Understanding Sediment
Sediment losses
Everyone benefits when our precious soils remain on the land where they belong. Sediment losses from the land have a wide range of negative effects on both freshwater and estuarine ecosystems. Sediment degrades habitat and water quality including:
- The water column, by increasing turbidity and levels of suspended sediment, and reducing visual clarity (how far animals and fish can see) and euphotic depth (how far sunlight can penetrate the water).
- The seabed increases the muddiness of the seabed and, as sediment accumulates, the rate at which the water gets shallower.
Affecting communities
Sediment also affects the communities living, working and recreating in waterways flowing into the harbour as well as the harbour itself. Siltation of the waterways affects:
- Recreational values – due to lower quality water for swimming and other purposes).
- Customary rights – for example, through a reduction in the ability to gather kai moana or provide for visitors to a marae.
- Economic returns – as the health of the Kaipara Moana and its catchment are intrinsically linked with the ability to continue making productive use of local fisheries and aquaculture resources.
The catchment
The Kaipara Moana catchment spans 600,000 hectares across both Northland and Auckland, including seven major rivers and large areas of farmland and erosion-prone land.
KMR supports projects across the catchment, from river headwaters to the harbour, ensuring the benefits of a healthy, thriving Moana are shared by all.