Climate change increases flooding and drought—researchers are developing solutions for water management

The water cycle refers to how Earth's water resources flow from one place to another, such as from rivers to seas. Occasionally, water stays in various reservoirs, such as glaciers, lakes or as groundwater.

Climate change disturbs this cycle so that the amount of water is not balanced in different parts of the cycle, and water flows either too much or too little. This causes flooding and drought.

Solutions to disturbances in the water cycle are urgently needed, as water is a critical natural resource and the foundation of societies.

"Water is a matter of life and death, because water is needed everywhere. If the water cycle becomes skewed, the effects can be rapid and very dangerous. The ultimate goal of our research is to help understand how to keep the water cycle in balance," says Petteri Alho Professor of Hydrogeography and Remote Sensing at the University of Turku, Finland.

Professor Alho is the Deputy Director of the Digital Waters Flagship (DIWA), which aims to become a top-tier water research cluster and pave the way for the next industrial revolution in the water industry.

At the heart of this revolution are digital twins, virtual representations of physical phenomena that the researchers are developing to model the hydrological processes taking place in river basins and the interaction between water and its environment. Digital twins can be used to test, for example, what kind of flood a two-week heavy rainfall will cause or how the increased water demand of industry will affect the water system.

Digital twins can be used to prepare in advance for various crisis situations or changes. The researchers aim to create a standard for digital twins that can be adjusted to suit different catchment areas. The twins provide very accurate information about water systems for different operators, from farmers to emergency services.

"In the future, we will be able to use digital twins to test and model, for example, drought seasons, heavy rainfall, the need for irrigation in agriculture or groundwater depletion. We are building a comprehensive tool we can use to monitor and anticipate changes and design solutions. Forecasts can predict what happens in an hour or in a hundred years," Alho describes.

Rain gardens can help to retain water

In addition to climate change, the risk of extreme phenomena is increased by people's efforts to accelerate the movement of water, for example, by diverting it away from fields with the help of ditches.

Elina Kasvi, Associate Professor of Geography, leads the contribution of the University of Turku to the RESIST project, which seeks natural ways to retain rainwater where it falls. In nature, various wetlands and the winding banks of rivers slow down water flow. Water retention prevents nutrients from entering water systems, which reduces eutrophication.

In urban areas, water can be retained with the help of rain gardens, which the researchers recommend to private landowners. In a rain garden, a selected part of the garden is allocated to plants that can withstand large amounts of water. Water is directed to the rain garden with the help of gutters.

"Water directed to the rain garden does not burden the stormwater network or flow into other water systems. Anyone can set up a rain garden on the plot of their own house or cottage, for example," Kasvi encourages.

Collaboration needed across borders

The problem with water management is that waterways do not follow land ownership borders. Therefore, decision-making related to water management requires discussion across municipal and state borders.

There have been cases even in Europe where a lot of water has been taken from the upstream of a river and there has not been enough water for the downstream areas. There have not been any major battles for water resources in Finland yet, but the Finnish legislation does not restrict water abstraction from surface water.

To promote discussion and joint decision-making, the researchers have organized workshops for landowners in the same catchment area in Finland, giving landowners the opportunity to talk about the problems they have encountered. The workshops have highlighted the effects of the measures taken on different parts of the area—for example, the straightening of a river bank may have caused drought in certain areas and flooding in others.

The researchers use computational modeling to find out which natural solutions should be implemented in the areas and how climate change will affect the situation.

"It is astounding that the discussions about climate change still use the future tense, even though water flow conditions have already changed significantly. Climate change will increase the number of individual disasters. These include, for example, floods in urban areas, as cities have more and more surfaces that do not allow water to pass through.

"On the other hand, making the effects of climate change visible in our water ecosystem is a long-term process that we cannot yet fully predict," concludes Kasvi.

Provided by University of Turku