Water - for recovery of the climate - A knowledge exchange between Limburg, Slovakia and Norway

Submitted by Ase Johannessen | published 23rd Dec 2021 | last updated 11th Jan 2022
South Limburg urban landscape

Background

The Water Authority in South Limburg in the Netherlands contacted the Global Center on Adaptation in May 2021 to learn about international examples of flood management in rural and urban areas. This was part of the innovation work, led by Innovation manager Anne Buit, to explore lessons learnt from other countries. Other countries experiences were interesting because South Limburg is relatively hilly compared to the rest of the Netherlands, and good experiences might be found abroad to learn from. After some searching, Norwegian and Slovak experts were contacted to provide relevant knowledge. The Silly soils of Slovakia, and its hilly topography creates certain similar conditions with the Netherlands, and both countries have experimented with flood risk measures for many decades, and much more.  

Contents

  • Rationale for the exchange
  • Water in Balance program in South Limburg (see attached PPT)
  • Discussion and input by Slovak and Norwegian experts
  • Presentation from Slovakia (see attached PPT)
  • Discussion including solutions from Norway

Rationale for the exchange

In July 2021 Western Europe was taken by surprise by an extreme rainfall event in the summer. Such volumes broke historical records. Rainfall events of such magnitudes are more usual in the winter. The cause of the massive flooding was due to a number of reasons. In July 2021 there was a so called “cold pit” or a low-pressure over a small area in Belgium and Germany, which meant that the weather system stayed in the same place for a longer time. There were also warm days so that the air could contain a lot more water. The rain thus became local and heavy. The soil was also saturated from the previous period of rain, preventing infiltration. The damage was also caused by rapid runoff from hilly areas, which could not retain the rain. The South of the Netherlands, which lay downstream from the main affected areas, had thankfully no human casualties, but the flood was highly costly to society, incurring more impact than the floods in 1993 and 1995.

The Limburg Water Authority, in the South of the Netherlands, are expecting more extreme events to become more frequent especially during the summer. Due to climate change, the Water Authority does not expect history to help in predicting future events, making future predictions uncertain.

The Limburg Water Authority has a successful program to manage water in a changing climate - addressing too much and too little water (floods and droughts). However, the Authority perceived that more could be done, and in the spirit of innovation, they were seeking input on how to improve practices, especially relevant for rural hilly environments, with silty soils. Especially they perceived that more could be done in terms of nature-based solutions to retain water in the landscape. In recent floods they had for example observed that flood waters from farmlands were full of sediments, which is a sign that the retention measures can be improved. A program for an exchange was hence developed including the presentation of the existing water management measures in Limburg, as well as including lessons learnt from Slovakia and Norway with discussion between the involved experts. 

"Water in Balance" in South Limburg (available as PPT)

The Limburg Water Authority work in the program “Water in balance” – where they try to find the balance: Not too much or too little water. This video summarizes the program.

In the Water in Balance program they are working on four "buttons" to find solutions:

  • Rural environment – involving farmers and nature organisations
  • Urban environment – involving municipalities, and their inhabitants
  • (Regional) water systems – which is the responsibility of the Water Authority
  • Houses / property - when the Water Authority cannot find solutions in the water systems it needs to give ideas to inhabitants to protect the houses and reduce the damage

The rural environment

The discussion focused on the rural environment. (Another exchange will be organised to address the urban environment). To store flood waters, there are many infiltration projects and broadening of brooks in Limburg. They are also digging water retention basins, along the water courses with about 500 basins in the south of Limburg. However, it creates a perforated landscape, which is not always accepted by citizens.

Anne showed how they have measured runoff from cornfields, and which showed that good quality soil and plants can reduce it. In these trials with farmers, they collaborate with the University of Wageningen.

See the attached PDF for more details on the presentation. 

Discussion and input by Slovak and Norwegian experts

Linking land use to extreme precipitation events

The Slovak experts suggested that the regional land use in west Europe - with large urban zones in Germany, including the Ruhr area, that form a "desert" in terms of water vapor flows, contributed to creating the situation with heavy rainfall in July. With climate change and higher temperatures, evaporation from the ocean will be higher and water vapor transport occurring inland by air and further from the seashore. With the Dutch positioned less than 200 km from the ocean, a good prediction is that they will be hit more frequently by these extremes in the future. More background on how water vapor flows can be affected by land use can be found here in a video produced by the Slovak experts. 

