Estuaries spatial database

Introduction

The New Zealand estuaries spatial database is an interactive map that allows you to explore data related to estuaries, rivers, river catchments, and the marine environment.

New Zealand estuaries spatial database.

Use the drop-down menus and tick boxes to display the information you’re interested in.

Some examples of the maps you can create include:

  • seagrass extent and coastal turbidity
  • wetlands and protected areas in vulnerable catchments
  • estuary eutrophication as measured by chlorophyll, river water quality total nitrogen, and natural river and stream cover
  • inanga spawning sites and natural river and stream cover.

Data layer descriptions and sources

In this section:

Water quality, sediment and river flow

Estuarine and coastal water quality

Indicators of ecosystem health are monitored nationwide to assess the state and trend in estuarine and coastal water quality. The indicators are:

  • chlorophyll-a
  • visual clarity
  • dissolved oxygen
  • dissolved reactive phosphorus
  • Enterococci
  • faecal coliforms
  • ammoniacal nitrogen
  • nitrate-nitrite nitrogen
  • suspended solids
  • total phosphorus, and
  • total nitrogen and turbidity.

Water quality state is the median value, in milligrams per litre, for 2013–2017. Water quality trend is the change in each variable (2008–2017) and stated as ‘improving’, ‘worsening’ or ‘indeterminate’.

Source: Local and regional councils. Managed by Stats NZ and the Ministry for the Environment.

Coastal sediment heavy metal load

Concentrations of zinc, lead, copper and cadmium in coastal and estuarine sediment are provided from across 13 regions from 2015 to 2018. The metal concentration is reported as mg/kg dry weight and compared with the default guideline values (DGV) and upper guideline values (UGV) for toxicants in sediment. Results are classed as above DGV, below DGV and not applicable.

Source: Local and regional councils. Managed by Stats NZ and the Ministry for the Environment.

River nitrogen state and trends

Total nitrogen, nitrate-nitrogen and ammoniacal nitrogen levels are monitored at selected river sites. The median values from 2013 to 2017 were calculated to measure the state of river water quality.

River water quality trends were calculated for 10 years (2008–2017), 20 years (1998–2017) and 28 years (1990–2017) and categorised as very likely improving, likely improving, indeterminate, likely worsening and very likely worsening. River water quality monitoring data was collected by NIWA and regional councils using consistent time periods and comparable methods.

Source: NIWA, managed by Stats NZ and Ministry for the Environment.

River observed and predicted streambed sedimentation

The percentage cover of fine streambed sediment was recorded for 10,026 sites from 1990 to 2011 (1970–2011 in Fiordland). These values were used to model the streambed sedimentation across New Zealand. Fine sediment is particles of sand, mud and silt that are smaller than 2 mm in diameter. 

Source: Manaaki Whenua - Landcare Research, managed by Stats NZ and the Ministry for the Environment.

River flow

River flow in 485 rivers was measured over 5 years and used to model flows for every river. Mean river flow, over 5 years or more, is expresses in cubic metres per second (cumecs).

Source: NIWA and regional councils. Managed by Stats NZ and Ministry for the Environment.

Catchment and land cover

Vulnerable catchments

Includes all river and stream catchments that are classified as vulnerable. Vulnerable means showing signs of stress but have not yet reached a tipping point, where it becomes much more costly and more difficult to return water bodies to good health.

Source and management: Ministry for the Environment, see Freshwater Improvement Fund. 

Sea-draining catchments

Includes all river and stream catchments that drain to the in the River Environment Classification database.

Source: Freshwater Ecosystems of New Zealand, Ministry for the Environment. Managed by Ministry for the Environment.

Land cover

This database classifies land cover into 35 categories using satellite imagery. The database is used to monitor the natural environment at regional and national scales. Previous versions record past land cover and can be used to track changes over time.

Source and management: Manaaki Whenua - Landcare Research, see New Zealand Land Cover Database, version 5.0.

Natural river and stream cover

This database shows the proportion of native vegetation cover alongside rivers and streams, derived from satellite imagery. Natural cover ranges from 0 to 1, where 1 has the highest proportion of native vegetation.

Source: NIWA, managed by DOC.

Human pressures on rivers and streams

This is an assessment of human pressures on the ecological integrity of rivers and streams along their length. The overall pressure index was calculated from individual pressures:

  • clearance of native vegetation
  • imperviousness
  • stream nitrogen loads
  • mine and industrial discharges
  • upstream and downstream dam effects, and
  • introduction of pest fish.

The index ranges from 0 to 1, where 0 has the most severe pressure.

Source: NIWA, managed by DOC.

Estuary plants and animals

Mangroves

Mangroves are mapped with the most recent data from regional councils, DOC and other agencies.

DOC maintains the New Zealand mangroves and seagrass database, which provides a comprehensive nationwide spatial and temporal habitat layer for this species. Information from other agencies is added as it becomes available.

