Morphological Patterns and Drivers of Urban Growth on Africa’s Wetland Landscapes: Insights from the Densu Delta Ramsar Site, Ghana
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear authors,
I read your manuscript with interest. It is generally logically structured and reasoned. I would like you to strengthen its following elements:
1) How do your results look from a global perspective? This primarily concerns the comparison of the results obtained with other regions of the planet that face the same problems, primarily within wetlands. This will be a big plus for an article in an international journal.
2) The manuscript does not contain any information about the limitations and uncertainties of the study.
3) Some maps do not have a scale.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
Comment 1
How do your results look from a global perspective? This primarily concerns the comparison of the results obtained with other regions of the planet that face the same problems, primarily within wetlands. This will be a big plus for an article in an international journal.
Response 1:
Findings from similar studies elsewhere around the globe have been incorporated into the Discussion to enrich the quality of the paper as suggested.
Comment 2:
The manuscript does not contain any information about the limitations and uncertainties of the study.
Response 2:
A paragraph on the limitations of the study has been included at the end of the Conclusion section.
Comment 3:
Some maps do not have a scale.
Response 3:
Scales have been inserted into the affected maps.
Reviewer 2 Report
Comments and Suggestions for Authors… urban growth in Africa’s wetland landscapes… Sustainability-3057289
Reviewer comments:
This paper describes the growth of urban settlement and related development adjacent to Accra over recent years and points out its impact on a designated wetland area (RAMSAR site). Data obtained from a series of satellite images and ground truthing has been meticulously analysed, providing a detailed and convincing account of unplanned development which is seen to follow a combination of 3 established models of peri-urban expansion. The account is well written, logically presented and easy to read. Conclusions are supported by appropriate and largely well explained statistical analyses.
The implications of this study are far-reaching, beyond the target location in Ghana, as similar poorly controlled urban expansion has taken place in sub-Saharan Africa and throughout the developing world. This is a matter of concern in terms of detriment to the environment and biodiversity, as well as its impact on human welfare. Based on interview accounts with officials from local environmental protection agencies, the authors point to failures of development control due to political interference, pressure from short-term interests and inadequate resourcing to manage the planning process. The quote in lines 631-2 is particularly telling. There are echoes here in the UK, given the progressive reduction in resourcing and influence of official agencies for environmental protection over recent years.
In my view, it is important that this study should be published, as it may act as a signpost to those responsible for managing the pressures of population growth and urban expansion, especially in the developing world. I wish the authors every success in their attempts to create a more rational framework for sustainable development in the Densu Delta and beyond.
I would ask the authors to address the following queries regarding their regression analysis and to amend the text accordingly.
Line 370: How are ACC and WET both used in a Pearson correlation, given that ACC is a continuous variable but WET is discontinuous? – please explain.
Why does WET appear in the predictive regression equations for CHANGE 1, 2, 3 (4a, 4b, 4c) and ABCR 12, 17, 22 (6a, 6b, 6c), given that WET had apparently been dropped in favour of ACC2 due to autocorrelation (stated in line 372)? This removal of WET appears to be a general statement, applying to, at least the OLS regression models of equ. 4a,b,c – please explain.
A few minor text corrections:
95 The present study…
241 “eastern” should be “western”
Fig 3 map: authors should mark position of Weija dam. Positions of names of some Localities on map could be adjusted to avoid over-writing other features. The name is Grefi on map but Glefe in text.
440 “purposively” – was “purposely” intended? I suggest to cut the word (it is redundant).
470 2,77.3 should be 277.3
652 “of” should be “on”
Author Response
Comment 1:
Line 370: How are ACC and WET both used in a Pearson correlation, given that ACC is a continuous variable but WET is discontinuous? – please explain.
Response 1:
WET shouldn’t have been included in the Pearson correlation analysis. Error has been corrected.
Comment 2:
Why does WET appear in the predictive regression equations for CHANGE 1, 2, 3 (4a, 4b, 4c) and ABCR 12, 17, 22 (6a, 6b, 6c), given that WET had apparently been dropped in favour of ACC2 due to autocorrelation (stated in line 372)? This removal of WET appears to be a general statement, applying to, at least the OLS regression models of equ. 4a,b,c – please explain.
