Inner Niger Delta Inundation Extent (2010–2022) Based on Landsat Imagery and the Google Earth Engine

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have done good work and they may increase the quality of figures by providing north arrow and scale. Authors may consider this article for the mentioned comment. The authors may redefine the figure 7 as it is not understandable and creating confusion in terms of October and November.

Comments on the Quality of English Language

The quality is good and may be improved at some parts particularly in Discussion..

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

Authors combined the Google earth engine platform to do the long-term monitoring of inundation in the inner niger delat. Landsat imagery series were utilized and processed at GEE platform. However, although authors introduced several indices to extract waterbody information. Methods are still traditional. Although you selected several indices to help extract waterbody. However, waterbody extraction has been widely used in several studies. You used supervised classification method to extract waterbody information and map them to analyze the total areas change. Generally, this manuscript had done a plenty of job, however, it lacks outstanding ideas or proposed newly or modified methods to extract waterbody information. Especially, the abstract part, discussion part and result part is not sufficient. Abstract you should highlight the key improvement in your manscript, however, existing version is too general, which described what you have done and the change results of your work. 

Results part, i was confused about the waterbody extraction result. in the northwestern part, the water body displayed too strange, is these part all belonged to waterbody? In addition, at methods part, you don't decipt the processing step about how to remove cloud or how to select the satisfied images. 

At the discussion part, authors should had better introduce the waterbody extraction accuracy of different methods or how these selected indices influence the waterbody extraction accuracy. Lastly, based on your results, what detailed suggestions could be formed to local government. Just telling them the inundation range? or what measurements they should take?

Suggest authors to think these questions deeply.

In addition, English writing is not good. There existed numerous grammar mistakes. Please used extensive english modification before submitting to other journals.

Line 49: means should be 'mean'

Line 50: different remote sensing data should be different remote sensing datasets;

Comments on the Quality of English Language

English language should be under extensive modification.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

The paper presented an application of flood inundation mapping using remote sensing data in GEE

The manuscript require small modification as given below:

Please explain the Kappa coefficient and overall accuracy computation procedure in the methodology part.

In the conclusion part, explain the application of the methodology suggested for decision making.

 

 

Comments on the Quality of English Language

No specific comments

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

In order to improve the readability of the paper, some comments are given below.

Summary

Line 19: Please check the double space after the period "2010 and 2022.  The ..."

Introduction

Line 47: Please add a full stop after etc. One for the abbreviation, one for the end of the sentence.

Line 60:  "Most studies" or "Most studies cited"? Please check whether the sentence refers to the sentence reported on lines 55-59 using "most of the cited studies".

Line 64 Please replace "but not limited…" with "among several". 

Line 84 Please try to avoid the use of "I, we..." in scientific papers, preferring instead the third person or impersonal forms.

Lines 94 and 95 same comment. Avoid the use of I, We. Check this throughout the paper.

Materials and Methods

Line 121: please check and consider reporting "the Office du Niger" (instead of "The Office of Niger") as done in Figure 1 and Line 323. If the proper name is "The Office du Niger", use the same as in Figure 1. 

Line 151: try to avoid the use of "We" and use the third or impersonal forms. Check this throughout the paper.

Table 1: please try to quote the table more coherently to make it easier for the reader to understand. On line 84 the description of this table is "....number of tested indices" while on lines 187 -189 "Table 1 presents the different primary bands (LS bands) and secondary bands(...)" as reported in the caption. 

Line 239: Please check that the paragraphs are aligned according to the template.

Line 236: Cite the figure in the same way. Previously, Figure X was cited in the text and (Fig. X) was used when the reference was reported in parentheses. In this line, according to the usage in the previous section, Fig. 4 needs to be replaced with Figure 4. This is a minor comment, but please use the same way to cite them to make it easier for the reader to understand.  (Check this issue throughout the paper).

Line 249: Please check that the paragraphs are aligned according to the template.

Results

Line 267: please check the sentence a dot is probably reported as a typo or a capital letter is missing “for any given year. which confirmed the method’s consistency in detecting flood extent.”

Line 294: Please rephrase the sentence "A more detailed investigation shows..." as it is not clear what the more detailed investigation is. 

Line 290: Please check whether the number explained is 6 or 7 a and if so, please replace with the correct number.

Line 297: Use the same approach to cite the figure and check if figure 7a is introduced in the text (probably on line 290 according to the previous comment).

Line 325: Check that there is a comma missing in the number 1200, according to the standard used in the paper for reporting thousands.

Line 327: Use the same approach to cite the figure

Figure 9: Please consider repeating the legend in both parts of Figure 9 on pages 13 and 14.

Discussion

Lines 352, 361, 367, 370, 377 and 386: Please avoid the use of OUR as commented on in the previous sections. Please review this issue throughout the paper.

Line 368-369: Please rephrase the sentence "thus con confirms the increasing trend in flood extent since this study examines recent years".

Line 378: please use the same approach to cite the figure

Line 392: please check if there is a comma missing in the figure 130 000 ha.

Author Response

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Reviewer 5 Report

Comments and Suggestions for Authors

 

In this study the authors investigate the interannual variation of seasonal inundation in the Inner

Niger Delta by means of Landsat Imagery and Google Earth Engine. Temporal and spatial distribution patterns of the inundation extent between 2010 and 2022 are examined and compared to other previous studies. I really appreciated this work; the purpose, methodology, results are well presented in a clear and easily understandable form. English editing is fine. The work exploits the wide availability of images from the Landsat dataset and the great potential offered by the Google Earth Engine platform.

On the other hand, I have identified some issues which in my opinion should be resolved to improve the already good quality of the work; I report them below:

·      The introduction lacks the state of the art of similar studies for the same study area, both through the use of satellite images and through empirical methods ( like Zwarts et al. 2005). From the discussion it is clear that several studies have already been carried out and the authors rightly compare their results to them. In my opinion, however, the authors should mention and describe them in the introduction, specifying which datasets and methodologies were used. Furthermore, it should also be clarified what the advantage proposed by the proposed methodology is (I imagine greater spatial and temporal resolution) both in the aims of the work at the end of the introduction and in the discussion.

·      Google Earth Engine is mentioned in the title of the work itself; precisely for this reason, it is necessary to dedicate a paragraph to it in the introduction for those who do not know it briefly describing the advantages and potential of this revolutionary platform. Furthermore, it should be clarified whether all the work, including the random forest classification and the various statistical analyses, was performed on Google Earth Engine platform or whether it was only used for some steps such as the preparation and processing of the satellite datasets and the Training Sample Collection. If other software has been used for random forest classification, it must be indicated in the text.

·      In my opinion, the order of the paragraphs in the results section is not consistent. Resulting cartography should be placed in paragraph 3.2 and the derived statistics in the following ones. Furthermore, if I'm not mistaken, the spatial resolution of this cartography is not indicated anywhere in the text. I imagine it is 30 meters like that of the Landsat imagery from which it is derived, but it should be clearly indicated in the text.​

·      Line 150: how was cloud removal performed? Please explain

·      Please add squared R and pvalue to equation of fig.5

·      Line 296 and fig. 7b is this correlation statistically significant? Please add pvalue.

·       Lines 305-315. This part must be moved to the methodology in a specific paragraph dedicated to the comparison of the results with those of this empirical methodology.

·      Line 315. I think it’s figure 8, not 7.

Author Response

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Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have addressed my concerns in this version.

Reviewer 5 Report

Comments and Suggestions for Authors

The authors made a good job of revision following the instructions and suggestions of the reviewers. In my opinion, the manuscript can be accepted in present form.