Farm Drains & Ditches
Drains and ditches are important as we use them to get water off our land, so that we can farm it. However, it is these very drains and ditches that are moving nutrients and contaminants quickly into our waterway systems.
Learn about all the different types of drainage ditches and how each one can offer a unique approach to mitigating the loss of contaminants into our waterways.
In depth overview of drains and ditches
If you would like to find out more about different drainage ditch water quality practices, watch the following video.
Nathan Burkpile from New Zealand Landcare Trust discusses how different types of ditches and drains can be used to improve water quality. [20 mins]
Re-planning drains & ditches to mitigate nutrient loss
Below are some examples of drainage ditch mitigations that can be implemented to help intercept the water to remove the nutrients before it enters the main waterway.
In-ditch wetlands
It is important to determine the levels for an in-ditch wetland to ensure adequate drainage and water levels to encourage growth of emergent vegetation. To establish wetland plants for in-ditch wetlands it is important to create a shallow water habitat of about 200 – 300mm.Planting is done in the middle and along the edge of the in-ditch wetland using native sedges .
Re-battering farm ditches
Widening an existing ditch to encourage growth of wetland vegetation to remove nutrients can be done by re-battering the sides of a ditch. This stabilises the banks of the ditch, reducing erosion. By planting native vegetation, sediment from surface flows creates a filtering effect. Whislt the wider drain allows for the establishment of emergent vegetation, adequate paddock drainage for production is still maintained.
Grass swales
Grass swales allow for the reduction of sediment and nutirents flowing from the paddocks. These grass swales can be grazed during the dry season but should be left high during the wet season.
