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.
Defended Areas are areas of land that would be at risk from flooding during a 1% Annual Exceedance Probability (AEP) flood event if it were not for a structural defence such as a stopbank (These areas are not defended from all flood events. They are defended from flooding from a specified water course up to a specified design flood event). 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 the inland flooding group. Use in conjunction with High Risk Flood Area, Flood Plain Management Area,and Flood Ponding Area.
METHODOLOGY: Defended Areas were determined using the following process: For all stopbanks or defended areas outside of the Huntly Urban area, the defended area was defined using existing WRC Direct Benefit Rating layers (GIS_ALL.RACS_RATE_WAIKWAIP_DIR_BENEFIT; under “RACS – Rating Scheme – Waikato-Waipa – GIS Layer” in the WRC Data Catalogue), and included an expert review to ensure correct benefit areas were used. (Note: only areas protected from flooding during a 1% Annual Exceedance Probability (AEP) flood event, by a flood protection scheme managed by the WRC, the Council (WDC) or the Crown are included in this Defended Areas layer). For all stopbanks or defended areas within the Huntly Urban area, the defended area is defined as ground areas (based on 2007/2008 LiDAR) at or below the Design Flood Level of the relevant stopbank reach. SOURCE DATA: Shapefile was provided by Waikato Regional Council on 17 March 2020, via email (archived in ECM 2742394). The shapefile provided included the final data used in the Notified version of the Proposed District Plan. However, not the entire dataset was used in the Notified version of the Proposed District Plan - Only the 1% AEP areas from this file were used as the final shape in the Notified version of the Proposed District Plan. The shapefile provided was cleansed because it was giving geometry errors (such as ring self-intersections, and nested shells). A combination of cleansing methods were used including ‘fix geometries’ in QGIS, and a 10cm negative buffer which fixed shared intersecting corner nodes. SPATIAL REFERENCE SYSTEM: EPSG2193 SPATIAL REPRESENTATION TYPE: vector DATA OWNER: Waikato Regional Council