Areas adjacent to the 100yr ARI floodplain that are within 0.5m of the predicted 100yr ARI flood level. These mapped areas are to ensure the appropriate planning rules are considered for properties developing adjacent to the floodplain Created by the Stormwater Hydraulic Modelling Team Last Update 23 May 2013Disclaimer: In using the Catchments and Hydrology data set, you acknowledge that you have read, understood and agreed to the disclaimers below.The flood plains and flood sensitive area data layers are generated from catchment level modelling based on the datasets, requirements and technology available at the time of model build. They are compiled regional layers with varied data uncertainty and currency, which may directly impact data accuracy for the area of interest. The information provided therefore does not preclude the need for appropriate site-specific assessment and cannot be construed as an endorsement or approval of any development by Auckland Council.The Catchments and Hydrology data set is updated regularly when new information becomes available. As such, downloading and copying activities may result in data invalidity.Whilst due care has been taken in producing the Catchments and Hydrology data sets, Auckland Council gives no warranty as to the accuracy and completeness of any information given and accepts no liability for any error, omission or use of the information.

Purpose:The coastal inundation hazard layers map describes the areas exposed to extreme water levels caused by storm tides, wave setup and sea-level rise under the following scenarios (where AEP is the Annual Exceedance Probability or the chance of occurring each year, ARI is the Average Recurrence Interval):20% AEP (5 year return)5% AEP (20 year return)2% AEP (50 year return)1% AEP (100 year return): to demonstrate present day risk in alignment with the Auckland Unitary Plan activity controls2% AEP (50 year return) + 1m sea level rise2% AEP (50 year return) + 2m sea level rise1% AEP (100 year return) + 1m sea level rise: in alignment with Auckland Unitary Plan activity controls1% AEP (100 year return) + 2m sea level rise: to demonstrate longer term risk with ongoing sea-level riseThis is a generalised version of the data. Download the original full dataset with layer files here:https://data-aucklandcouncil.opendata.arcgis.com/datasets/coastal-inundation-hazards-geodatabase/aboutThe layer takes into account extreme sea levels calculated between 2013 and 2019, as compiled in Carpenter, N., R Roberts and P Klinac (2020). Auckland’s exposure to coastal inundation by storm-tides and waves. Auckland Council technical report, TR2020/24. Auckland’s exposure to coastal inundation by storm-tides and waves (knowledgeauckland.org.nz)Sea-level rise values applied currently align with the projections by the Intergovernmental Panel on Climate Change sixth assessment report (2021), and the Ministry for the Environment (2022) Interim guidance on the use of new sea-level rise projections, which updates the Ministry for the Environment Coastal Hazards and Climate Change Guidance for Local Government (2017). In MfE’s (2022) Interim guidance, (excluding vertical land movement) one metre sea-level rise is projected to occur between 2095 - >2200, depending on the emission scenario used. Two metre sea-level rise is projected to occur in the longer term (beyond 2150). MfE’s (2022) Interim guidance recommends the inclusion of vertical land movement (VLM) in relative sea level rise considerations. These are not included in the above sea level rise predictions due to the high VLM variability across the region. Vertical land movement is generally predicted to increase the rates of relative sea level rise for the Auckland region so should also be incorporated in planning and design.Refer to Interim guidance on the use of new sea-level rise projections | Ministry for the Environment for more information on MfE’s interim guidance on sea level rise and vertical land movement.Lineage:3Extreme sea levels for the Auckland region were derived by NIWA in 2013 (Part 1 of Technical Report 2020/24). From 2016-2019, additional extreme sea level data was gathered for:The east coast estuaries (NIWA, 2016; Part 2 of Technical Report 2020/24)Parakai/Helensville Harbour (DHI, 2019; Part 3 of Technical Report 2020/24)Great Barrier Island (NIWA, 2019; Part 4 of Technical Report 2020/24)In 2020, these levels were projected onto the land topography (derived from the 2016-2018 LiDAR survey) by Stantec to establish the extent of coastal flooding. Creation Date: 15/12/2020Update Cycle: Adhoc – when improved data becomes availableThis data is available to the public on the Geomaps viewer and is copied into LIMsContact Person: Natasha CarpenterContact Position:Coastal Management Practice Lead, Infrastructure and Environmental ServicesCouncil Contact:Natasha.Carpenter@aucklandcouncil.govt.nzConstraints – General:The Coastal Inundation data is subject to updates to reflect the latest, best available understanding of storm tides, waves and sea-level rise processes.The geodatabase contains a copy of the historic inundation mapping, which is superseded by the publication of the 2020 data. The superseded data is identified by having a validation state of 0, whereas the published data has a validation state of 3 (valid and public).Constraints – Legal: This data is available to the public on the Geomaps viewer and is copied into LIMsConstraints – Security: The Coastal Inundation data is available to the public Under Creative Commons license.

