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Managing Erosion and Sediment Loss

Erosion and sediment loss are natural processes, but they can be significantly accelerated by land use activities. When soil is lost from land and carried into waterways, it reduces land productivity and affects the health of streams, rivers, estuaries, and coastal environments.

Managing erosion and sediment at the source is one of the most effective ways to protect soils, maintain productive land use, and support healthy freshwater from hills to the sea (ki uta ki tai).

What Is Erosion & Sediment Loss

Erosion occurs when soil is detached and moved by water or gravity.

Sediment loss refers to the transport of this soil into waterways.

Erosion may be triggered by:

  • heavy or prolonged rainfall
  • steep or unstable geology
  • loss or reduction of vegetation cover

It can be accelerated by land‑use activities such as:

  • vegetation clearance
  • intensive grazing or cropping
  • forestry harvesting
  • earthworks
  • construction and use of tracks and roads that expose bare soil

Hill Country Erosion in NZ

Impacts of Erosion & Sediment

Uncontrolled erosion and sediment loss can have multiple impacts, including:

  • loss of topsoil, reducing soil fertility and productive capacity
  • sediment entering waterways, degrading water quality and aquatic habitat
  • damage to streambanks, fencing, and farm infrastructure
  • increased flood risk from sediment build‑up in rivers
  • reduced land stability for farming, forestry, and housing

Preventing erosion helps protect both rural land and downstream environments.

Erosion Types in the Nelson Region

The main forms of erosion affecting rural land in Nelson include:

  • Soil slips and surface erosion on hillslopes, often during high‑intensity rainfall or following prolonged wet periods
  • Streambank erosion, particularly where stock access or lack of vegetation reduces bank stability
  • Land‑use related disturbance, such as exposed tracks, cultivated ground, earthworks, or recently harvested forest areas

Much of the steepest land in the region remains under indigenous or plantation forest, where woody vegetation provides important protection. However, unfenced or disturbed streambanks on pastoral land remain vulnerable to erosion and sediment loss.

What We Do

Nelson City Council supports erosion and sediment reduction through:

Council works alongside landowners to identify practical, locally appropriate solutions that protect land and waterways.

EPA speaking with a landowner near a landslip on their property

What Can You Do

Rural landowners can help reduce erosion and sediment loss by:

  • identifying erosion‑prone areas on their property
  • protecting or restoring vegetation cover
  • fencing stock from vulnerable areas
  • working with neighbours at a catchment scale
  • exploring funding and planting support
  • talking with Council early about erosion concerns

Small actions across many properties can deliver significant benefits across the catchment.

Contact the Environmental Programmes Advisor to discuss options - healthy.streams@ncc.govt.nz

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