Strategic Planning and Resource Managment Team Leader
Waikato District Council
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Waikato District Council - Proposed District Plan (Stage 2 Natural Hazards), Notified 27 July 2020. This layer is a spatial representation of an overlay in the Proposed District Plan and indicates where land use will be regulated by various associated rules. It will be used as a guide in the regulatory process of implementing the Proposed District Plan and managing land use, subdivision, the environment and economy. This dataset is subject to changes undertaken through the Resource Management act. Note individual Proposed Plan rules can have different statuses, some may have current legal effect and others will not until the Proposed Plan becomes operative. This data is provided for use in the District Plan only.
Coastal Sensitivity Area (Open Coast) identifies land in rural areas along the open coastline and within the estuaries, which includes areas of the coastal margin that could potentially be impacted by coastal flooding and/or coastal erosion, assuming sea level rise of 1.0 m to 2120. This belongs to the series of data relating to Natural Hazards which includes the following groups - coastal erosion, coastal inundation, inland flooding, and land subsidence. This layer belongs to both the coastal erosion group and the coastal inundation group. Use in conjunction with High Risk Coastal Hazard (Erosion) Area, Coastal Sensitivity (Erosion) Area, High Risk Coastal Hazard (Inundation) Area, and Coastal Sensitivity (Inundation) 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 hazard area was defined as: a set measurement inland from the shoreline, or calculated using slope analysis (see table 1 of appendix 5(i)) for further details). The general method of the 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. Method was site specific at a lot of locations (see table 1 of appendix 5(i)) for further details). SOURCE DATA: - Elevation data: Waikato - West Coast and Hauraki Plains LiDAR 1 m DEM 2015 (NZTM2000 projection, NZVD2016 vertical datum) - Shoreline data: For areas on the Whaanga coast: the shoreline used was approximated by the 3.5 m contour (NZVD2016) in most locations (4.5m contour at Whale Bay), but adjustments were made at each site to ensure the analysis utilised the toe of cliff. For other areas: the 2012 shoreline data was used as 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). Source of 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. See appendix 5(i) for more detail on which shoreline (or contour) was used at each location. SPATIAL REFERENCE SYSTEM: EPSG2193 SPATIAL REPRESENTATION TYPE: vector ADDITIONAL NOTES: Hazard areas on the Whaanga coast were later reviewed and subsequently superseded by calculation methods outlined in table 1 of appendix 5(i).