Two-stage ditches in Sweden

Last changed: 14 April 2021
A person by a ditch, photo.

Eutrophication of the Baltic Sea is expected to increase with more extreme weather events in the future. One solution can be two-stage ditches that may reduce nutrient and sediment losses from upstream soil and waterways, as well as reduce the risk of flooding and increase water retention. In this project we evaluate the efficiency of two-stage ditches.

Combating eutrophication requires decisive mitigation measures aimed at reducing agricultural losses of nitrogen (N) and phosphorus (P) from field sources to aquatic systems. This need becomes critical in light of future change which is likely to further accelerate N and P pollution due to increased flashiness of changing climate and growing food demand. However, our scientific understanding of hydrochemical and biogeochemical processes in agricultural streams is still lacking.

Two-stage ditches to reduce losses of nitrogen and phosphorus

Our project will advance the knowledge of these processes in agricultural streams in Sweden and show how this knowledge can be applied to effectively combat eutrophication. We will focus on two-stage ditches which are new type of mitigation measures aimed at increasing water retention and reducing losses of N and P.

A ditch by agricultural land, photo.
A two-stage ditch at Ståstorp. Photo: Lukas Hallberg.
A ditch with leaves and grass around by a farmland, photo.
A two-stage ditch at Torpsbäcken. Photo: Lukas Hallberg.

An improved environemental function?

We will show how hydrochemical and biogeochemical processes affect two-stage ditches’ effectiveness in retention of water, N and P and how proper placement, design and management of two-stage ditches can enhance their ecosystem functions (self-purification, erosion and flood prevention). We hypothesize that two-stage ditches provide improved environmental function compared to traditional narrow and trapezoidal ditches, with a single aim to remove water from the drained agricultural fields.

This project brings together hydrochemists, biogeochemists and stakeholders, all focused on understanding and reducing eutrophication.  

Facts:

The project is led by Magdalena Bieroza. Lukas Hallberg is a PhD student in this project that is financed by Formas, Stiftelsen Oscar och Lili Lamms minne and HaV.

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