Hydrography Data

This dataset defines the Mean High Water coastline of New Zealand and offshore islands at a scale of 1:50,000, and describes the type of coast along the coastline, for example, steep coast, mangrove, or stony shore.

Purpose
The NZ Coastline – Mean High Water dataset is the first step towards improving the national coastline data for New Zealand. LINZ is currently working on a long-term project, “Coastal Mapping” to capture a range of national coastlines derived from LiDAR and bathymetry. This will enable us to generate coastlines, for example, for Mean High Water Springs, Chart Datum and Highest Astronomical Tide. The project is currently focused on capturing LiDAR and bathymetry data, and the timeframe for delivering the new coastlines will be established once the data capture has progressed.

Status
This dataset was created and is maintained from LINZ Hydrographic and Topographic sources. Originally created in August 2020, this dataset will be replaced by a more accurate dataset once data becomes available through the Coastal Mapping project.

Data sources and preparation
The spatial coastline data (1:50,000 scale) is sourced from the Topo50 series where it is described as a line forming the boundary between the land and sea, defined by mean high water. The source polygon data has been broken up into line segments to enable a coastal classification to be attributed to each segment of coast. Coastal classification data is based on official Electronic Navigational Charts published by the New Zealand Hydrographic Authority. Not all segments have been assigned a coastal category.

APIs and web services
This dataset is available via ArcGIS Online and ArcGIS REST services, as well as our standard APIs.
LDS APIs and OGC web services
ArcGIS Online map services

This provides a polygon coastline and islands layer which is based on the Topo50 products. It is a combination of the following layers:

• NZ Coastlines (Topo 1:50k)
• NZ Island Polygons (Topo 1:50k)
• NZ Auckland Is Island Polygons (Topo, 1:50k)
• NZ Campbell Is / Motu Ihupuku Island Polygons (Topo, 1:50k)
• NZ Antipodes Is Island Polygons (Topo, 1:25k)
• NZ Kermadec Is Island Polygons (Topo, 1:25k)
• NZ Bounty Is Island Polygons (Topo, 1:25k)
• NZ Snares Is / Tini Heke Island Polygons (Topo, 1:25k)
• NZ Chatham Is island polygons (Topo, 1:50k)

This topographic coastline is the line forming the boundary between the land and sea, defined by mean high water.

Islands from the NZ Island Polygons layer that lie within the NZ Coastline and Chatham Islands areas (i.e. islands in lakes, rivers and estuaries) have been removed.

The GIS workflow to create the layer is:

1. NZ Coastlines were converted from a polyline to a polygon using a polyline to polygon tool.
2. The resulting coastal polygon was then used as an input into an erase tool and run against the NZ Island Polygon layer to remove all islands lying within the NZ Mainland and Stewart Island.
3. This was then merged with the NZ Chatham Is island polygons (Topo, 1:50k) that have had the islands within the main island polygon removed, NZ Auckland Is Island Polygons (Topo, 1:50k), NZ Campbell Is / Motu Ihupuku Island, NZ Antipodes Is Island Polygons (Topo, 1:25k), NZ Kermadec Is Island Polygons (Topo, 1:25k), NZ Bounty Is Island Polygons (Topo, 1:25k) and NZ Snares Is / Tini Heke Island Polygons (Topo, 1:25k) layers using a merge tool.

For more detailed description of each layer refer to the layer urls above.

APIs and web services
This dataset is available via ArcGIS Online and ArcGIS REST services, as well as our standard APIs.
LDS APIs and OGC web services
ArcGIS Online map services
ArcGIS REST API

A submarine object over which the water is shallow, which is detached from the shore and whose bottom is visible at low water; may be a menace to navigation on the surface

Data Dictionary for shoal_poly: docs.topo.linz.govt.nz/data-dictionary/tdd-class-s...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50

A channel which carries surface water.

Data Dictionary for drain_cl: docs.topo.linz.govt.nz/data-dictionary/tdd-class-d...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50

A natural, flowing body of water emptying into an ocean, lake or other body of water and usually fed along it's course by converging tributaries.

Data Dictionary for river_cl: docs.topo.linz.govt.nz/data-dictionary/tdd-class-r...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50

The line forming the boundary between the land and sea, defined by mean high water.

Data Dictionary for coastline: docs.topo.linz.govt.nz/data-dictionary/tdd-class-c...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50

An artificial open waterway used for transportation, waterpower or irrigation.

Data Dictionary for canal_poly: docs.topo.linz.govt.nz/data-dictionary/tdd-class-c...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50

An artificial open waterway used for transportation, waterpower or irrigation.

Data Dictionary for canal_cl: docs.topo.linz.govt.nz/data-dictionary/tdd-class-c...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50

Coastal rocks; rocks between high and low tide

Data Dictionary for rock_poly: docs.topo.linz.govt.nz/data-dictionary/tdd-class-r...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50

An isolated rock or rock formation between high and low tides.

Data Dictionary for rock_pnt: docs.topo.linz.govt.nz/data-dictionary/tdd-class-r...

This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.

Further information on Topo50:
www.linz.govt.nz/topography/topo-maps/topo50