Proposed High Risk Coastal Hazard (Erosion) Area

METHODOLOGY: hand digitised.
Method of assessment included field observations and desktop study. The coastal environment was split into and assessed in broad management areas. The extent of the hazard area was defined as either: a set measurement inland from a shoreline, or a defined area (such as coastal spit), or calculated using slope analysis (see appendix A of appendix 5(h) and table 1 of appendix 5(i)) for further details).
The general method for slope analysis was to take transects along the coast to collect points to represent the width of hazard area. A point on each transect was calculated by taking a measure from toe of slope (defined using DEM) inland a set distance to account for toe erosion (if applicable), then a defined slope angle was applied and the point where this intersected the land surface was recorded as width of hazard area on that transect. Points between transects were joined with straight lines.
SOURCE DATA:
- Elevation data: Contour data sourced from any of the following: Waikato - West Coast and Hauraki Plains LiDAR 1 m DEM 2015 (NZTM2000 projection, NZVD2016 vertical datum), EW - North Waikato 2010 DEM BC31_0711 (NZTM projection, MVD1953), NZAM LiDAR Raglan 2009 DEM (NZTM projection, MVD1953), EW Original data Raglan Harbor 2010 DEM BD32_1405, BD32_1305, BD32_1304 (NZTM projection, MVD1953).
- Shoreline data: Shoreline data was provided by provided by 4D Environmental Ltd on 21/08/2019 via email as a shapefile (NZTM2000 projection). The shapefile has been archived in ECM (document ID 2327334). The Shoreline provided was the 2012 shoreline, and a small portion of 2017 and 2019 shorelines were also provided (the source of the 2012 shoreline was taken from 2012 WRAPS, which was prepared for WRC for use at 1:8,000 scale. In reality most of it was mapped at about 1:5,000.). A specific shoreline for Lorenzen Bay was also provided by 4D Environmental Ltd on 5/09/2019 via email as a shapefile (NZTM2000 projection) (archived in ECM (Document Set ID 2376525)). Appendix A of appendix 5(h) shows which shoreline (or contour) was used at each location.
- Management Areas (referred to in appendix A of appendix 5(h)): The coastal environment was split into management areas for assessment of natural hazards. 4D Environmental Ltd provided a shapefile to show the extent of the areas (NZTM2000 projection) (this has been archived in ECM as Document Set ID 2376504).
SPATIAL REFERENCE SYSTEM: EPSG2193
SPATIAL REPRESENTATION TYPE: vector