Canterbury Wetlands GIS Layer

Description:This geodatabase collates wetland location and extent information for Canterbury Region. Information comes from a variety of sources and has varying levels of detail or precision on features such as wetland location, extent, type, condition and ecological significance.The Canterbury Wetlands geodatabase distinguishes between ‘ground survey-detailed’, ‘ground survey–rapid’ and ‘aerial survey’ wetlands. At present, most of the mapped wetlands are in the ‘aerial survey’ category. Survey methodologies are described below.Initial database coverage of Canterbury Region was completed in March 2019. Updates and edits to the database are ongoing.Background:Canterbury has a wide variety of wetland types, reflecting diverse geography, hydrology and climate. The formal definition of wetlands in the Resource Management Act (1991) is “permanently or intermittently wet areas, shallow water or land/water margins that support a natural ecosystem of plants and animals that are adapted to living in wet conditions”. This definition is very broad and could be interpreted to include all waterbodies – springs, streams, rivers, lakes, estuaries, the marine environment. However, the ‘wetland’ habitats shown in this geodatabase share a number of environmental and ecological features that distinguish them from adjoining aquatic (and terrestrial) ecosystems. These are: Temporary or permanent shallow standing water and/or waterlogged soils; Temporary or permanent anaerobic conditions in the soil; Dominance by emergent aquatic plants.  The Canterbury Wetlands geodatabase generally excludes streams, rivers, lakes and the Coastal Marine Area (CMA) as these waterbodies have been depicted in other datasets, although wetland habitats (as defined above) located on the margins of rivers, streams, lakes and the CMA are included. Nevertheless, wetlands, springs, streams, rivers, lakes, estuaries and the coastal marine environment are all waterbodies which merge into one another and are ecologically connected. We therefore recommend that the Canterbury Wetlands geodatabase is used in conjunction with other spatial information relating to the region’s waterbodies.Methodology:“Ground survey-detailed” wetlands have been field inspected and mapped/described in some detail. These ground surveys have mostly been carried out by Environment Canterbury staff, or wetland ground survey information provided by other agencies such as the Department of Conservation and the New Zealand Defence Force. Wetlands that have been ecologically surveyed and mapped as part of Resource Consent Applications may also be included in this category.For vegetated wetland survey areas, wetland boundaries are delineated where more than 50% of the dominant plant species from all vegetation strata are ‘Obligate’, ‘Facultative Wetland’ or ‘Facultative’ (i.e. the plant community is considered hydrophytic – Clarkson 2013). Descriptions of wetland hydrosystems, wetland class and vegetation types listed in the attributes tables for ground surveyed wetlands follow Johnson and Gerbeaux (2004), while assessment scores for wetland condition and threat follow Clarkson et al. (2003 & 2014).  An assessment of ecological significance against Canterbury Regional Policy Statement criteria is also provided for “ground survey-detailed” wetlands.“Ground survey-rapid” wetlands have also been field inspected with the presence and extent of wetland habitats confirmed. Again, wetland boundaries are delineated where more than 50% of the dominant plant species from all vegetation strata are ‘Obligate’, ‘Facultative Wetland’ or ‘Facultative’ (Clarkson 2013).“Aerial survey” wetlands have been mapped by delineating the outline of known and likely/potential wetland habitats from the latest high-resolution aerial imagery available at the time of mapping. Characteristic vegetation types, colours, patterns, presence of visible water were used to identify wetlands on aerial photos, with hydrological and topographical information also considered. Note that precision limitations and uncertainties mean that there will be errors or omissions in this part of the dataset. We also did not attempt to map wetland habitats smaller than 50m and/or narrower than 5m by the ‘aerial survey’ method. For this reason, ‘aerial survey’ wetlands in this geodatabase should be used to indicate likely presence of wetlands but should not relied on to show precise extent of wetlands depicted, or location of all wetland habitats.Where available, existing ecological information for ‘aerial survey’ wetlands is noted in the