Socio-Institutional Drivers of Groundwater Contamination Hazards: The Case of On-Site Sanitation in the Bwaise Informal Settlement, Kampala, Uganda

Round 1

Reviewer 1 Report

The work of Felix et al. aproaches an interesting point, that of contributing to the development of a socio-institutional assessment framework basing on a case study of contamination by on-site sanitation in an informal settlement, investigating the key socio-institutional drivers of the hazards.

The title is relevant to the content of the paper and the abstract is written in a clear and concise manner.

As I can not see the Line number due to some technical error that is not from my end, I will simply quote the points that require attention.

-"Groundwater contamination hazards include microbial, nutrient and more recently micropollutants of emerging concern [2]–[4]."

The main groundwater hazards are those of biological nature, pathogens are more widely spread than heavy metals and other sources of polutions, especially in developing areas that have little to no industrial activity. I would like to suggest to provide further details regarding this fact as is one of the main issues in groundwater contaminations in such cases.

-" Therefore, implementation of a WSP
for the protection of groundwater in order to foster increased utilization of groundwater was explored as a specific niche activity "

Clearly state the actions of the plan in a more concise style.

"3.2. Groundwater Sample Collection and Microbial Analysis "

This part, although simplistic in contrast with the rest of the text, is well written. I would appreciate to see the same technical and easy to comprehend approach in the rest of the paper.

The paper is overall good and it will add value to the current literature. 

I propose a minor revision as the above stated.

Author Response

Responses to the reviewer 1 comments attached.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper „Socio-Institutional drivers of Groundwater Contamination Hazards: The case of On-site Sanitation in Informal Settlements in Kampala, Uganda“ presents a novel approach to analyse a risk of sanitation-related groundwater contamination in informal settlements. Integration of IWRM and transitional management (TM) approach contributes to development of risk assessment framework in poor communities. The goal of the paper is clear, the methodology is innovative and results are clearly presented.  I have two comments.

1. Authors should better explain the structure of in-depth interviews with key participants (Chapter 3.3). The concept of the interviews and key questions should be better explained in the paper. I would suggest to add the question form in supplemental materials.
2. Authors should give a clear evidences of the climate change processes impacting water resources state and condition in the chapter 4.2. They should relate these evidences with results of the previous research (through literature review) or through their own research results.
3. Suggestion for authors: please increase fonts in the figure 5.

Author Response

Responses to reviewer 2 comments attached.

Author Response File: Author Response.docx

Reviewer 3 Report

I have read the resubmitted manuscript by Twinomucunguzi et al. and despite the improvements in many sections of the manuscript like the introduction and discussion, there are some flaws that in my opinion does not suggest this paper for publication in Water.

Briefly, the conclusion reported by the authors that "The purpose of this paper was to assess the recent level of groundwater contamination by OSS in informal settlements" cannot be sustained by just 7 groundwater samples and 2 springs in 2 sampling campaigns . No major ions and trace elements were analysed, while only Escherichia Coli were scrutinized. I do expect that ammonium and or nitrate as well as chloride sulphate and DOC would increase respect to background values. Thus, in my opinion this dataset is totally insufficient to prove and quantify the spatial and temporal extent of groundwater contamination at the site.

Again the authors stated "The case study showed that over 40% of the groundwater sources were contaminated by E.coli attributed to OSS." The percentage here indicated is affected by an enormous uncertainty given the limited amount of samples that do not provide any statistical representativeness.

The results found by this study cannot be considered robust enough to be replicated in other sites given the paucity of presented data and the consequent low level of elaboration that lead to highly speculative discussion and conclusions sections.

Author Response

Response to review 3 comments attached.

Author Response File: Author Response.docx

Reviewer 4 Report

An interesting paper describing socio-institutional controls of groundwater contamination from sewage systems in informal settlements. It is well written and detailed in its coverage of the research undertaken.

I have only a few minor comments:

Abstract. Edit '..framework basing on a case..' to read 'framework based on a..'

Introduction. first para. Add 'chemicals' to the lists of pollutants.

Introduction. First para. Quote the SDG 6. Edit: '..(SDG) 6 to "ensure availability and sustainable management of water and sanitation for all". I would also change reference [5] to the UN SDG page: https://sdgs.un.org/goals/goal6 

Introduction, penultimate para on p3. Add 'Uganda' to description of location of first introducing the site.

Figure 2. Main map is not very informative, and the colour selected is too dark to allow the text to be easily read. Redesign / redraw Fig 2.

Author Response

Response to reviewer 4 comments attached.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Despite the attempt of the authors to justify the scarcity of field data and to avoid statistical representativeness.  I am still convinced that as it is now presented, this paper is not suitable for publication in Water. The main reason is due to the inability to proof the proposed concepts, namely groundwater contamination by on-site sanitation, by the lack of detailed  hydrogeological and hydrogeochemical data. I suggest the authors to submit their work to a local journal since it is not possible to extrapolate from their manuscript robust findings or concepts applicable and valid in different hydrogeological settings.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

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

The paper „A Socio-Hydrogeological Risk Assessment Framework for Sanitation-Related Groundwater Contaminants in Informal Settlements, Kampala“ presents a novel approach to analyse a risk of sanitation-related groundwater contamination in informal settlements. Integration of IWRM and transitional management (TM) approach contributes to development of risk assessment framework in poor communities. The goal of the paper is clear, the methodology is innovative and results are clearly presented.  I have several comments.

1. Authors should add the location map of the area
2. A numerous abbreviations were added in the paper. Due to clarity, authors need to add a list of abbreviations with explanation at the end of the paper.
3. An explanation of variables in the equation 1 is needed.
4. Authors should explain in more detail the implementation of risk assessment framework presented by equation 1 in their case study. This part of the paper is not clear.