The flood plains indicate the area of land inundated by runoff in a storm event that has a 1 percent or greater probability of occurring in any given year, assuming maximum probable development (MPD) and future climate change. The flood plains are mapped from hydraulic modelling results. Information specific to each flood plain is accessible using the Identify tool, including the flood report. This dataset is continually updated at catchment scale to reflect the best information available.This dataset is updated by the Heathy Waters team on a regular basis.Disclaimer: In using the Catchments and Hydrology data set, you acknowledge that you have read, understood and agreed to the disclaimers below.The flood plains and flood sensitive area data layers are generated from catchment level modelling based on the datasets, requirements and technology available at the time of model build. They are compiled regional layers with varied data uncertainty and currency, which may directly impact data accuracy for the area of interest. The information provided therefore does not preclude the need for appropriate site-specific assessment and cannot be construed as an endorsement or approval of any development by Auckland Council.The Catchments and Hydrology data set is updated regularly when new information becomes available. As such, downloading and copying activities may result in data invalidity.Whilst due care has been taken in producing the Catchments and Hydrology data sets, Auckland Council gives no warranty as to the accuracy and completeness of any information given and accepts no liability for any error, omission or use of the information.

Flood Risk Areas are shown on the planning maps but also apply to any other land that is subject to more than minor flood hazards. Waikato Regional Council information.

The Waikato District Council District Plan is has been produced under the Resource Management Act 1991, and has been distributed to allow better public access to the data underlying the Plan. While you are free to crop, export and repurpose the data, we ask that you attribute the Waikato District Council, link to this page, and clearly state that your work is a derivative and not the authoritative data source. Please include this statement when distributing any work derived from this data:

This work is a derivative of Policy Series, part of the Waikato District Council District Plan. You can find the full District Plan at Waikato District E-Plan (https://www.waikatodistrict.govt.nz/your-council/plans-policies-and-bylaws/plans/district-plan)

This layer provides polygons of approximate flood areas derived from Sentinel-1 satellite radar imagery captured at various times on 14/02/2023 near the peak of the Cyclone Gabrielle event in the North Island of New Zealand. Areas of coverage for this layer include the Hauraki, Thames-Coromandel and Hastings Districts, and Napier City.

​(Note: More accurate and validated flood extent models for the Hawke’s Bay region can be obtained from Hawke’s Bay Regional Council - Flood Observation Extents.)

​This dataset was created by Toitū Te Whenua LINZ as part of its contribution to the emergency response, and is limited to areas that had a satellite pass over, and to the few areas of interest as we knew them at the time.

​**Accuracy** Users of this data should exercise caution . The accuracy of this data has not been validated. A subjective threshold was used to determine possible flood areas and eliminate false positives. Polygons in hilly areas or below a certain area size were excluded as likely false positives.

Please use this data as advisory only. The results have not been ground truthed and will contain errors and ommissions.

Made available for NPDC GeoHUB (GIS Hub Site and Open Data Portal) :A full description is available in the Metadata. SeeTerms of Use.Notes:The "Updated" date, noted here in the item, does not accurately reflect the currency of the data within the Feature Layer.The data available for download on NPDC GeoHUB is updated daily, this results in differences between what is available online and NPDC's databases.

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.

Flood Ponding Areas are areas of land that experience floodwater ponding in a 1% Annual Exceedance Probability (AEP) rainfall event. Only two Flood Ponding Areas have been specifically identified on the planning maps. One of the areas is located in the southern part of Huntly adjacent to the eastern bank of the Waikato River and the other is in Huntly West adjacent to Lake Waahi and Lake Puketirini. 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 Defended Area.