Response 2:
WET has been excluded from the equations.
Comment 3:
A few minor text corrections:
- 95 The present study…
- 241 “eastern” should be “western”
Response 3:
Corrections have been made.
Comment 4:
Fig 3 map:
- authors should mark position of Weija dam.
- Positions of names of some Localities on map could be adjusted to avoid over-writing other features.
- The name is Grefi on map but Glefe in text.
Response 4:
A new map has been prepared to incorporate the suggestions.
Comment 5:
440 “purposively” – was “purposely” intended? I suggest to cut the word (it is redundant).
Response 5:
Correction has been made.
Comment 6:
470 2,77.3 should be 277.3
Response 6:
Correction has been made.
Comment 7:
652 “of” should be “on”
Response 7:
Correction has been made.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors carried out an integrated assessment of urbanization patterns using remote sensing, field interviews and robust statistical methods. Indeed, the data analysis was adequate and the diagnosis of the premises was satisfactory. However, despite not identifying any technical problems, I found the length of the article to be disproportionate to the proposed objectives. Theoretical contextualization must be strongly reduced. In addition, I understand that the descriptive characterization of the area of urbanization patterns is important, but I strongly suggest that the authors synthesize the text as much as possible and focus on the main results (Section 4.5). Much of the conceptual contextualization (Sections 2 and 3), Figures and Tables can be transferred to the Supplementary Material.
Specific comments:
Abstract
L17: The authors could highlight which regression methods were used.
M&M
L234-241 and Figure 3: The authors have described the study area in a very local way. I suggest that the authors indicate the country where the study was carried out and, in Figure 3, highlight the location of the study area in relation to the continent (or at least neighboring countries).
L270: Is there any predominant industrial activity that should be noted?
L276: Typo(.it). Please, proofread the entire manuscript for typos.
L290-295: The method of supervised classification of land use and land cover classes is not trivial and must be properly evaluated before the data can be used for statistical analysis. How did the authors assess the accuracy of the classification method?
Figuras 4 e 5: I believe that the description of the methods is sufficient and that these figures can be included as Supplementary Material. The article has 13 figures. The authors should define which figures are fundamental to the understanding of the study and which can be moved to Supplementary Material.
L363-382: The method used is sound and the diagnosis of the assumptions was adequate. I only suggest that the authors make the results of other tests/graphs besides Moran's I available as Supplementary Material. Table 3 could even be transferred to the Supplementary Material.
Results
The Results section should be summarized. The authors have focused too much on the descriptive evaluation of the urbanization pattern which, although important for the context of the study, is not the main objective. The main focus should be on section 4.5.
In addition, as mentioned earlier, the article has many figures and this can be a bit tiring. I suggest that, when possible, the authors combine two graphs into a single figure to optimize the description of the results. For example, Figure 7 and 8.
Discussion
The discussion is disproportionate to the amount of results presented. I suggest that the authors take a deeper approach to the literature and expand this section of the manuscript to discuss:
1. Are the urban growth patterns observed in this study comparable with the growth observed on a national scale? Or with other Ramsar sites located in Africa or on other continents? The data was discussed on a local level. In this context, the authors should refine the literature review to elevate the discussion to a national and global context.
2. How does unrestrained urban growth impact natural resources, including aquatic ecosystems, which are fundamental to the characterization of a Ramsar site? Are there any studies published in Ghana or neighbouring countries on the relationship between urbanization and pollution or risks to human health?
3. The drivers of urbanization and institutional failures have been identified. Can the authors propose sustainable solutions to mitigate the negative environmental impacts of urban growth?
In addition, I suggest that the authors include a paragraph highlighting the limitations and strengths of this study.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThank you for revising the manuscript.
Comments on the Quality of English LanguageMinor editing of English language required
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors made substantial revisions that improved the quality of the manuscript. I recommend acceptance of the manuscript in its present form.