attributes and the source referenced. However, for most ‘aerial survey’ wetlands, apart from date of base imagery and data capture, no further information is provided in the attributes.Currency:Current at time of survey date for ‘ground survey – detailed’ and ‘ground survey – rapid’ sites; current to date of aerial imagery for ‘aerial survey’ sites.Data owner:Environment CanterburyData interpretation and limitations:The Canterbury Wetlands geodatabase is not a ‘schedule’ in a plan and has not been tested through a statutory planning process. The GIS layer is not comprehensive, nor does it attempt to systematically apply the Canterbury Land and Water Regional Plan definition of ‘wetland’. Nor does it attempt to apply the definition of ‘natural wetland’ in the National Policy Statement-Freshwater Management (NPS-FM) or National Environmental Standards-Freshwater (NES-F). The database is not ‘locked in’ and can potentially be changed or updated with more information. Attributes of the Canterbury Wetlands geodatabaseNote: the attribute tables will only be complete for ‘ground surveyed – detailed’ wetlands.AREA NAMEName of wetland or survey area.HYDROSYSTEMWetland ecosystems are differentiated by landform and hydrological setting, and by water salinity, chemistry and temperature. Estuarine, riverine, lacustrine and palustrine hydrosystems have been recorded for ground-surveyed wetlands in Canterbury.SUBSYSTEMHydrosystems can be further described according to the water regime. Periodicity of inundation is the main feature e.g. permanent, seasonal, tidal, non-tidal, ephemeral.WETLAND CLASSMain wetland classes for Canterbury are swamp, marsh, fen, bog, seepage, shallow water, ephemeral wetland and saltmarsh.WETLAND FORMLandforms that wetlands occupy, and forms they create or contain.VEGETATION TYPEDominant vegetation type(s) within wetland. A general description of the growth form (or structure) and composition of the vegetation. For example: raupō reedland, saltmarsh herbfield, willow forest.SURVEY TYPE‘Ground survey-detailed’, ‘Ground survey-rapid’ or ‘Aerial survey’.SURVEY DATEDate of wetland ground survey or delineation by aerial survey.IMAGERY DATEDate of imagery used when delineating wetlands by aerial survey method.ECOLOGICAL SIGNIFICANCEAssessment of ecological significance for ground surveyed wetlands against Canterbury Regional Policy Statement (CRPS) criteria and associated guidelines (Wildland Consultants, 2013). Three level score:High: Meets one or more significance criteria; Regionally, Nationally or Internationally SignificantModerate: Meets one or more significance criteria; Locally SignificantLow: Does not meet any CRPS ecological significance criteriaWetland IDUnique wetland polygon identification numberDocument ID 1Hyperlink to wetland condition, threat and significance assessment (only for ‘ground survey – detailed’ wetlands).Document ID 2Hyperlink to historic wetland condition, threat and significance assessment (only for repeat ground survey-detailed wetlands). ReferencesClarkson BR, Sorrell BK, Reeves PN, Champion PD, Partridge TR, Clarkson BD. 2003. Handbook for monitoring wetland condition. Coordinated monitoring of New Zealand wetlands. A Ministry for the Environment SMF funded project. Ministry for the Environment, Wellington. 74pp.Clarkson BR. 2013. A vegetation tool for wetland delineation in New Zealand. Landcare Research contract report prepared for Meridian Energy Limited. 62pp.Clarkson BR, Fitzgerald NB, Overton JM 2014. A methodology for monitoring Bay of Plenty wetlands. Landcare Research contract report LC1779.Fraser S, Singleton P, Clarkson BR. 2018. Hydric soils – field identification guide. Landcare Research contract report LC3233.Johnson P. Gerbeaux G. 2004. Wetland Types in New Zealand. Department of Conservation. Wellington. 184pp.Wildlands Consultants. 2013. Guidelines for the application of ecological significance criteria for indigenous vegetation and habitats of indigenous fauna in Canterbury Region. Contract Report No. 2289i.

This geodatabase can be found internally as GIS.DBO.WETLANDS_NZTM_Canterbury_Wetlands_Updated2019

Data and Resources

Additional Info

Field Value
Theme ["geospatial"]
Author Canterbury Regional Council
Maintainer canterburymaps
Maintainer Email canterburymaps
Created 2019-04-23T04:29:55.000Z
Date modified 2021-04-22T22:50:33.000Z
Language English
Spatial {"type": "Polygon", "coordinates": [[[169.5167, -45.0332], [174.0602, -45.0332], [174.0602, -41.9338], [169.5167, -41.9338], [169.5167, -45.0332]]]}
Source Identifier
Record created March 8, 2021, Last Updated May 2, 2021