The Coastal Storm Inundation dataset maps the extent of sea water coverage expected around the Auckland Region during sustained coastal storm-tide flooding events. Elevated storm-tide sea levels are predicted based on the joint probability of a high tide, a storm surge (which is the rise in sea-level caused by wind action and low barometric pressure related to storm events), and wave setup. (Wave setup is the elevation of the mean sea level at the shoreline due to breaking waves. Larger dynamic wave processes like wave runup and overtopping are not included in this mapping so should be considered on top of these water levels. Rainfall and freshwater flooding are also not included in this data, but are available separately in other geomaps layers e.g. ‘Flood Plains’, or on the Auckland Flood Viewer). Coastal inundation (or coastal flooding) is mapped for a range of Annual Exceedance Probability (AEP) events, where the AEP is the % probability of an event occurring each year. Extreme events can also often be referred to by their return period, or Average Recurrence Interval (ARI). The table below gives the conversion between the two terminologies:AEP (%)ARI (yr)18.154.9202.0501.0100The extreme sea level events were calculated between 2013 and 2019, as compiled in Carpenter, N., R Roberts and P Klinac (2020), Auckland’s exposure to coastal inundation by storm-tides and waves, Auckland Council technical report, TR2020/24, Auckland’s exposure to coastal inundation by storm-tides and waves (knowledgeauckland.org.nz)Increments of sea level rise have been applied on top of storm-tide sea level events in order to assess the increasing coastal flooding hazard into the future. Sea-level rise values applied currently align with the projections by the Intergovernmental Panel on Climate Change sixth assessment report (2021), and the Ministry for the Environment (2022) Interim guidance on the use of new sea-level rise projections, which updates the Ministry for the Environment Coastal Hazards and Climate Change Guidance for Local Government (2017). In MfE’s (2022) interim guidance, (excluding vertical land movement) one metre sea-level rise is projected to occur between 2095 - >2200, depending on the emission scenario used. Two metre sea-level rise is projected to occur in the longer term (beyond 2150).MfE’s (2022) Interim guidance recommends the inclusion of vertical land movement (VLM) in relative sea level rise considerations. These are not included in the above sea level rise predictions due to the high VLM variability across the region. Vertical land movement is generally predicted to increase the rates of relative sea level rise for the Auckland region so should also be incorporated in planning and design.Refer to Interim guidance on the use of new sea-level rise projections | Ministry for the Environmentand NZ Sea Risefor more information on MfE’s interim guidance on sea level rise and vertical land movement.The inundation mapping is based on the Digital Elevation Model ground levels surveyed by aerial LiDAR between 2016-2018. Coastal inundation mapping is not available for some scenarios for the Parakai-Helensville area as this area’s complex dynamics requires hydrodynamic modelling to accurately assess the coastal storm inundation extent. Hydrodynamic modelling has not yet been carried out for all scenarios (e.g. 1.5m sea level rise) but is available for most 2% & 1% AEP scenarios and all tidal (MHWS) scenarios. Please see technical report 2020/024for information on the hydrodynamic modelling. Extreme sea levels for the Auckland region were derived by NIWA in 2013 (Part 1 of Technical Report 2020/24). From 2016-2019, additional extreme sea level data was gathered for:The east coast estuaries (NIWA, 2016; Part 2 of Technical Report 2020/24)Parakai/Helensville Harbour (DHI, 2019; Part 3 of Technical Report 2020/24)Great Barrier Island (NIWA, 2019; Part 4 of Technical Report 2020/24)In 2020, these levels were projected onto the land topography (derived from the 2016-2018 LiDAR survey) by Stantec to establish the extent of coastal flooding. Additional coastal flooding scenarios (annual exceedance probability events + sea level rise) were mapped in 2023 by Watershed Engineering and mean high water spring tides + sea level rise were mapped by NIWA.(Note: The studies informing this mapping of coastal inundation generally used Auckland Vertical Datum 1946. Auckland Council is now transitioning to using New Zealand Vertical Datum 2016.)Update Cycle:Adhoc when improved data becomes available.This data is available to the public on the Geomaps viewer and on Auckland Council Open Data portaland some coastal flood mapping is copied into LIM reports.