Suggestions for further improvement of the Limburg approach

Peter Gabris from Slovakia applauded the Limburg Water Authority saying that all low hanging fruit is already taken. He noted that most storage basins in Limburg are located in relation to the rivers, (which is to be expected). He suggested to consider to further improve the areas upstream of the retention areas on soft grounds, to try to slow down surface runoff, during extreme precipitation.  Those measures might be cheaper, simply to avoid getting the water to the regular surface waters.

Peter also suggested to use the storage basins for multiple purposes, for recreation or planting something, and not only for the 2-3 times per year when they are needed. This builds acceptance of society for these basins.

Furthermore, Peter noticed mud flows in the photos of the July flood. He said: “This is almost always a signal that there is an opportunity to do something. For example, if agricultural practices are not taking the risk into account or if the region is not arranged in the right way.” [Limburg agreed].

What was the best way for Slovakia to convince farmers? In Slovakia it is much easier to get younger and farmers owning smaller plots of land, to consider changes to practices. Michal Kravčík has done a lot to educate government –now they [the government] just need to act further on this knowledge.

Bent Braskerud’s (Norway) feedback on the presentation: Bent used to work with constructed wetlands to capture Nitrogen, Phosphorous and pesticides, in 1992-2005 in Norway. There are reports available on this on internet.  These studies were also interesting to the Limburg WA.

Presentation from Solutions in Slovakia (available as PPT)

For ca 25 years Michal Kravčík and his colleagues have been working on developing a water management system based on the principles of permaculture and the Ecosystem Approach. These principles include that the rain needs to be captured with a variety of measures, for example, check dams, reduce erosion, etc. and that nature can create more water sources both faster and cheaper than any man-made system.  

In Slovakia, land use has changed both in rural and urban areas, increasing drainage and water runoff and creating heat islands. This land use change was driven by the development of industrial agriculture which has reduced diversity and introduced monocultures. Reduction of water capturing elements has created a situation with faster runoff to valleys causing floods, increasing erosion processes, reduction of organic soil content (and thus reduction of its capability to retain water and fertility) and a drop in underground water levels. In urban zones, paving, roads and buildings prevent infiltration and channels the water, increasing fast runoff of rainwater and creates floods. At the same time, reduced green areas have increased urban heat islands. [See e.g. this paper in nature on greenery as a mitigation and adaptation strategy to urban heat]. This is because evapotranspiration and evaporation of water is demanding energy, which cools the air. On infra-red images of the city, forest is dark (cooler) and stone surfaces red (warmer) - see the attached presentation.

Studies have shown that ca 37 000 billion cubic m of rainwater is lost globally from land use changes providing a contribution to sea level rise. In Europe the trend is of increased runoff, decreasing of infiltration, and decreasing water vapor to atmosphere, causing a historical drying out, providing risks for production in agriculture, and industry. This "de-watering" of the landscape also creates desertification, on one hand, and floods on the other hand.

Michal and his colleagues published a book in 2007 on the concept of a New Water Paradigm (NWP) developed in Slovakia. This focuses on water retention measures, how to change from drylands to green lands – a whole system of manage rainwater. It addresses the problem that water is often not infiltrated to the soil. By increasing of rainwater harvesting to the ecosystem, increasing infiltration to the soil, to the ground water, the small water cycle can be regenerated. This approach was adopted in Slovakia in 2010 at government level: “Landscape Restoration and Integrated River Basin Management Program for the Slovak Republic”. 

(*) The small water cycle: The small water cycle over land is a closed circulation in which water evaporated from land falls in the form of precipitation over the same terrestrial environment. The small water cycle is more important to local precipitation patterns than the large water cycle. Read more on it here.

New Water Paradigm (NWP) vs Old Water Paradigm

Old water paradigm

New water paradigm

Protects surface water as the main source and reserve of water

Protects groundwater and soil water as the main treasure of water

Rainwater is an inconvenience, needs to be quickly removed

Rainwater is an asset that needs to be retained (especially in soil/plants)

Soil sealing has minimal impact on the water cycle

Soil sealing has a fundamental impact on the water cycle

Soil sealing has minimal influence on global warming

Soil sealing may be important factor in global warming

Land use changes creating extreme weather

The breakup of the water cycle over the landscape also increases climate extremes. It was emphasized that the increase of hazards in Europe is due to land use changes and not mainly from climate change. With decrease of natural ecosystems, the sensible heat is increasing, and evapotranspiration is reduced. The result is large-scale heat islands, that affect the spatial changes in precipitation distribution, with a resulting increase in extremes of weather. Globally such changes include a significant decrease of rainfall in drier areas, with dramatic increases of precipitation in colder regions. Powerful storms cause large volumes of moist air rise rapidly in a constrained region leading to intense condensation leading to both rapid and localized extreme rainfall [see e.g. Makarieva et al. 2013 and Michal Kravic and Lambert]

