Post-quake sediment success on Kaikōura Plains

Using common farm items, the Kaikōura Plains Recovery Project (KPRP) team found an innovative method to control sediment and nutrient runoff during drainage works at a demonstration site.

The KPRP team worked with Aqualinc Research Ltd. to develop some cost-effective, innovative and practical solutions which prevented more than 90% of sediment and nutrient material entering the receiving waterway during drainage work.

Justin Legg, MHV Water Senior Hydrogeologist - Kaimātai Wainuku Matua*, said taking the time to think about how to solve the problem was the key.

“We knew that we couldn’t retire the whole area of land – it comes down to balancing the protection of both farming and the environment.”

By taking some time – the team was able to find a method that could achieve both.

Method adopts 'number 8 wire' mentality

“All we did was dig a trench, put a pool at the bottom and added some hay bales to slow the water down, filtering out the silt and sediment.

“It seems really simple – and it was. The results speak for themselves. It was all about utilising the resources and the farmers knowledge of their land that led to it,” Legg said.

KPRP Project Manager Jodie Hoggard said they really wanted to find a simple, cost-effective method that used everyday items found around the farm, or easy to access, but that would make a big impact.

Filtering sediment during drainage works

Filtering sediment during drainage works reduces sediment and nutrient runoff from entering local waterways.

“Number 8 wire kind of stuff, that would align with industry agreed Good Management Practice (GMP),” she said.

Using simple things like haybales, waratahs and cloth available from general farm retailers (or roading contractors), the project team found that by lining the end of the drain with cloth covered haybales and staking the bales into ground, the ‘sediment trap’ reduced more than 90% of the contaminants entering the waterway from the drain.

“Without any real industry-led examples for sediment control during works on-farm, we hatched the method together on the fly but realised it’s actually something that could be adapted for most farm drainage work situations.

“We found there was plenty of information on sediment control in developments and road construction, but nothing really logical for on the farm,” Hoggard said.

Key to success for sediment management

Showing the benefits of simple sediment control methods during drainage works

Showing the benefits of simple sediment control methods during drainage works.

Legg says sediment management doesn’t have to be complicated or expensive.

  • Stop and think about the problem – what have you got on hand that could be useful?
  • Ask questions – people like Jodie Hoggard and Makarini Rupene (Environment Canterbury Pou Mātai Kō/Cultural Land Advisor) are there to help. If they do not know the answer, they will know where to find it.
  • Take photos or give someone a call – often it is time that costs money and often all that is needed is a conversation and a photo sent for context.
  • Talk to your neighbours, grandparents, past owners – find out about the land and map the area based on local knowledge. It will help you in the long run.
  • Do not be scared – it is not going to cost you lots and no one is going to tell you you’re doing it wrong. People are more than willing to help – you just need to ask.
  • Think about planting – protecting farming and the environment goes hand in hand. If you find out what plants are going to work more sustainably based on your land, you are going to tick all the boxes. Environment Canterbury Pou Mātai Kō/Cultural Land Advisors will be able to help you through this process.

Finding the right drainage solution

Drainage can be used to maximise the production and general health of land and fits with industry-led/agreed GMP guidelines, which help farm owners and managers work the land with long-term sustainable practices in mind.

“We encourage all farmers who are thinking about drainage to always ask "is drainage the right and/or only solution" before making any plans,” Hoggard said.

“There is not a ‘one-size-fits-all’ solution to wet paddocks – it’s about finding the right one that works in that specific area,” she said.

If you are thinking about drainage, contact Environment Canterbury or check out the sediment success resources online.

Find out more about KPRP

The Ministry for Primary Industries funded Kaikōura Plains Recovery Project (KPRP) has been supporting Kaikōura farmers since the 2016 earthquakes to understand the new (much wetter) landscape they are working with.

The Project will be wrapping up over the next few months. Alongside drainage work, it has has focused on whole catchment recovery.

See Project resources, plans, methods and results on our Project page.

Related documents:

*Legg is a previous employee of Aqualinc Research Ltd.