This layer contains the index tiles for LiDAR data for the Nelson - Tasman region, captured between 23 August 2022 and 6 September 2022.

• The DEM is available as layer Nelson and Tasman - Top of the South Flood LiDAR 1m DEM (2022).

• The DSM is available as layer Nelson and Tasman - Top of the South Flood LiDAR 1m DSM (2022.

• The LAS point cloud and vendor project reports are available from OpenTopography.

LiDAR was captured for Nelson City Council, Tasman District Council, Waka Kotahi NZ Transport Agency and the National Emergency Management Agency by Aerial Surveys Ltd between 23 August 2022 and 6 September 2022. These datasets were generated by Arial Surveys Ltd and their subcontractors. Data management and distribution is by Toitū Te Whenua Land Information New Zealand. Coverage includes Nelson to Brightwater, including the Waimea River, State Highway 6 from Hira to Rai Valley and Ōkiwi Bay access road, plus Abel Tasman Drive, Bird Hill and Takaka Hill in Golden Bay.

Data comprises:

• DEM: tif or asc tiles in NZTM2000 projection, tiled into a 1:1,000 tile layout

• DSM: tif or asc tiles in NZTM2000 projection, tiled into a 1:1,000 tile layout

• Point cloud: las tiles in NZTM2000 projection, tiled into a 1:1,000 tile layout

Pulse density specification is at a minimum of 2.8 pulses/square metre.

Vertical Accuracy Specification is +/- 0.2m (95%) Horizontal Accuracy Specification is +/- 1.0m (95%)

Vertical datum is NZVD2016.

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.

High Flood Risk Areas are identified as areas within the Flood Plain Management Area where the depth of flood water in a 1% Annual Exceedance Probability (AEP) flood event exceeds 1 metre and the speed of flood water exceeds 2 metres per second. 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 Flood Plain Management Area, Flood Ponding Area,and Defended Area.

An interactive viewer of the Bay of Plenty's natural hazards. Explore this map to discover information on the natural hazards that impact our region. Rebuilt in 2023.

A record of the Top of the South Island severe weather emergency event August 2022.

Orthophotography within the Tasman, Nelson City and Marlborough District totaling approximately 918km². Captured between the 23rd August 2022 and 6th September 2022. Coverage includes Nelson to Brightwater, including the Waimea River, State Highway 6 from Hira to Rai Valley and Ōkiwi Bay access road, plus Abel Tasman Drive, Bird Hill and Takaka Hill in Golden Bay.

Imagery was captured for Nelson City Council, Tasman District Council and Waka Kotahi by Aerial Surveys Ltd, Unit A1, 8 Saturn Place, Albany 0632, New Zealand.

Data comprises: • 2658 ortho-rectified RGB GeoTIFF images in NZTM projection, tiled into the LINZ Standard 1:1000 tile layout • Tile layout in NZTM projection containing relevant information.

The supplied imagery is in terms of New Zealand Transverse Mercator (NZTM) map projection. Please refer to the tile index layer for specific details, naming conventions, etc.

Imagery supplied as 15cm pixel resolution (0.15 m GSD), 3-band (RGB) uncompressed GeoTIFF. The final spatial accuracy is ±0.5 at 95% confidence level in clear flat areas.

Index tiles for this dataset are available as layer Top of the South 0.15m Flood Aerial Photos Index Tiles (2022)

This line shows the limit of flooding from the Whangamarino Wetland and Lake Waikare in Te Kauwhata. This is a site specific layer derived from the Te Kauwhata storm water catchment management plan prepared be Beca Infrastructure Ltd (July 2009). This is a dataset derived from hydrological model. The inputs variables and assumptions for the model are not know. These data are not scheduled for review.