See New Zealand mangroves and seagrass database.

Seagrass

Seagrass (Zostera muelleri) is mapped with the most recent data from regional councils, DOC and other agencies.

DOC maintains the New Zealand mangroves and seagrass database, which provides a comprehensive nationwide spatial and temporal habitat layer for this species. Information from other agencies is added as it becomes available.

See New Zealand mangroves and seagrass database.

Inanga spawning sites

Records of spawning sites are drawn from iNaturalist as submitted by the public and include historical and recent records. This dataset relies on public observations that are moderated by a subject matter expert, so the data may not be complete or accurate.

Source: iNaturalist inanga spawning sites project. Managed by Shane Orchard.

Email: shane.orchard@canterbury.ac.nz

Estuary classifications and descriptions

Ecological districts

To survey New Zealand’s protected natural areas, 268 ecological districts were identified, based on landscape and ecological features. The districts were further grouped into 85 ecological regions. Ecological regions and districts highlight the similarities of composition, form and function within and between the natural ecosystems inside their boundaries.

Source: Ecological regions and districts of New Zealand (PDF, 506K)

Estuary environment classification

This classification system classifies estuaries into different types based on their climate, catchment characteristics, and ocean and river conditions.

More about estuary types.

Source: NIWA.

Coastal hydrosystem classification

Coastal hydrosystems is a collective term for coastal lakes and wetlands, lagoons, river, estuarine and marine environments. This resource uses a standard set of criteria to classify each hydrosystem based on its physical characteristics.

Classification of New Zealand's coastal hydrosystems.

Source: Ministry for the Environment.

Marine habitats

This dataset maps marine habitats in the New Zealand territorial sea based on surrogates including depth, substratum, exposure and biogenic habitats.

Coastal marine habitats and marine protected areas in the New Zealand Territorial Sea: a broad scale gap analysis.

Managed by DOC.

Wetlands

Current wetland extent (2013)

Wetlands are mapped at 1:50,000 to a minimum size of 0.5 hectares. A combination of satellite imagery and recent survey data was used to map 7 wetland classes:

  • bog
  • fen
  • inland saline
  • marsh
  • pakihi/gumland
  • seepage
  • swamp.

Source: Manaaki Whenua - Landcare Research. Managed by Stats NZ and Ministry for the Environment.

Historical wetland extent

The extent of wetlands before human arrival is mapped at 1:50,000 to a minimum size of 0.5 hectares. The extent is predicted from the national fundamental soil layers (FSL) database, which is used to identify wetland soils from their drainage properties.

Source: Manaaki Whenua - Landcare Research. Managed by Stats NZ and Ministry for the Environment.

Bathymetry and tides

Mean high water springs

Mean high water springs (MHWS) is the averaged highest level that spring tides at full moons reach over many years – often the last 19. It is close to the high water mark where debris accumulates on a tidal shore on about 2 days per year, 6 months apart.

MHWS level is used as the dividing line between land and sea in the Resource Management Act 1991 and the Foreshore and Seabed Act 2004.

Bathymetry (depth)

This dataset is compiled from hydrographic bathymetry datasets sourced from LINZ nautical charts at three scales:

  • 1:22,000–1:90,000
  • 1:90,000–1:350,000, and
  • 1:350,000–1:500,000.

The finest scale, 1:22,000–1:90,000, is used first where it exists. Missing areas are filled with the 1:90,000–1:350,000 then the 1:350,000–1:500,000 datasets.

Some gaps between the coastline and the bathymetry remained, so values from the 1:22,000–1:90,000 polygons were extrapolated into the 1:350,000–1:500,000 polygons where they touched the coastline.

Source: Land Information New Zealand and DOC. Managed by DOC.

Management areas

Public conservation areas

A spatial database of all areas of public conservation land and waters managed by DOC. These include marine mammal sanctuaries, marine reserves and wildlife reserves.

Source and management: DOC.

Type 2 marine protected areas

A spatial database of areas that have restrictions on fishing, mining, aquaculture and dredging to maintain and improve marine biodiversity and protect submarine cables and pipelines. These are managed by the Ministry for Primary Industries, Ministry of Transport and Tāngata Tiaki/Kaitiaki.

Source and management: DOC and Ministry for Primary Industries.

DOC operations regions and districts

DOC has 9 operations regions and 45 operations districts within them. The boundaries were implemented in February 2016 and replaced the previous services regions boundaries.

Source and management: DOC.

Regional councils

Regional council boundaries for 2018 as defined by the regional councils or local government commission. There are 16 regional councils in New Zealand, their seaward boundary is the 12 nautical mile territorial limit.

Source and management: Stats NZ.

Territorial authorities

Territorial authority boundaries for 2018 as defined by the territorial authorities or local government commission. Territorial authorities are the 13 city and 53 district councils. 

Source and management: Stats NZ.

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