According to Michal, the same changes in land use around Limburg impacting on atmospheric vapor flows, has resulted in the changes in evapotranspiration extreme rainfall and runoff. [In the Netherlands there are studies indicating that increased urban land use has influenced extreme precipitation. ] 

There is also a link between drought and intense downpours, a phenomenon scientists have named “flying rivers”. [ “Atmospheric rivers“ in frontal system also have a role to play for creation of extreme rainfall and flood events, see e.g. this paper.]  

In Slovakia the water deficit and an overheated landscape have also results in a phenomena also changing the distribution of rains, where mountains and forests receive more heavy rains, and more annual precipitation, and lowlands, including wetland, agricultural and urban areas receive less, becoming increasingly semi-arid. The reasons for this are found in changes in evapotranspiration and water vapor flows, explained by the bio pump theory, and the second thermodynamic law, where air flows from warmer to colder zones.  Although there are many insecurities and lack of specific studies for Europe, the “biotic pump” is promoted by several research groups around the world. There was some discussion on the evidence for the extreme weather (such as in July 2021) being caused or influenced by changes in water vapor flows due to land use changes. What the Slovak experts have discovered for their own area in terms of land use influencing rainfall patterns, could be valid also for the rest of Europe and this event. 

The biotic pump theory describes how areas with high evaporation creates low pressure zones which draw in air. Regions with more leaf area (with more evaporation and evapotranspiration are thus expected to attract winds from areas with lower leaf area.  This means that sufficiently large areas of tree cover actively draw in air and moisture from elsewhere. Therefore, large continental regions such as Amazonia, the Congo and Siberia remain so wet. [This video is explaining the biotic pump, conceptualized by Makarieva and Gorshkov 2007, also described here by Douglas Sheil in 2018]. However, it also means that deforestation and reforestation impacts water vapor flows. Even smaller patches of vegetation have shown to increase the water holding capacity in areas such as the Sahel, by creating smaller water cycles and thus enabling rainfall to "travel" further inland. Supporting the smaller water cycle (*) can thus reverse desertification.

Discussion

Measures involving farmers: incentives and policies

The Limburg Water Authority asked how the Slovaks can say the measures are cheap, while changing large scale agricultural systems are in fact expensive.

Slovaks suggested that farmers ought to play a more important role in capturing the water, and rainwater harvesting on their land. The (EC) common agricultural policy is an important instrument here, to improve water in the soil. Such a policy can be supported by estimates of how much runoff an area will have from heavy rains, and the benefits of water retention. Such benefits include vapor to atmosphere, water in soil, decrease of heat, creating of water resources, tons sequestration of carbon, and the costs. How much water is runoff from each community and how everyone is responsible to capture it was done in the Horizon 2020 project SIM4NEXUS led by the Slovak experts. 

In the Netherlands – in the rural environment there is no public policy to retain the water on the land. However, a policy has recently been approved that will support farmers to include more natural elements in the landscape for water retention. (More info will follow on this policy).

Changes in land use of rainwater system to a new water paradigm would be needed in Europe overall to have an effect on water vapor flows. Michal (Slovak): However, Europe has not been taking this up, but we are open for collaboration to work on this issue further. It would be a big challenge for Europe to implement such common policies and practices, but it would also have common benefits.

Check dams and other physical measures

Bent (Norway): A delegation from Norway visited Michal and his colleagues a few years ago, and we saw a lot of check dams and it was convincing what did work and what did not work. A few months ago, we did our own first check dam in the forest, as a test in the forest around the Oslo. In Norway slopes are all over, and not so much space available for check dams. They also capture sediments which is very useful. The first dam we did took 3.5 hours, by two people.

Question: what happens to the biodiversity when building a check dam? Reply: the original stream runs under it. It is only when it is pouring down that its function is really used.

Anne (Limburg): I am really interested in how you did it on the wooden dams. But how safe is it and can it really work in high floods?

