In one of his projects, Roland Barthel (second from right) looked into the state of water resources on the two Koster Islands in northern Bohuslän. Because of the large proportion of summer residents on the two islands, the water supply varies a great deal between the summer and winter months.

Expensive drops for a more secure future

Ninety-seven per cent of the world’s usable fresh water is stored as groundwater. Despite this, we know very little about groundwater and how, for example, it is being affected by climate change. Hydrologist Roland Barthel wants to change this.

Because of the dry weather pattern in the summer of 2016, southeastern Sweden was affected by water shortages. The situation was worst on Öland, but Gotland and the eastern coast of Götaland also experienced major problems from lack of access to water.

‘In Sweden there should be no water shortages’, Roland Barthel says. ‘We have many large lakes, particularly Vänern and Vättern, so there is more than enough for everyone to get water. Our problem is the distribution of the water. In a sparsely populated country with great distances, we need to have long water pipes, and we haven’t built up a good system for that.’

Groundwater levels in large reservoirs, June 2016. Red color indicates levels far below normal.

When water shortages arise in a region, they are mainly due to two aspects. There’s the natural aspect, whether there is more or less water in the groundwater reservoir, and the technical aspect. If there is a good and well-developed water supply system that can handle water shortages over a certain period of time, no problems arise. It can be a matter of desalination of seawater, for example. Öland lacked this type of system.

Professor Barthel is a hydrologist and has conducted groundwater research for more than 20 years. Groundwater systems are complex. The water can be anywhere from a few centimetres to 100 metres below the surface of the ground, and a variety of factors influence what the level in an area is. If it rains a lot and intensely, a greater proportion of the water will run off from the surface of the land and less will penetrate into the groundwater, but if it rains less intensely, more water sinks into the ground. If an area gets a lot of rain in the winter and spring instead of in summer, more water goes down into the groundwater because less water evaporates.

‘There are no two places on Earth where groundwater behaves exactly the same’, says Roland. ‘But the time series we have over how groundwater has behaved are short, often no more than 50 years old, and there is very little understanding of how groundwater systems actually respond to climate change. This makes the model results that exist very uncertain.’

Roland has recently launched a three-year research project in which he and his colleagues will study measurement data from groundwater systems. The goal is to find correlations between groundwater resources and climate changes to see how future climate changes may affect groundwater systems in Sweden. Because relatively little measurement data has been collected in Sweden, the data to be used for method development comes from measurements made in Bavaria and Baden-Württemberg in southern Germany. Eleven million people live there in an area somewhat larger than the regions of Västra Götaland and Halland. As a result, a well-developed water distribution system has been built to convey water from Germany’s largest lake, Lake Constance, and other sources. The effort to supply the population with water has also led authorities to conduct measurements of groundwater there to a much greater extent than Sweden.

The measurements in Germany come from an area with large differences in climate, geology and topography, which encompasses virtually all the conditions that also exist in Sweden. The question that Roland wants answered is: when can you foresee that an approaching water shortage? He shows a series of images of measurements of groundwater supplies during 30 years at various locations in southern Germany. Some curves slope slowly downward, while the others vacillate strongly between high and low values in a short time. By studying how the climate correlated with the measurements, researchers can see how it has affected the groundwater systems on that particular site and in that sort of environment.

‘When we see what it looked like in the past, we can predict what the future will look like’, says Roland. ‘The goal is to create a tool kit that we can use in Sweden to investigate how groundwater will react to changes in different places – in urban environments, in the countryside or along the coast. In the past I’ve used large, complex models that require a great deal of data and time, but they did not provide reliable results.’

The climate models that have been created in Sweden indicate that the climate will become warmer and drier in southeastern Sweden and wetter in western Sweden. Generally, there will be more rain in the six cooler months of the year. ‘If this will lead to more or less groundwater in a region is very difficult to determine because of the numerous and complicated processes going on that have an impact. On one hand, higher temperatures lead to more evaporation and less snow, but on the other hand they also lead to longer growing seasons.’

In addition to the natural and the technical aspects, there is a third aspect that can affect if and when a water shortage occurs. Roland refers to this as a social aspect: what we perceive as water scarcity? As an example, he cites a person staying in a summer cottage who is accustomed to being able to shower only a few times a week at the most.

‘In that case, greater scarcity is required for the person to perceive it as a water shortage. On the other hand, if you are accustomed to having water as soon as you turn on the faucet, maybe you have a different view of having a water shortage.’

In addition, it’s relatively common to have a private well in Sweden. Close to 1.2 million Swedes get their water from private wells annually, and that figure rises by one million during the summer when many live in their summer cottages.

‘There is a psychological factor at work here. Many people want to have their own well with their own water – even if the water tastes bad’, Roland says with smile.

Although the summer of 2016 demonstrated that water shortages can occur in Sweden, Roland doesn’t think that Sweden will experience this as a big problem in the future. The solutions available today are sufficient to solve the problems that may arise.

‘But worldwide, there are many regions that have very big problems with their water supply, and in those regions there are not always technical possibilities and financial resources available to eliminate the problem. At the global level, water scarcity is one of the most serious dangers of our time.’