Strategic Planning and Resource Managment Team Leader
Waikato District Council
Electronic Mail Address
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.
The Flood Plain Management Area is the floodplain in a 1% Annual Exceedance Probability (AEP) 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 Ponding Area,and Defended Area.
METHODOLOGY: model generated. The Flood Plain Management Area was identified through both 1D and 2D modelling, depending on the level of information available. 2D modelling (generated by DHI) is only available adjacent to the main stem of the Waikato River between Horotiu and Ohinewai and a small length of the Waipa River from Saulbrey Road to the confluence in Ngaruawahia. The 1D modelling extends south from Saulbrey Road to the Waikato district boundary and north from Ohinewai to Port Waikato. An allowance for the projected effects of climate change has been included in the 2D flood modelling (Horotiu to Ohinewai). - 1D modelling methodology: The Waikato Regional Council (WRC) completed 1D flood modelling for the 1% Annual Exceedance Probability (1% AEP) flood event along the full length of the Waikato and Waipa Rivers (within the Waikato District) in November 2016. The model was created by extrapolating the 1959 flood protection scheme design 1% AEP 1D flood model over the adjacent floodplain (topography derived from LiDAR using WaterRide Software) to create a representation of the flood extent. The resulting maps only model flooding from the main river channels (many tributaries and over bank ponding areas are not included) and do not include the projected effects of climate change on rainfall intensity and sea level rise. - 2D modelling methodology: The WRC commissioned DHI to develop a 2D model of the 1% AEP flood event for the Waikato River from Horotiu to Ohinewai and a section of the Waipa River from Saulbrey Road to the confluence at Ngaruawahia. The model was created by....... The data includes allowance for climate change based on 2.3 degreeC scenario. SOURCE DATA: - 2D model: Data provided by Waikato Regional Council (Waikato_Horotiu_to_Ohinewai_2p3deg.shp), generated by DHI - 1D Waipa River model: Original data provided by Waikato Regional Council, amended by Waikato District Council to join lines and transform to polygon format (Waipa_River_1_AEP_2D_extents_placeholderpolygon_createdbyAlex.shp) - 1D Waikato River model: Original data provided by Waikato Regional Council (Waikato_1percent_AEP_2D_flood_extent_final.shp) SPATIAL REFERENCE SYSTEM: EPSG2193 - check this SPATIAL REPRESENTATION TYPE: vector ADDITIONAL NOTES: - Flood Plain Management Area is also present under the High Risk Flood Area. Something to be aware of in case people don't notice these two layers exist on top of each other. - The Flood Plain Management Area does not extend across the middle of the Waikato River channel in the 2D model (from Horotiu to Ohinewai), but it does cover the Waikato and Waipa River channels in the 1D model.