Impacts of Global Water Quality on Water Scarcity and Potential Solutions

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Episode recorded June 30, 2023
Episode released on October 19, 2023

Michelle van Vliet is a Professor in the Dept. of Physical Geography at Utrecht University. Her research focusses on global change impacts and adaptation in relation to water resources availability and water quality for sectoral water uses (irrigation, domestic, energy) and ecosystems.

Highlights  |  Transcript

1. The Netherlands and neighboring countries are facing challenges with meeting EU Water Framework Directives, particularly with respect to nitrogen targets and the current 2027 target. In 2021, the Government announced major transitions for nature restoration to reduce nitrogen below the threshold. Farmers were dissatisfied, blocking highways etc.  Excess nitrogen is attributed to high population density (18 million over 42,000 km²), intensive agriculture, industries. shallow groundwater, and humid climate. 
2. EU Water Framework Directive (passed in 2000): need to achieve good quality status by 2027 for nutrients and other contaminants (metals, microplastics, PFAS, and pharmaceuticals). Water quality issues exacerbated by droughts with less dilution of contaminants. Improvements were recorded with half of the waters in the Netherlands meeting the water quality standards, but less than one percent of the Dutch surface waters complied with the standards for good ecological status according to the Water Framework Directive. The low score is mainly due to poor biological quality as well as to excessive concentrations of substances including nutrients, heavy metals and other persistent pollutants.
3. Approaches to assessing global water quality used by van Vliet’s research group include:
4. process based modeling (DynQual, water temperature [T], Total Dissolved Solids (TDS) Biological Oxygen Demand [BOD], and Fecal Coliform [FC.]
5. Machine learning approach developed by World Bank based on Random Forest and considering temperature, Dissolved Oxygen (DO), electrical conductivity (EC), pH for acidification, nitrate-nitrite (NO₂NO₃), and total phosphorus concentrations (total P). 
6. Global pollution can be characterized by: 
   1. pollutants of poverty resulting from poor sanitation and litter (organic pollution, pathogens, and fecal coliform)
   2. Pollutants of prosperity resulting from more intense economic activity (NOxN, pesticides, plastics, and pharmaceuticals)
7. Examples of hotspots depend on contaminants: 
   1. salinity, organic pollution, and fecal coliform in India and E China primarily
   2. nutrients in W Europe and parts of US attributed to agricultural loading 
   3. Africa will become a major hotspot because of projected population growth, limited wastewater treatment, and climate change (increased droughts restricting dilution)
8. Global trends in water quality (1990 – 2010)
   1. Water quality deterioration: 30% of land surface, particularly global South, Africa
   2. Water quality improvement: 20% of land surface
9. Population impacted by water scarcity globally increased from 30% to 40% by including water quality issues (e.g., T impacts on power plants, salinity on irrigation etc.). Largest impacts in water scarcity hotspots. Here sector water withdrawals contribute to water scarcity directly, but also sectoral return flows deteriorate water quality downstream, hampering other uses, particularly in regions with limited wastewater treatment. 
10. Climate change may result in reductions of power generation for thermoelectric power plants globally by 60% because of temperature constraints. Adaptation strategies include conversion from once-through cooling to cooling towers or dry cooling, fuel switches, and efficiency improvements. 
11. Droughts in Europe over the last two decades resulted in large reductions in nuclear power generation because of water scarcity and temperature constraints. 
12. Global wastewater production: 360 km³/yr (municipal and industrial sources)
    1.  48% released to environment untreated (173 km³/yr, highest in Latin America and S Asia); 
    2. 63% collected, 
    3. ~40% intentionally reused (40 km³/yr; e.g. Kuwait, Qatar) (Jones et al., 2021). 
13. Global water quality simulations with the DynQual model show that the Sustainable Development Goal SDG 6.3 target of halving the proportion of untreated wastewater globally by 2030 is in most regions insufficient to meet water quality targets. 
14. Desalination of seawater and inland water resources is also considered a new source of water to alleviate water scarcity: 16,000 desalination plants; 35 km³/yr desalination; 52 km³/yr of concentrate (Jones et al., 2019).
15. Michelle is hopeful about future but indicates that urgent actions are needed in terms of improving water quality. Water quality matters in studying the whole nexus of water, food, energy, and ecosystems. This is important within the context of climate change and increasing hydroclimatic extremes (such as droughts, heatwaves, floods). We need to better understand the drivers of these issues also to come up with an adequate set of solutions.