outlet. This work establishes the basis for hydrological streamflow predictions in an Andean basin of Peru.
The authors highlighted the necessity to improve hydrometeorological observations for a better understating of rainfall-runoff transformation and streamflow predictions in the Tropical Andes.
Finally, I conclude that:
- the introduction provides sufficient background and includes relevant references;
- the work design is well described;
- the reference list is large and recently;
- the text is clear and easy to read;
- the manuscript is well written, and the text is easy to read.
Author Response
Dear reviewer.
Each of your observations is answered point by point in the attached document.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Author(s)
However, the present manuscript shows a promising paper, but in its current state, a definitive decision regarding approval or rejection cannot be made until the necessary amendments are undertaken to enhance the clarity of the experimental aspects and results in the manuscript. All the required amendments are listed below:
The abstract section needs an in-depth revision of each paragraph, eliminating any extra sentences, and giving greater priority to effectively presenting the practical results derived from the experiment.
Given the numerous abbreviations used in the research text, it is essential to include a list of abbreviations.
Introduction: It's worth mentioning that some short sentences (not exceeding two lines) ended with two or three references, which is logically inconsistent. It is advisable to review these sentences and write the necessary sources as indicated by the context.
The intended meaning of these sentences must be explained in more detail and more precisely, with reasons given:
- “Hydrological forecasting aims to predict the system response from different input changes”
- “In that sense, Data Assimilation (DA) seeks the combinations of observation and model errors through the update of model states [23].”
The following sentence is very general, needs clarification and more details: “Despite the advancements in streamflow DA worldwide in the last decade, the number of ensemble flood forecasting in South America is still emerging as highlighted by [37,38]”
At least one example should be given for each type of error mentioned in the following sentence: “Forecasting uncertainties may evolve due to measurement errors [17,18], input errors [19], structural errors [20], parameter estimation errors 49 [21], and simulation errors [22]”
The following paragraph should provide a more thorough explanation of each mentioned point, as the previous explanation is lacking in detail. Additionally, it is advisable to enhance the introduction by incorporating a “SmartArt graphic” diagram that encompasses these three measurements: a, b, and c.: “To deal with that point, the following main steps are identified: a) design of the DA experiment scheme, b) quantification of model errors in the hydrological system, and c) application of the chosen DA algorithms into the Open Loop (OL) model.”
In the following paragraph, clear and specific reasons for conducting DA only in these areas of the South American continent should be stated: “Most DA experiments have been applied in snow-dominated basins in the extra-tropical Andes using observed discharges [38,39] and remote sensing of snow cover [40]; or incorporating satellite altimetry in the great Amazon basin [41–44].”
The last paragraph of the introduction does not explain the aim of the manuscript in an acceptable manner. Therefore, it needs to be modified and reformulated to better reflect the purpose of the study.
It is not permissible to speak in the form of pronouns. Therefore, any paragraph that includes the use of pronouns such as We, I, and others must be modified.
According to what was mentioned in the aim of the research, the model used is “GR4H”. However, the introduction does not include any introductory explanation of this model, nor the history of its creation, nor its advantages or disadvantages, nor the degree of convergence of the results of previous studies that used this model to real data. The introduction must be completely reformulated and a sufficient special paragraph about the model used must be added.
Materials and Method
Figure 2 is not clear. It needs to be redrawn more clearly and to clarify the data during the mentioned years. Why was the period 1981-2010 chosen? What about subsequent years until 2023? Why was it not included in Figure 2?
This sentence needs a deeper clarification and more detail with regard to the current study, and it is not enough to simply mention its source: “The process of merging SPPs and rain gauge information for the Vilcanota basin (IMERG-E’ and GSMaP-NRT’) is described in detail by [45]”
Results and Discussion
The results section should be combined with the discussion section and the discussion of each paragraph should be clarified separately. In general, the explanation provided for the results is brief and requires adding many missing explanations to explain the results obtained in a better way. The discussion section should be rewritten appropriately.
The manuscript must include an additional section to illustrate the future vision of the objectives of this study at the level of Peru country, the Latin American continent, and the world, as modeling the results without a future conclusion will be of very limited benefit.
Conclusions:
The section of conclusions does not include any clear numerical measurements of the results obtained nor how close the results are to real measurements. In addition, it contains sections that are not necessary, such as future studies and the improvements this manuscript will provide in terms of rainwater, forecasts, etc. This section should be completely rewritten so that it addresses only the conclusions drawn from the research in sufficient detail.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
Dear reviewer.
Each of your observations is answered point by point in the attached document.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have made detailed revisions to the issues raised. The manuscript is recommended for acceptance.
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Author(s)
The revised manuscript is good
All the best