The Waikato District Council District Plan is has been produced under the Resource Management Act 1991, and has been distributed to allow better public access to the data underlying the Plan. While you are free to crop, export and repurpose the data, we ask that you attribute the Waikato District Council, link to this page, and clearly state that your work is a derivative and not the authoritative data source. Please include this statement when distributing any work derived from this data:

This work is a derivative of Policy Series, part of the Waikato District Council District Plan. You can find the full District Plan at Waikato District E-Plan (https://www.waikatodistrict.govt.nz/your-council/plans-policies-and-bylaws/plans/district-plan)

Torrential rain hit the Bay of Plenty, specifically the Rangitaiki, Whakatane and Waimana Catchments from 15 July to 18 July 2004 when a trough of low pressure stalled directly over the Rangitaiki Plains. Extensive flooding from river and surface ponding resulted. A stopbank breach on the East bank above the town of Edgecumbe exacerbated the situation. Part of Whakatane town also flooded due to the heavy rain. A civil defence emergency resulted, with about 1000 evacuees, huge stock movements and major loss of propertyIt is envisaged that any mapping of future flood event extents would be added to this dataset.

The Coastal Storm Inundation dataset maps the extent of sea water coverage expected around the Auckland Region during sustained coastal storm-tide flooding events. Elevated storm-tide sea levels are predicted based on the joint probability of a high tide, a storm surge (which is the rise in sea-level caused by wind action and low barometric pressure related to storm events), and wave setup. (Wave setup is the elevation of the mean sea level at the shoreline due to breaking waves. Larger dynamic wave processes like wave runup and overtopping are not included in this mapping so should be considered on top of these water levels. Rainfall and freshwater flooding are also not included in this data, but are available separately in other geomaps layers e.g. ‘Flood Plains’, or on the Auckland Flood Viewer). Coastal inundation (or coastal flooding) is mapped for a range of Annual Exceedance Probability (AEP) events, where the AEP is the % probability of an event occurring each year. Extreme events can also often be referred to by their return period, or Average Recurrence Interval (ARI). The table below gives the conversion between the two terminologies:AEP (%)ARI (yr)18.154.9202.0501.0100The extreme sea level events were calculated between 2013 and 2019, as compiled in Carpenter, N., R Roberts and P Klinac (2020), Auckland’s exposure to coastal inundation by storm-tides and waves, Auckland Council technical report, TR2020/24, Auckland’s exposure to coastal inundation by storm-tides and waves (knowledgeauckland.org.nz)Increments of sea level rise have been applied on top of storm-tide sea level events in order to assess the increasing coastal flooding hazard into the future. Sea-level rise values applied currently align with the projections by the Intergovernmental Panel on Climate Change sixth assessment report (2021), and the Ministry for the Environment (2022) Interim guidance on the use of new sea-level rise projections, which updates the Ministry for the Environment Coastal Hazards and Climate Change Guidance for Local Government (2017). In MfE’s (2022) interim guidance, (excluding vertical land movement) one metre sea-level rise is projected to occur between 2095 - >2200, depending on the emission scenario used. Two metre sea-level rise is projected to occur in the longer term (beyond 2150).MfE’s (2022) Interim guidance recommends the inclusion of vertical land movement (VLM) in relative sea level rise considerations. These are not included in the above sea level rise predictions due to the high VLM variability across the region. Vertical land movement is generally predicted to increase the rates of relative sea level rise for the Auckland region so should also be incorporated in planning and design.Refer to Interim guidance on the use of new sea-level rise projections | Ministry for the Environmentand NZ Sea Risefor more information on MfE’s interim guidance on sea level rise and vertical land movement.The inundation mapping is based on the Digital Elevation Model ground levels surveyed by aerial LiDAR between 2016-2018. Coastal inundation mapping is not available for some scenarios for the Parakai-Helensville area as this area’s complex dynamics requires hydrodynamic modelling to accurately assess the coastal storm inundation extent. Hydrodynamic modelling has not yet been carried out for all scenarios (e.g. 1.5m sea level rise) but is available for most 2% & 1% AEP scenarios and all tidal (MHWS) scenarios. Please see technical report 2020/024for information on the hydrodynamic modelling. Extreme sea levels for the Auckland region were derived by NIWA in 2013 (Part 1 of Technical Report 2020/24). From 2016-2019, additional extreme sea level data was gathered for:The east coast estuaries (NIWA, 2016; Part 2 of Technical Report 2020/24)Parakai/Helensville Harbour (DHI, 2019; Part 3 of Technical Report 2020/24)Great Barrier Island (NIWA, 2019; Part 4 of Technical Report 2020/24)In 2020, these levels were projected onto the land topography (derived from the 2016-2018 LiDAR survey) by Stantec to establish the extent of coastal flooding. Additional coastal flooding scenarios (annual exceedance probability events + sea level rise) were mapped in 2023 by Watershed Engineering and mean high water spring tides + sea level rise were mapped by NIWA.(Note: The studies informing this mapping of coastal inundation generally used Auckland Vertical Datum 1946. Auckland Council is now transitioning to using New Zealand Vertical Datum 2016.)Update Cycle:Adhoc when improved data becomes available.This data is available to the public on the Geomaps viewer and on Auckland Council Open Data portaland some coastal flood mapping is copied into LIM reports.

