Description: This vector dataset represents a polygonised summary of terrain, hydrological, and regolith susceptibility inputs across DRN watersheds (at 2ha drainage thresholds). It contains zonal statistics derived from continuous raster and classed surfaces, which were used to evaluate spatial variation in erosion susceptibility at sub-catchment scale (DRN 2ha watersheds).Key attributes include majority values from input rasters to S-PAL model (Sediment Process Attribute Layer) such as overland flow or “Sediment runoff risk”, regolith activity or “Geological risk”, hydrological susceptibility or “Soil permeability”, as well as slope and elevation, S-PAL siblings.The symbology (erosion risk classes) of this layer is based on the attribute field “Erosion risk” which is informed by combination of two factors - “Geological risk” and “Sediment runoff risk” at 50:50 ratio.For details see the Land & Water Science report (Gunn and Rissmann 2025) - Northland Erosion and Sediment Risk Map - Metadata Report LWS 2026.pdfAttribute field | Field descriptionsMultiple fields, see below:Erosion Risk: 1-5 categories (where 1 = low risk, and 5 = high risk) from composite of two factors - inherent “Geological risk” and “Sediment runoff risk” at 50:50 ratioGeological RiskA70_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.Sibling_Class_Majority: Majority class from SPAL_4_12_35 rasterAuthor: Dr Clint Rissmann (Land & Water Science)Extent: Whole NorthlandProjection: NZTM (EPSG:2193)Coarsest Scale of Component Dataset: 1:63,000 soil derived informationVersion: Version 2.0Date Created: July 2025Date Modified: May 2026NRC Team (if applicable): Natural Resources Science TeamSubject Matter Expert: Clint Rissmann – Landscape ScientistFile Size: 4.35 GBData Provided by: Manas Chakraborty (Resource Scientist - Freshwater)
Description: This raster represents a continuous composite susceptibility surface based on two SPAL indicators: MADZ-derived regolith activity (i.e. landscape structural instability indicating geological risk) and the OLF (indicating sediment runoff) index. Equal weighting was applied to both inputs:Composite Score = 0.5 × Activity + 0.5 × OLFThe resulting surface was scaled from approximately 1.32 to 4.95 (higher values = higher susceptibility), yielding a continuous measure of erosion susceptibility across the landscape. This supports prioritisation and interpretation at fine spatial resolution.For details see the Land & Water Science report (Gunn and Rissmann 2025) - Northland’s Landscape Driven Erosion Map: A Resource for Decision-Makers and CommunitiesAuthor: Dr Clint Rissmann (Land & Water Science)Extent: Whole NorthlandProjection: NZTM (EPSG:2193)Coarsest Scale of Component Dataset: 1:63,000 resampled to 5mVersion: Version 2.0Date Created: July 2025Date Modified: N/ANRC Team (if applicable): Natural Resources Science TeamSubject Matter Expert: Clint Rissmann – Landscape ScientistFile Size: 1.91 GBRaster Metadata Summary:CRS: NZGD2000 / New Zealand Transverse Mercator (EPSG:2193)Pixel Size: 5 m × 5 mRaster Dimensions: 35,661 (width) × 44,551 (height)Extent: 1567222.5000, 5971572.5000 to 1745527.5000, 6194327.5000GDAL Driver: GTiff (GeoTIFF)Compression: LZWStatistics: Min = 1.3167, Max = 4.9504, Mean = 4.0059, StdDev = 0.1441Valid Data Coverage: 31.27%Data Provided By: Manas Chakraborty (Freshwater Resource Scientist)Data Published By: Bhawana Kafle (Geospatial Analyst)Published Date: 19/02/2026Last Updated By: Jordon Corston (Geospatial Analyst)Last Update Date: 19/05/2026