Opinion | When water becomes scarce, its quality often deteriorates

Water scarcity is more than just a physical lack of water. The growing water scarcity has three causes: decreasing water availability, increasing water use and deterioration of water quality, making it unsuitable for certain applications or functions. Droughts and heat waves are particularly critical because they compound all three of these causes.

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

In a previous studyin collaboration with an international team of researchers and published last September in Nature Reviews Earth & Environment, I already pointed out that drought and heat waves have a negative impact on water quality in more than two-thirds of all case studies analyzed worldwide. Drought and heat waves also increase water use by various sectors, such as domestic use and irrigation, which directly leads to increased water scarcity, but also indirectly affects water quality. Understanding the interaction between water availability, water use and water quality is therefore essential for finding sustainable solutions for water management.

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 impacts irrigation for agricultural activities, but large-scale irrigation also primarily contributes to increasing the salinity of rivers worldwide.

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

In order to tackle these problems, we should therefore pay more attention to the interaction between the three components of water availability, water use by the 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 the increasing availability of data, computer computing power and better options for processing this data intelligently also make technical development possible to map these interactions.

Water storage

But finding suitable solutions for sustainable water management requires more than just a better understanding of the causes of water scarcity. We also have to learn to think in water management scenarios. In addition, this not only concerns traditional approaches to combat water scarcity (for example increasing water availability by storing more water) or reducing sectoral water use, but also improving water quality (such as reducing the burden on pollutants and the expansion of 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 us with 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, whatever its composition, is to ensure that the country does not run out of clean water in the future.

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