Draining and storing water due to climate change
The Netherlands is designed for the rapid draining of superfluous rainwater. The dryer summers that result from climate change, however, also call for the storage of water. Wageningen researchers collaborate with water managers to discover what steps may be taken to increase water availability for agriculture and nature. For example: deploying deep-rooted crops, soil life or smart dams and drains. Want to know how the Netherlands can make the change?
“Each region has its particular problems, soil and hydrological circumstances, and its unique nature and agriculture. We design tools: different support systems and tools that can be deployed per individual region.”
‘We have known for a while that climate change means our country will be dryer, while at the same time having to deal with flooding through heavy precipitation. But, now that we have seen three consecutive dry years, it is easier to get attention focused on this issue’, says hydrologist-soil expert Mirjam Hack-ten Broeke.
‘The Netherlands is a delta, we have hardly ever faced water shortages. So, everything is designed to drain superfluous rainwater as fast as possible. This will have to change. We will have to work towards retaining water.’ In addition to drainage, which remains necessary due to extreme precipitation in heavy showers and the regular winter-related water surplus.
‘Collaboration is key in making progress’, says Hack-ten Broeke. To determine what steps are needed, various universities and knowledge institutes, as well as water authorities and provinces, join forces. Following this, they search for solutions in collaboration with land-users such as farmers, businesses and nature managers. Together, they investigate how elevated sandy soils may be adjusted to climate change through the collaborative programmes Lumbricus and KLIMAP. Various methods may be deployed, ranging from technical and hydrological measures such as smart dams, to the use of deep-rooted crops and soil life such as earthworms.
The impact of the dry summers is most keenly felt on the elevated sandy soils of Noord-Brabant, Overijssel, Gelderland and Limburg. The sandy soil does not retain water as well as clay soil. Moreover, the elevated sandy soil is entirely dependent on precipitation for its water supply. In other areas in the Netherlands, rivers and the IJsselmeer also add to the water supply.
‘The way rural areas are designed will have to change, and agriculture must follow.’ If you retain more water in the winter, this leads to wet circumstances in the spring. This is something farmers are not accustomed to, as they generally require dryer conditions for ploughing and fertilising. ‘We believe they will eventually benefit from retaining water for the dry summers, but the entire agricultural system will have to adapt to wetter springs. Something easier said than done.’
The researchers, water authorities, governments, agricultural and other businesses collectively consider the transition towards a climate-proof layout. ‘We discuss what the area should look like in the future, and what is needed to reach that goal. These discussions are repeated as new insights arise, and new plans and agreements are reached. This discussion going back and forth between the present and the future is a dynamic process. It is not a roadmap to get from A to B, but rather development paths that support policies as they are developed.’
KLIMAP’s predecessor is the Lumbricus programme, Latin for earthworm. This programme is now drawing to a close but will continue in KLIMAP. Both are multidisciplinary projects that scrutinise soil management, water balance, nature and governance. In addition to soil experts and agriculture experts, governance experts are also involved.
Much has already been learned about the instruments and tools that researchers, water authorities and policy-makers have at their disposal. ‘These have also been improved. For example, in the models that calculate the impact changes in water management or climate have on agricultural yields and nature. Insight into these effects is essential for water management.’
“Participative monitoring” is also part of Lumbricus. This means that the farmers concerned conduct their own measurements of, for example, water levels on their land, and share this information with each other and with the researchers. ‘This fosters an understanding of the issues faced by the water authorities.’
Based on these findings and weather models, farmers can decide how much water to drain or retain, says Hack-ten Broeke. ‘We aim to have farmers operate the smart dams and climate-adaptive drainage or sub-irrigation systems themselves. These new techniques are under development by project partners KWR and en KnowH2O.’
Once new measures are implemented, monitoring how they develop is crucial. ‘Do the measures lead to the desired results and how may a solution in one location be scaled up to span the entire region?’, says Hack-ten Broeke. She stresses that each region faces its own particular problems, soil and hydrological circumstances, and its unique nature and agriculture. ‘In KLIMAP, we design tools: different support systems and tools that can be deployed. But there is never a universally applicable blueprint.’
Subsidence and salination
Even the lower regions in the north and west of our country are increasingly impacted by drought. Thus, researchers and water managers plan to launch a project similar to KLIMAP, focused on the lower-laying areas that face issues such as subsidence and salination in addition to flooding and drought. ‘There too, multiple research institutes and local governments will work towards a future-proof perspective for the short-term and the long-term.’