Although access to clean water has been recognised as a human right since July 2010, its practical implementation is lagging a long way behind: nearly a billion people worldwide still have no access to clean drinking water. The global population, which currently stands at 7.2 billion, is expected to rise to 9 billion by 2050. This will result in a growing need for water, food and energy, particularly in developing and newly industrialised countries. In many regions, demand will reach the limits of the resources available. Furthermore, climate scenarios assume that global temperatures will rise by between two and six degrees Celsius by 2100, which will exacerbate existing water problems and create new ones.
The effects – which will depend on a location’s initial circumstances and its climate, geography and politics – will be very different in each case. Although it might seem that we have an abundance of water (it covers more than 70 percent of the Earth’s surface), only a very small proportion of that (around 0.3 percent) can be taken directly from lakes, rivers and groundwater to be used as drinking water. Water is also not distributed evenly around the world and is used in varying amounts (as drinking water, in industry, for energy generation, for growing crops) in different regions and seasons. What is more, water is often harnessed for especially water-intensive applications in places where it is already very scarce.
Europe will not escape the effects of climate change. In some parts of the Mediterranean that are already very dry, precipitation is expected to decrease by 20 to 40 percent by 2070. Elsewhere, extreme precipitation will make floods significantly worse and considerably more common. Water and wastewater technologies need to be adapted so that they can cope with these changing conditions. The main scientific challenge lies in developing complex yet reliable observational and forecasting systems that work at the drainage basin scale and can reach up to 100 years into the future.
In arid and semi-arid regions of Asia, Africa and Latin America, we are mainly dealing with a quantitative water problem that is being exacerbated by an ongoing decline in water quality. The challenges here are to use water more efficiently (particularly in agriculture), to develop innovative technologies for conserving or reusing water, to produce accurate water balances, and to ensure sustainable water management.
Then there is the ongoing need to find ways of accessing new water resources. We will also have to start shifting water-intensive activities to areas that have a lot of water – at the moment, arid countries often export water-intensive agricultural products at the expense of their already scarce water supplies.
Water management: Think globally, act locally
If we are to overcome the challenge of meeting future water demand, we must develop and implement integrated approaches to using and managing water resources in a sustainable way. The approaches will have to be adapted to take account of variations in resources across regions, different levels of use, and anticipated changes in supply and demand. In this sense, the well-known principle that tells us to think globally, act locally has a very specific meaning. To ensure the long-term security of our water supply, we must use water in a way that balances with the amount available, the quality, and the ecological roles that the surface water and groundwater play.
However, water resources in themselves are not the only thing that we humans need. The natural functions of aquatic systems are also essential to us. Bodies of water perform crucial ecological services by providing food, drinking water and energy, transport and assimilative capacities, aesthetic and cultural value, and many more things besides. No other system or technology can replace these functions.
This means a modern and sustainable water resources management system cannot be developed in isolation and must take account of more than just the water sector. The key lies in adaptation strategies, flexible infrastructures and a significant increase in efficiency across all types of water use.
This question was answered by Prof. Dietrich Borchardt, speaker for Sustainable Water Resources Management and head of the Aquatic Ecosystems Analysis Department at the Helmholtz Centre for Environmental Research (UFZ).