Double Drainage for Fresh Water: from Idea to Application

Water for agriculture
The Netherlands

Agriculture in the Dutch province Zeeland relies for fresh water in many cases on rainwater and fresh groundwater in areas such as dunes and creek ridges. Shortage of fresh water remains a recurring challenge. In the project ‘Working together for Freshwater: demonstrating, monitoring and evaluating innovative drainage’ a new idea of double drainage has been tested in practice. The results are promising.

Double drainage: drains are superimposed to drain salt (left) and fresh water (right) separately.

Key Takeaways

  • Double drainage is an innovative technique for harvesting fresh water for agricultural practices; drains are superimposed to drain salt and fresh water separately.
  • By capturing fresh water via double drainage during wet periods, farmers can utilize a new source of fresh water. Essential in a region with structural fresh water shortages.
  • Monitoring shows that double drainage effectively separates salt and fresh water, offering a proof of concept and providing scope for further optimization.
  • Collaboration and funding are essential to the success of this innovative development. The project was a collaboration between governments, water experts and farmers.

Project Details

Started: 2021 – Completed: 2024
Ref: 251638 | Status: Completed
Title: Samenwerken voor zoetwater: innovatieve drainage demonstreren, monitoren en evalueren

Background

The idea of double drainage came from the son of a farmer. Would this concept work in practice, he was wondering. After an exploration, the conclusion was that this application has not yet been applied anywhere.

In this concept, drains are placed exactly one above the other and connected to a separate collector. This separates the discharge of salt and fresh water. Fresh water can then be collected via the shallow drainage during wet periods. The deeper drainage captures the salt groundwater that is coming to the surface. Thus, fresh water is harvested!

This project is follow-up to the completed project “Working Together for Fresh Water”, whose main conclusion is that drainage and infiltration techniques can be used to harness much more fresh water in the subsurface.

Activities

The model of the innovation was computed through simulations and the outcome was, in theory it could work. This outcome was the spark for this demonstration project. And now the idea has been applied in practice at two locations at agricultural farms in Zeeland.

In this project an anti-salination drainage has also been tested at a third location, because this type of drainage is still little used in this region. And there is a desire to gain more experience with this technique.

Acacia Water advised on the construction and design of the double drainage system. The monitoring of the water coming from the drainage system is done together with Deltares. Measured were the ratio of salt to fresh water, groundwater level, soil moisture and DUALEM for terrain conductivity.

Findings

Initial results from the study show a clear difference in salinity from the different drains in the case of the double drainage. It is the basis for a valid assumption that the double drainage system works. This is an important step towards further optimization of double drainage and the development of a new source of fresh water for agricultural businesses.

From the results of this project, key figures and guidelines for construction, management and maintenance are also being developed. These practical data will provide more insight into the operation and efficiency of this solution.

Project Areas

The location of this project is the island of Schouwen-Duiveland in the Dutch province Zeeland on test plots of two arable farmers in Kerkwerve for double drainage and a test plot in Dreischor for anti-salinization drainage. The sites in Kerkwerve are characterized by low-lying pool soils with high seepage pressure and a shallow layer of unripened clay. The plot in Dreischor is located on slightly higher ground with greater drainage and deeper layer of unripened clay.

These sites were chosen because of their representativeness for different soil and hydrological conditions within Zeeland.

Geographic scope: Local

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Kerkwerve

Project location.

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Dreischor

Project location.

Downloads and Links

No downloads or links are available.

In Cooperation With

Commissioned by:

European Commission

Funded by:

European Commission Provincie Zeeland Gemeente Schouwen-Duiveland

Project partners:

Acacia Water Rusthoeve AIKC Deltares Rusthoeve AIKC

Contact

Arjen Roelandse

Hydrologist

+31 6 15 19 86 20
arjen.roelandse@acaciawater.com
arjenroelandse

Related topics

Drainage, Freshwater harvesting, Salinization

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