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Managing Your Waterways: Fencing & Planting Riparian Areas

24-May-2016 | Contributed by: Geoff Prangley

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Masterton River Bank

Riparian areas, or waterway margins, are the strip of land that runs alongside waterways. If you have any waterways on your land, managing your riparian areas is something to consider. It may take a bit of work up front, but it can have benefits for your land, your livestock, and for the surrounding area’s environment. Farmer can now deduct the expense of riparian planting as an operational expense.

Why you should manage your waterway margins

Managing riparian areas will:

  • Prevent livestock from entering the waterways and contaminating the water
  • Prevent erosion – both natural erosion, and erosion from livestock trampling the area
  • Prevent stock and fertiliser runoff

The benefits of planting:

  • When planted right, the plants roots will help prevent erosion
  • Plants can provide extra fodder for livestock
  • Water quality will improve as plants filter pollutants and control flood flows
  • Planting will provide habitats for wildlife 

Managing your riparian areas

Management can be divided into two areas – fencing, and planting. These two management techniques, work best when used together, especially if you keep livestock near the area, but can be used individually.

Assessing your riparian areas:

You’ll need to identify your waterway’s water levels in order to fence or plant the area. Take note of:

  • The stream edge
  • Wetlands
  • Any slopes, and their steepness
  • Where regular floods levels lie
  • Where annual flood levels lie
  • Any extreme flood levels
Fencing riparian areas: 

Depending on what you use the surrounding land for, and your budget, fencing your riparian areas may be the cheapest, and simplest option. Fencing should always be considered if you keep livestock near your waterways.

If you have temporary livestock in surrounding paddocks, you may only need a temporary electric fence to block off the riparian areas. You can adjust your fencing to suit the season, moving it to suit flooding.

If livestock will be permanently in paddocks surrounding the riparian area, you will need to place the fence five metres from the flood zone, unless you are prepared to move it regularly.

Fencing is a good minimum option for those with livestock who have a low budget. It will prevent livestock from contaminating the waterways and will prevent them eroding it. However, without planting, it will not completely prevent runoff, slow flood flows, or prevent natural erosion.

When combined with planting, both methods can also allow for extra plant fodder. Native fodder trees can be planted over the fence’s edge, allowing livestock to graze from them without entering the riparian area.

Planting riparian areas:

If you do not have livestock near your waterways, riparian areas still need taking care of, particularly if you have crops nearby as fertiliser runoff can pollute the waterways. Regardless, planting will help control the waterways flood area, prevent natural erosion, and will improve water quality – which is important, even if you just want to allow your kids to go for a swim in the river.

Planting of riparian areas should be at least 5-10 metres wide. A planting plan should be create to allow for how much space individual plants require. When planting, consider the time of year. You’ll want to plant them so they have time to establish before the dry summer comes around, but any frost sensitive species will need to be planted in early spring.

Plant types need to be divided up into areas you took note of during your assessment of the riparian area:

The stream’s edge – This area runs from the stream’s edge, just up to regular flood areas. This area has high levels of moisture. Plants should have flexible stems and branches to move with any flood waters.

Suitable plants for this area include:

  • Carex
  • Coprosmas
  • Ferns
  • Marble leaf
  • Mikimiki
  • Manuka
  • Rushes
  • Sedges
  • Toetoe
  • Tussocks

The lower bank – This area copes with variations in moisture, as it is subjected to regular flooding. Erosion is a problem in this area, and plants with fibrous root growth can help prevent this.

Suitable plants for the lower bank include:

  • Carex
  • Coprosmas
  • Cabbage tree
  • Five Finger
  • Flax
  • Kohuhu
  • Koromiko
  • Kowhai
  • Manuka
  • Toetoe
  • Wineberry

The upper bank – With less chance of flooding, taller plants can cope well in this area. Native fodder trees can be planted on the edge of this area, overhanging fences, to provide extra fodder for stock.

Suitable plants for the upper bank include:

  • Ake ake
  • Broadleaf trees
  • Cabbage tree
  • Golden ake ake
  • Kauri
  • Kohuhu
  • Koromiko
  • Kowhai
  • Lancewood
  • Poplar
  • Ribbonwood
  • Tagasaste (tree lucerne)

Wetlands – You may also have wetland areas on your property from your waterway. These areas are permanently wet, so plants will need to be able to tolerate high moisture levels all year round.

Suitable plants for wetlands include:

  • Cabbage tree
  • Carex
  • Ferns
  • Flax
  • Mahoe
  • Manuka
  • Mingimingi
  • Pukatea
  • Seven Finger
  • Swamp maire
  • White pine

Maintaining riparian areas:

Once your plants are in, you’ll need to keep an eye on their health, and weed as required. Check fences and ensure they are maintained too, and if you have any fodder trees, make sure their growth does not affect the fence lines.

If any plants do not take to the area, make sure you replace them. Pest control may also be necessary. 

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