This paper describes a method to disaggregate the indicator 6.4.2 (level of water stress) by major river basin. The analysis was performed using the GlobWat soil water balance model and global geospatial data consistent with national statistics published in AQUASTAT, the FAO’s global information system on water and agriculture. When a river basin spans across more than one country, the water stress calculated by country can be very different from that calculated by river basin since the counting of the renewable freshwater resources from one country to another is highly dependent on the official agreement and treaties that regulate the flow of those resources between countries. This problem is hydrologically solved once the accounting of the water resources is done on the major river basin as a whole. The disaggregation by river basin allows the identification of hotspots where actions should be prioritized and reveals that the area affected by a high or critical water stress spans across all continents with the exception of Oceania. It offers also the possibility of an analysis of freshwater withdrawals by sector, which may become crucial for the definition of water management policies in the context of the economic development of a country.
All changes are highlighted in red in the attached revised pdf
Grammar and spelling has been revised throughout the paper.
Replies to Mr. Kuriqi
A list of acronyms has been added
The introduction has been revised and the aim and novelty of the work has been made more explicit
We checked and found that all variables are described and explained in the text
The chapter on limitations has been expanded. However, divergent views on the criteria of the indicator have been addressed in the work, especially in the section on water consumption, which has been strengthened by adding text and by moving one map from the appendix to the main body (figure 9). Moreover, we could only find a very limited number of relevant publications, all quoted in the paper.
Replies to Mr. Mbatha
This is indeed a technical paper, addressed to technical and scientific specialists in relevant institutions worldwide. Less technical works are published by the custodian agencies of the SDG indicators
The indicator is part of the set of global indicators selected by the United Nations to monitor the progress in the implementation of the Agenda 2030. As such, each country is committed to monitor it. It is not the intended purpose of this paper to analyse and discuss the actual monitoring of the indicator by countries.
The aim of the paper is to describe the method used to spatialize and disaggregate the indicator and its variables at basin level. An analysis of the social and environmental impact of a high level of water stress is beyond the scope of this article.
The issue of improving data collection has been addressed by adding two paragraphs in the limitations section and stressing the point within the results section near Eq.5
The indicator is meant to be used for monitoring SDG 6.4 at global level, through its assessment at country level. The disaggregation method described in the paper aims indeed at providing a tool for better addressing regional and sub-regional assessments.
The paper is aimed at a technical audience. However, we consider that all formulas are adequately explained in that context
We have revised the result section and eliminated the suggestions towards the linkages with population density, as we considered that it was beyond the scope of the paper, and would have needed a much more thorough discussion.