When water becomes scarce, its quality often deteriorates

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When water becomes scarce, its quality often deteriorates

Droughts and heat waves cause great economic damage. To reduce water scarcity, hydrologist Michelle van Vliet advocates a better understanding of the interaction between water quality and water use.

Water scarcity is more than just a physical lack of water. Growing water scarcity has three causes: decreasing water availability, increasing water use and deteriorating water quality, making it unsuitable for certain uses or functions. Droughts and heat waves are particularly critical because they have an amplifying effect on all three of these causes.

Each of these three components alone contributes to water scarcity, but they also do so together by interacting with each other. For example, reduced water availability during a drought increases water scarcity directly, but also indirectly because less water is available to dilute potential pollutants, which in turn leads to a deterioration in water quality. For example, we see an increase in salinity during a drought, resulting in a reduction in the use of irrigation water.

In an earlier study , in collaboration with an international team of researchers and published last September in Nature Reviews Earth & Environment, I pointed out that droughts and heat waves negatively impact water quality in more than two-thirds of all case studies analyzed worldwide. Droughts and heat waves also increase water use by various sectors, such as for domestic use and irrigation, leading directly to increased water scarcity, but this also affects water quality indirectly. Understanding the interaction between water availability, water use and water quality is therefore essential for finding sustainable water management solutions.

Salt in river water

All sectors, including irrigation, domestic use and even energy and industry, depend on clean water. Paradoxically, however, they simultaneously lead to water pollution. For example, increased salinity negatively affects irrigation for agricultural activities, but large-scale irrigation also contributes to increasing the salinity of rivers worldwide in the first place.

Sectors depend on good quality water but they pollute water during use. For example, high concentrations of drugs, pathogens, and other contaminants limit household (drinking) water use, but households also happen to be the main source of drug and pathogen contaminants in water.

Therefore, to cope with these problems, we should pay more attention to the interaction between the three components of water availability, water use by various sectors, and water quality. Only then can we make better estimates of water scarcity, especially under extreme weather conditions. The good news is that with the increasing availability of data, computing power, and better capabilities to intelligently process this data, technical development is also possible to map said interactions.

Water storage

But, finding appropriate solutions for sustainable water management requires more than just a better understanding of the causes for water scarcity. We must also learn to think in scenarios for water management. Furthermore, this involves not only traditional approaches to counteracting water scarcity (for example, increasing water availability by storing more water) or reducing sectoral water use, but also improving water quality (such as reducing pollutant loads and expanding treatment and reuse of treated wastewater).

Climate change is one of the greatest challenges facing humanity in the 21st century. One of the main consequences of global warming is an increase in the intensity and frequency of extreme weather events such as heat waves, droughts and heavy rainfall. The increase in these events threatens water safety and security in many regions around the world, including the Netherlands, and presents difficult challenges. This requires a new way of thinking about water management, driven by improvements in both water quantity and water quality. Only in this way can we improve water security in a world where extreme weather events are becoming more intense and frequent. The challenge for the new Dutch government, of whatever composition, is to ensure that the country does not run out of clean water in the future.

This opinion piece was published online December 22, 2023, as a climate blog of NRC. Michelle van Vliet is associate professor in the Department of Physical Geography at Utrecht University. She was recently invited by the journal Nature Water to present a future vision on water scarcity and sustainable water management.

Scientists from Utrecht University regularly write about their research in the NRC’s climate blog. They work together in the strategic theme Pathways to Sustainability.