Villholth, K., Klingbeil, R., Ruz Vargas, C., et al., 2020. Assessing Groundwater Quality: A Global Perspective. Importance, methods and potential data sources. Presentation at the SADC 3rd Groundwater Conference, 24-26 Nov 2020.

2. Karen G. Villholth, Principal Researcher (IWMI),
Ralf Klingbeil, Senior Expert Groundwater (BGR),
Claudia Ruz Vargas, Researcher (IGRAC)
Assessing Groundwater Quality:
A Global Perspective
Importance, methods and potential data sources
submitted as part of WWQA contribution to UNEA 5, 2021-22

3. With thanks for the contributions from the
“Friends of Groundwater”
Dr. Caroline Delaire (Aquaya)
Dr. Chloé Poulin (Aquaya)
Dr. Dan Lapworth (BGS/IAH)
Dr. Pauline Smedley (BGS/IAH)
Dr. Ralf Klingbeil (BGR)
Dr. Frank Wagner (BGR)
Dr. Joel Podgorski (Eawag)
Prof. Dr. António Chambel (IAH)
Ms. Jane Dottridge (IAH)
Prof. Dr. David (Dave) Kreamer (IAH)
Prof. Bruce Misstear (IAH/TCD)
Dr. Neno Kukuric (IGRAC)
Ms. Claudia Ruz Vargas (IGRAC)
Dr. Karen G. Villholth (IWMI)
Dr. Niels Hartog (KWR)
Prof. Dr. Craig Simmons (NCGRT / Flinders)
Dr. Martin Andersen (NCGRT / UNSW)
Dr. rer. nat. Hans Duerr (RUB)
Prof. Dr. Tobias Licha (RUB)
Prof. Dr. Junguo Liu (SUSTech)
Ms. Lucy Lytton (WB)
Mr. Dylan Blake (Umvoto)
Dr. Kornelius Riemann (Umvoto)
Dr. Alice Aureli (UNESCO IHP)
Ms. Luciana Scrinzi (UNESCO IHP)
Dr. Manzoor Qadir (UNU-INWEH)
Dr. Issoufou Ouedraogo (UFDG)
Prof. Dr. James (Jim) Jawitz (UFL)
Prof. Dr. Seifu Kebede Gurmessa (UKZN)
Prof. Dr. Tom Boving (URI)

4. “Friends of Groundwater” in the World Water Quality Alliance

5. World Water Quality Assessment &
World Water Quality Alliance
United Nations Environment Assembly (UNEA) Resolution 3/10
“Addressing Water Pollution to Protect and Restore Water-related
Ecosystems” (2017, UNEP/EA.3/Res.10):
“16. Requests the Executive Director of the United Nations
Environment Programme, within available resources: (…)
(e) To cooperate with other relevant organizations, including
through UN-Water, to develop a world water quality assessment
for consideration by the Environment Assembly at its fifth session;”
• Geneva, CH, 2018: 1st global meeting
• Ispra, I, 2019: 2nd global meeting
• Alliance: Gobal multi-stakeholder network of approx. 100
institutions
• Aim: Develop a World Water Quality Assessment (WWQA)
• 3 African use cases, c. 10 work streams, governance (SAC, TAC)
• “Friends of Groundwater” (FoG): c. 30 members from 20
organizations, groundwater quality related aspects of WWQA

6. Threats to groundwater quality
Groundwater is facing many threats from the effects of agricultural intensification, urbanisation,
population growth and climate change:
• Groundwater salinization from irrigated agriculture, over-pumping drawing in old saline water, and
sea water intrusion into coastal aquifers
• Nitrate pollution
• Microbial contaminants
• Groundwater contamination from industry and urbanisation
• Emerging contaminants associated with industrial activities, urbanisation and agriculture

7. Contaminants can occur naturally in groundwater
Several naturally-occurring (geogenic) contaminants can lead to serious
health problems if present at high concentrations in groundwater supplies.
Notable examples: arsenic, fluoride and radionuclides (U, Ra, Rn)
Probability of naturally
occurring arsenic in
groundwater exceeding
the WHO guideline of
10 µg/L (Podgorski & Berg,
2020) at the global scale.

