Tierras y Aguas

Water for environment: Incorporating environmental flows into water stress indicator 6.4.2

The Agenda 2030 for Sustainable Development is an ambitious plan of action for “people, planet and prosperity”, and so is the dedicated goal on water and sanitation (SDG 6), which plays a key role in realizing the Agenda. To ensure appropriate monitoring and reporting of results at global level, UN Member States have developed a set of global indicators through the Inter-agency and Expert Group on SDG Indicators (IAEG-SDGs).

For each global indicator, the IAEG-SDGs has appointed a custodian agency responsible for compiling and verifying country data with the purpose of global reporting. In this context, FAO is the custodian agency for the indicator 6.4.2 on the level of water stress, which is calculated as the ratio between (a) the amount of total freshwater resources withdrawn and (b) the total renewable freshwater resources after detracting the amount of water needed to support existing or desired environmental services also indicated as environmental flow requirements (EFR).

Following an initial expert meeting held at FAO in Rome in April 2018, guidelines for a minimum standard method for global reporting on environmental flows (EF) were published in 2019. Their main purpose was to assist countries in the process of producing data and information, as part of the required global reporting on Water Stress Indicator 6.4.2 established for SDG 6 Target 6.4. Presently, this is the only indicator across the SDGs that explicitly considers the vital role of environmental water in ensuring sustainable water use. Indicator 6.4.2 and supporting guidance, thus provide a significant opportunity to underscore how environmental flows underpin SDG 6 and many other SDGs, including those focused on food security and the conservation and wise use of freshwater and estuarine ecosystems. 

The 2019 FAO guidelines outline the minimum standard method based on the Global Environmental Flows Information System (GEFIS) currently being used to generate the EF data for the global SDG 6.4.2 report on national water stress. Countries that have more comprehensive and accurate data on environmental flows are encouraged to make use of their own national and subnational data to (i) validate the FAO global dataset calculated using the minimum standard method, and (ii) add additional information to their Voluntary National Reviews on the SDGs.

In this framework a second expert workshop on “Incorporating environmental flows into water stress indicator 6.4.2” was held online from 20 to 22 October 2020. More than 60 experts from 23 countries participated, including members of government institutions, academia and UN agencies. Two aspects of EFR assessment were discussed: 

  • The role of groundwater within EF assessment.
  • The concept of the Environmental Management Classes (EMC) as a tool for assessing and allocating water resources.

These two topics enter directly in the computation of indicator 6.4.2, both in the assessment of available freshwater resources and of freshwater withdrawal. They are also relevant to other SDG6 indicators, such as 6.5.2 on transboundary waters and 6.6.1 on water bodies.

The discussion highlighted the relevance of the matter to implement an integrated water resources management process. The debate focused on the importance of a better understanding of the relations between surface water and groundwater, with a special consideration for the difference between shallow and deep groundwater. 

About the existing EFR tools available for global assessments, it was concluded that they need to be improved due to their insufficient performance in the drier areas and to the lack of scope for improving the system using country-based data. The latter issue was particularly felt by participants from governmental institutions, who also highlighted the need for specific training and capacity development opportunities.

At the end of the three-day webinar, participants decided to identify a way forward aimed at continuing the technical debate as well as at initiating a policy support activity involving all interested stakeholders. 

Watch the video interview of world recognized experts on various technical, scientific and policy-related aspects of the assessment of environmental flows, recorded for the Second expert workshop on environmental flows.

Download the publication "Incorporating environmental flows into “water stress” indicator 6.4.2 - Guidelines for a minimum standard method for global reporting".


The project “Integrated Monitoring Initiative for SDG 6 - IMI-SDG6" is carried out by FAO, along with other UN agencies coordinated by UN-Water. The main objective of the project at this stage is to support countries to increase their technical and institutional capacity for the monitoring and reporting of the indicators related to Goal 6 targets "Ensure availability and sustainable management of water and sanitation for all".

The Land and Water Division of FAO  is leading the work related to target 6.4: "By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce the number of people suffering from water scarcity." Data collection and management are made through the AQUASTAT database.