Reviewer 2 Report

This work suggests a socio-hydrological assessment framework to evaluate the risk of sanitation-related groundwater and provide improvement strategies.

The objectives are clear, the introduction is very well written and informative, and the topic is critically important to be discussed. On the way toward SDG6, we lack such strategical approaches. So, I sincerely appreciate the authors' efforts and enthusiasm for conducting a study in this field.

The suggested framework seems to be comprehensive considering all the actors to whom this framework may be related. However, the biggest issue with this study is that there is no information on analyzing the "applicability" of this framework.

Authors should conduct case studies to prove that the suggested framework is efficient and effective. This is while the presented study does not report sufficient data about this matter. If the framework is not applicable, it could not be trusted and executed.

Also, the number of respondents for the key informant interviews (34 people) is pretty small and may lead the produce biased results. I invite the authors to consider a higher number of interviewees (at least 100) preferably from different countries.

The authors briefly discussed the work conducted by Werz and Hötzl (2007) but they surprisingly did not apply the presented equations to the study. Qualifying the framework is very important which is being missed.

I also invite the authors to consider reviewing indexes that are designed to evaluate the sustainability of a sanitation system. Here is a list of some publications in this regard, sorted based on publishing time.

2020: https://doi.org/10.3390/su12176937
2015: https://doi.org/10.3390/su71114537
2015: https://doi.org/10.13140/RG.2.1.2194.5763
1999: https://doi.org/10.2166/wst.1999.0244

I invite the authors to discuss these indexes. How your study can make a contribution to the sustainability of sanitation-related groundwater in comparison with these indexes.

In contrast with the title of the study, the authors did not aim for any detailed groundwater contaminants. They are suggesting a framework which is generally considering technical, social, and economic aspects. I suggest revising the title. Also, please clearly define the term "sanitation-related groundwater." Does it refer to a groundwater source that is contaminated with sanitary matters?

I suggest the authors consider the suggestions cited above and proceed with a substantial revision to resolve the flaws.

Reviewer 3 Report

The paper presented by Twinomucunguzi et al. is a manuscript that deals with the description of an analytical framework aimed at preventing sewage groundwater contamination in informal settlements. The novelty of the study is not clear since it is relying on a previous paper (published by the same authors group) that has developed the general framework of the Transition Management Attributes towards Implementation of Water Safety Plans.

Twinomucunguzi, F.R.B.; Nyenje, P.M.; Kulabako, R.N.; Semiyaga, S.; Foppen, J.W.; Kansiime, F. Reducing Groundwater Contamination from On-Site Sanitation in Peri-Urban Sub-Saharan Africa: Reviewing Transition Management Attributes towards Implementation of Water Safety Plans. Sustainability 2020, 12, 4210. https://doi.org/10.3390/su12104210

The introduction is a somehow exhaustive presentation of the general concepts in terms of: (a) the presentation and history of the integrated water resources management, (b) the presentation and history of the management authorities’ approaches to the various sanitation problems faced in the wider Sub-Saharan Africa area, (c) the presentation of the groundwater contamination risk assessment using index-based methods. However, in its present form, there are a series of critical issues to be resolved that in my opinion prevent this paper to be considered for publication as a research article in Water. These issues are highlighted in the remarks listed here below:

Abstract

The abstract does not clearly report the key findings of this study.

"The findings show that landscape pressures have triggered the water and sanitation service regime to embrace alternative approaches to meeting the needs of the vulnerable urban communities living in informal settlements."

This sentence is too vague and the meaning is not clear, please restate.

"The dimension indicators were also deduced from the study findings."

Again this sentence is too vague, please be more rigorous and incisive in the statements.

"This framework can help policy makers to analyze the socio-hydrogeological dynamics and control levers towards managing the growing risk."

Risk of what? please specify.

The introduction section is lacking of a critical review of the state of the art risk assessment method for groundwater contamination in urban areas, the authors cited DRASTIC methods but there are many other approaches like process based models that must be mentioned.

Despite a general formatting issue that limits the text-column width throughout the file, this manuscript is quite extensive as it is 19 pages and 75 references seem quite excessive especially if we think that no hydrogeological data on the informal settlement in Kampala city, named Bwaise, have been provided.

The manuscript’s writing style and content is closer to a technical report than to a research article. The authors are meticulous in listing all available information for interviews, but many if not all aspects about hydrogeological features of the test area are missing (no maps, or tables depicting land use or hydraulic conductivity of the formations, vadose zone thickness, etc…), which makes the manuscript difficult to follow. I could summarize this as follows: first, the information is - in most cases - merely “listed” and not combined, integrated or critically evaluated. This does not help to understand what the authors’contribution is in terms of usefulness of the presentation in the format of a research paper; second, there is too much non-essential information in-text. The connections and different roles/practices of various boards and managing authorities are very hard to be understood when explained in a plain text format. Visual representation can help in doing so in many cases and while figure 3 and 4 attempt to do it, they are too confused with too many loops and labels to be clearly understandable.

The discussion and conclusions sections are very densely written although for authors admission “this study only analyzed only qualitative information on the socio-hydro-geological dynamics influencing sanitation-related groundwater contamination in informal settlements” they does not lead to clear conclusions given the lack of real field hydrogeological data employed. Finally, the real novelty of this paper, namely the inclusion in a DRASTIC approach of the social dimension, has not been proven by observed dataset. Then the statement “These factors were integrated with the intrinsic vulnerability assessment factors (“V”) and specific pollutant character-istics (“P”) to suggest an improved socio-hydrogeological risk assessment framework “V-PLUGINE”.” Cannot be considered reliable, if we consider that the weighing and rating methods are intrinsically affected by Subjectivity in the determination of parameter weighting.