{ "culture": "en-NZ", "name": "Erosion_and_sediment_risk_map_v2", "guid": "3C5320BE-4C33-42B7-B615-AA362101AFA0", "catalogPath": "", "snippet": "This map of Highly Erodible Land (HEL) is a polygon-based zonal summary of erosion susceptibility indicators for 2 ha Digital River Network (DRN) watershed units across Northland. Includes upstream means and majorities for key terrain, susceptibility, hydrological, and regolith activity metrics.", "description": "

This vector dataset represents a polygonised summary of terrain, hydrological, and regolith susceptibility inputs over 2 ha DRN watersheds. It contains zonal statistics derived from continuous rasters and classed surfaces, used to evaluate spatial variation in erosion susceptibility at the subcatchment scale.Key attributes include majority values from classed S-PAL rasters (e.g. overland flow or OLF quantiles denoted by O, regolith activity quantiles denoted by A, S-PAL sibling classes), as well as upstream means of slope and elevation, and hydrological susceptibility indices (HYD and slope index).<\/span><\/p>

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The symbology (erosion risk classes) of this vector layer is based on composite of two S-PAL factors - regolith activity (A) and overland flow (OLF) susceptibility at 50:50 ratio indicated by the attribute field \u2018A50_O50_Quantile_Majority\u2019.<\/span><\/p>

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For details see the Land & Water Science report (Gunn and Rissmann 2025) - <\/span>Northland's Landscape Driven Erosion Map LWS 2025.pdf<\/span><\/a><\/p>

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Attribute fieldMultiple fields; see below<\/span><\/p>

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Field description<\/span><\/p>

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FID: Internal feature ID<\/span><\/p>

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OBJECTID: Polygon ID same as DRN catchment_2ha ObjectID<\/span><\/p>

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WatershedID: Unique Catchment_2ha watershed ID<\/span><\/p>

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HydroID: Unique ID<\/span><\/p>

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Slope_Mean: Mean slope of watershed (percent)<\/span><\/p>

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Slope_Max: Maximum slope of watershed (percent)<\/span><\/p>

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Elevation_Mean: Mean elevation of watershed<\/span><\/p>

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Elevation_Max: Max elevation of watershed<\/span><\/p>

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Rec2_SegmentID: Unique segment ID from parent REC ver.2 dataset<\/span><\/p>

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Rec2_ReachID: Unique reach ID from parent REC dataset<\/span><\/p>

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Upstream_Slope_Mean: Mean slope of upstream contributing catchment area (percent)<\/span><\/p>

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Upstream_Elevation_Mean: Mean elevation of upstream contributing catchment area<\/span><\/p>

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Upstream_Area: Total upstream contributing catchment area (m²)<\/span><\/p>

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LU_Majority: Majority landuse value across watershed (Land Cover Database ver.5)<\/span><\/p>

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HydroCat: Catchment name<\/span><\/p>

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Shape_Length: Length in metre<\/span><\/p>

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Shape_Area: Area in sq. metre<\/span><\/p>

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OLF_Classes_Majority: Majority class from OLF quantiles (1\u20135), where 1 = low and 5 = high overland flow risk<\/span><\/p>

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Slope_Index_Mean: Mean slope-based index value (continuous). Values range from 0.15 (flat terrain) to 1.0 (very steep terrain).<\/span><\/p>

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HYD_Index_Mean: Mean hydrological susceptibility index (continuous). Values range from 0.0 (low hydrological risk) to 1.0 (high hydrological risk).<\/span><\/p>

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Regolith_Activity_Class_Majority: Majority class from inherent regolith activity quantiles (1 = most active, 5 = least active).<\/span><\/p>

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`A70_O30_Quantile_Majority` to `A30_O70_Quantiles_Majority`: Majority susceptibility class (1-5) from combined susceptibility layers (at various proportions of regolith and OLF susceptibility e.g. 70% regolith and 30% OLF), where 1 = low susceptibility, 2 = moderately low susceptibility, 3 = moderate susceptibility, 4 = moderately high susceptibility, and 5 = high susceptibility.<\/span><\/p>

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Sibling_Class_Majority: Majority class from SPAL_4_12_35 raster<\/span><\/p>

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AuthorDr Clint Rissmann (Land & Water Science)<\/span><\/p>

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ExtentWhole Northland<\/span><\/p>

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ProjectionNZTM (EPSG:2193)<\/span><\/p>

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Coarsest Scale of Component Dataset1:63,000 soil derived information<\/span><\/p>

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VersionVersion 1.0<\/span><\/p>

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Date CreatedJuly 2025<\/span><\/p>

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Date ModifiedN/A<\/span><\/p>

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NRC Team (if applicable)Natural Resources Science Team<\/span><\/p>

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Subject Matter ExpertClint Rissmann \u2013 Landscape Scientist<\/span><\/p>

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File Size4.35 GB<\/span><\/p>

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Vector Metadata SummaryCRS: NZGD2000 / New Zealand Transverse Mercator (EPSG:2193)Geometry: MultiPolygonStorage Format: GPKG (GeoPackage)Extent: 1567223.0000, 5971870.0000 to 1745598.0000, 6194217.0000Feature count: 417,938Encoding: UTF-8<\/span><\/p>

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Data Provided by : Manas Chakraborty (Freshwater Resource Scientist)<\/span><\/p>

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Data Published by: Bhawana Kafle (Geospatial Analyst)<\/span><\/p>

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Data Published date: 19/02/2026<\/span><\/p>

Data Updated as Version 2: 06/03/2026<\/span><\/p><\/div><\/div><\/div>", "summary": "This map of Highly Erodible Land (HEL) is a polygon-based zonal summary of erosion susceptibility indicators for 2 ha Digital River Network (DRN) watershed units across Northland. Includes upstream means and majorities for key terrain, susceptibility, hydrological, and regolith activity metrics.", "title": "Erosion and sediment risk map", "tags": [ "DRN", "susceptibility", "zonal statistics", "erosion", "SPAL", "OLF", "regolith activity", "terrain", "hydrology", "Northland" ], "type": "Map Service", "typeKeywords": [ "ArcGIS", "ArcGIS Server", "Data", "Map Service", "Service" ], "thumbnail": "thumbnail/thumbnail.png", "url": "", "extent": [ [ 172.634465063246, -36.401007150306 ], [ 174.623374814239, -34.3822202146487 ] ], "minScale": 0, "maxScale": 1.7976931348623157E308, "spatialReference": "NZGD_2000_New_Zealand_Transverse_Mercator", "accessInformation": "Land & Water Science, NRC", "licenseInfo": "