Michal (Slovak): Our experience – the first check dam was built 26 years ago and last week I was there to see and it is still working. It is a beautiful place. It is also important for the microclimate. I am exchanging experiences with Australia, and they have the same experience. One place was built on agricultural land, 20 years ago, and now it is functional and no local flooding which was there before.

Peter (Slovak): if you want to play it safe, start from the top of the catchment – reducing the impact of the worst events. Start on dry areas, on infiltration swales. Don’t build big but build more. If it lasts for 2-3 years, it will work forever. This is because the dams will trap sediments, and the sediment attracts vegetation and making the dam more robust and resilient. Start learning from someone who already did it and has experience. You cannot model everything; it is partially art.

Anne (Limburg): I understand you want to be invited to the Netherlands!

Landscape approach is key

Michal: We collaborate with the Slovak Department of Agriculture, and Demokritos [The National Center for Scientific Research] in Greece and Ministry of Environment in Greece to restore damaged landscapes. The most scientific projects are oriented to evaluate, but in the future we need to focus on reversing the degradation. A landscape approach is key for adaptation, including water resources, agricultural land, capacity, prevention of food crisis and prevent heavy storm, fires etc.

(Payment for) ecosystem services

Financial tools for landscape restoration is needed. The absence of such tools is a big challenge for implementation. In the South of Limburg, the soil is very fertile, and land is very expensive. Farmers therefore need to grow cash crops to compensate for the expensive soil. However, these conditions are also used as arguments not to change anything. 

Michal: A solution is that farmers could be compensated to sequestrate C (carbon). A big challenge is to find solutions of water retention measures and carbon sequestration to the soil flowing to the root system. Plants produce CO2 and need to sequestrate C. 1 m3 of biomass, needs 1.4 tons of CO2 and in every ton of biomass is 400 kg of carbon. We need financial tools and a carbon policy to support compensation to go to farmers for sequestration of carbon, which also increase water retention measures. In that way it would be interesting for farmers to plant trees, which would support water retention. However, farmers do not know about this concept. 

In Limburg they don’t work with the ecosystem services concept, but they work with farmers to change their soil management system.

Deforestation leading to soil erosion

Already Plato referred to the role of deforestation to soil erosion. He here describes the situation before deforestation in Greece: “Moreover, the land reaped the benefit of the annual rainfall, not as now losing the water which flows off the bare earth into the sea, but having an abundant supply in all places, and receiving it into herself and treasuring it up in the close clay soil, it let off into the hollows the streams which it absorbed from the heights, providing everywhere abundant fountains and rivers….” (Platón, Kritias).

Norwegian storm water policy

Bent explained the Norwegian approach to (urban) storm water in Oslo, which is based on a three-step approach. Every new building must take care of step 1 and step 2. Most of the city is already built – and therefore people need to participate. They have done citizen panels and are starting up a new project with cultural researchers to help people understand. This policy is described here

Follow up:

Another exchange will be arranged in January between the three countries, focusing on urban (nature based) solutions.

The WAC will also investigate further:

  • How to encourage (finance) measures in the landscape to reduce floods? 
  • The landscape restoration approaches
  • Scope the possibility to continue this exchange also involving a network that WAC is supporting in the Horn of Africa.
  • Forests as biotic pumps to reverse land degradation.

Participants:

Experts from Limburg Water Authority

  • Anne Buit, Innovation manager, Limburg Water Authority
  • Marco de Redelijkheid, advisor at the Limburg Water Authority
  • Bas Majolee, Technical manager, Limburg Water Authority.
  • Bas Rompelberg, Water adaption in agriculture, Limburg Water Authority.
  • Maurice de Wit, Technical project manager, Limburg Water Authority

Slovak experts:

  • Michal Kravčík, water manager, engineer
  • Peter Gabris, retired computer programmer and hydrologist

Norwegian expert:

  • Bent Braskerud, Chief engineer, Oslo municipality

Global Center on Adaptation (knowledge broker):

  • Åse Johannessen, PhD, Facilitator Water Adaptation Community, Global Center on Adaptation, GCA

Questions

The Limburg Water Authority had sent some questions to the group which they were interested in finding more information about:

  • What are the problems in Slovakia?
  • What kind of measures are you taken against water problems and climate problems?
  • Who is responsible to deal with water - and climate problems?

Specific about nature-based solutions:

  • Where do you practice these solutions and what are technically important things to consider?
  • What is in your point of view the reason to choose for these options?
  • What is the point of view versus ecological values?
  • Do you have any quantified results of these solutions?
  • How is the impact of maintenance/ robustness of the construction?