8. Challenges for a global groundwater
quality assessment
• Methodological
• What are priority parameters?
• Upscaling local studies to regional assessments
• The 3rd (3-D flow) and 4th (time) dimensions
• Poor sampling or analysis procedures;
poor monitoring well construction
3-D nature of
groundwater flow
and contaminant
migration:
pathways present
in poorly
productive
aquifers (left) and
productive
aquifers (right)
(Archbold et al.,
2016).
Seasonal variations in
groundwater chemistry,
Bergen region, Norway
(Data from Geological
Survey of Norway,
reproduced in
Misstear et al., 2017)
Long-term effect:
modelled global
increase in nitrate
stored in
unsaturated zone,
potential impact
on groundwater
quality for decades
(Ascott et al., 2017)

9. Global sources of data and information:
Global Assessments & Overviews (e.g. IGRAC, BGS)
Global studies using modelling (e.g. EAWAG GAP)
UN GEMStat (GEMS/Water Programme)
Current world-wide assessments:
Country data: SDG 6.3.2 ambient water quality
World Water Quality Assessment (UN Environment)
Regional and country–wide data sources
Challenges and opportunities for a global groundwater
quality assessment & groundwater quality management
Data and information challenges:
• Mandate and use of national data sources
• Opportunities to use Citizen Science
• Earth Observations
Groundwater Protection Zones around a production
borehole (Rajkumar & Xu, 2011)

10. • Groundwater quality will remain a key focus area in Africa, as:
 70% of the African population are reliant directly on GW for their basic water needs
 GW is increasingly being developed for multiple purposes, including urban supply
and economic sectors (agriculture/food processing, etc.), requiring adequate water
quality
 Groundwater monitoring, assessment and management remains an area of
relatively low technical and human capactiy
• Established partnerships with SADC, AMCOW, ANBO, etc. will be strengthened through
focal and strategic initiaitves related to water quality
• SADC-GMI and APAGroP (AMCOW Pan-African Groundwater Program) will be natural hosts
for groundwaater programs going forward
• AMCOW is Member of the Strategic Advisory Committee of the UNEP World Water Quality
Alliance
• AMCOW is presently engaged in SDG monitoring with strong opportunities to expand role
in GWQ monitoring
• SADC is increasingly working on GWQ issues and can support on regional monitoring
aspects
• Other regional and river basin organizations will be critical to engage going forward
Opportunities for regional and continental integration

11. Examples of relevant initiatives in the SADC region
• GW use case in Cape Town
• SADC GW Map and Atlas
• SADC GW drought risk maaping
• GW – sanitation link, e.g.:
 New initiatives on Managed Aquifer Recharge using wastewater (e.g.
RSA)
• New inititives on GW remediation
• Salinity issues:
 Coastal salinity intrusion
 Salinity increases in water supply from deeper aguifers/aquifer sections
• Point of use water treatment

12. Fluoride problem areas
Salinity problem areas
Nitrate problem areas
Villholth et al., 2011

13. Key messages 1 of 2
1. Increased attention to (ground)water quality is of utmost importance for
the achievement of the SDGs.
2. A dedicated global groundwater quality assessment is necessary and
timely.
3. There is a large variability of anthropogenic and natural chemical and
microbiological contaminants that are found in groundwater across the
globe. Their large range of characteristics requires expert knowledge.
4. Groundwater systems are heterogeneous, three-dimensional water
reservoirs. Groundwater contaminant distributions are therefore particularly
challenging to map.
5. Information and data on groundwater quality are very variable across the
globe, with often less information available in countries of the Global South.
For a comparable global assessment, substantial efforts are needed.

14. Key messages 1 of 2
6. Groundwater quality needs to be understood at various scales depending
on the issues, in relation to different end uses e.g. drinking water,
ecosystems, food production, energy production and others.
7. Groundwater monitoring programmes need to be targeted and designed
according to the purpose of the monitoring.
8. Important new advances are becoming more common, e.g. earth
observations and GIS, citizen science, machine learning, and numerical
modelling of contaminant fate and transport, complementing traditional
methods.
9. Most monitoring programmes for groundwater quality are based on
national level legislation and regulations, where these exist, but special
attention is required in the case of transboundary aquifers.
10. Local-to-global partnerships and investments in research, capacity
development and evidence-based policymaking are required to advance
management of groundwater quality sustainably.

15. A way forward
• Global GWQ Assessment Portal
• Global GWQ Assessment Network - building on GEMS/Water and SDG target 6.3.2
• GWQ Monitoring Programmes at national level, inc. institutions, purpose, parameters,
methodology, availability and accessibility
• WWDR 2022 “Groundwater: Making the Invisible Visible”
• Other activities related to groundwater quality for
WWD 2022.
• Assistance to national GW assessment programmes,
capacity development, advocacy at various levels
• Upscaling and regionalisation - main FoG research
activity: regional/global modelling (e.g. machine
learning), “use cases”, remote sensing,
Citizen Science, etc.

16. Suggested citation:
Friends of Groundwater, 2020. Assessing Groundwater Quality: A Global Perspective. Friends of Groundwater for
the groundwater work stream of the World Water Quality Alliance (WWQA). Contribution to UNEP documents on
the World Water Quality Assessment (WWQA) submitted to the fifth session of the UN Environment Assembly,
UNEA 5, 22 -26 February 2021.
Assessing Groundwater Quality:
A Global Perspective
Importance, methods and potential data sources