The Coastal Storm Inundation dataset maps the extent of sea water coverage expected around the Auckland Region during sustained coastal storm-tide flooding events. Elevated storm-tide sea levels are predicted based on the joint probability of a high tide, a storm surge (which is the rise in sea-level caused by wind action and low barometric pressure related to storm events), and wave setup. (Wave setup is the elevation of the mean sea level at the shoreline due to breaking waves. Larger dynamic wave processes like wave runup and overtopping are not included in this mapping so should be considered on top of these water levels. Rainfall and freshwater flooding are also not included in this data, but are available separately in other geomaps layers e.g. ‘Flood Plains’, or on the Auckland Flood Viewer). Coastal inundation (or coastal flooding) is mapped for a range of Annual Exceedance Probability (AEP) events, where the AEP is the % probability of an event occurring each year. Extreme events can also often be referred to by their return period, or Average Recurrence Interval (ARI). The table below gives the conversion between the two terminologies:AEP (%)ARI (yr)18.154.9202.0501.0100The extreme sea level events were calculated between 2013 and 2019, as compiled in Carpenter, N., R Roberts and P Klinac (2020), Auckland’s exposure to coastal inundation by storm-tides and waves, Auckland Council technical report, TR2020/24, Auckland’s exposure to coastal inundation by storm-tides and waves (knowledgeauckland.org.nz)Increments of sea level rise have been applied on top of storm-tide sea level events in order to assess the increasing coastal flooding hazard into the future. Sea-level rise values applied currently align with the projections by the Intergovernmental Panel on Climate Change sixth assessment report (2021), and the Ministry for the Environment (2022) Interim guidance on the use of new sea-level rise projections, which updates the Ministry for the Environment Coastal Hazards and Climate Change Guidance for Local Government (2017). In MfE’s (2022) interim guidance, (excluding vertical land movement) one metre sea-level rise is projected to occur between 2095 - >2200, depending on the emission scenario used. Two metre sea-level rise is projected to occur in the longer term (beyond 2150).MfE’s (2022) Interim guidance recommends the inclusion of vertical land movement (VLM) in relative sea level rise considerations. These are not included in the above sea level rise predictions due to the high VLM variability across the region. Vertical land movement is generally predicted to increase the rates of relative sea level rise for the Auckland region so should also be incorporated in planning and design.Refer to Interim guidance on the use of new sea-level rise projections | Ministry for the Environmentand NZ Sea Risefor more information on MfE’s interim guidance on sea level rise and vertical land movement.The inundation mapping is based on the Digital Elevation Model ground levels surveyed by aerial LiDAR between 2016-2018. Coastal inundation mapping is not available for some scenarios for the Parakai-Helensville area as this area’s complex dynamics requires hydrodynamic modelling to accurately assess the coastal storm inundation extent. Hydrodynamic modelling has not yet been carried out for all scenarios (e.g. 1.5m sea level rise) but is available for most 2% & 1% AEP scenarios and all tidal (MHWS) scenarios. Please see technical report 2020/024for information on the hydrodynamic modelling. Extreme sea levels for the Auckland region were derived by NIWA in 2013 (Part 1 of Technical Report 2020/24). From 2016-2019, additional extreme sea level data was gathered for:The east coast estuaries (NIWA, 2016; Part 2 of Technical Report 2020/24)Parakai/Helensville Harbour (DHI, 2019; Part 3 of Technical Report 2020/24)Great Barrier Island (NIWA, 2019; Part 4 of Technical Report 2020/24)In 2020, these levels were projected onto the land topography (derived from the 2016-2018 LiDAR survey) by Stantec to establish the extent of coastal flooding. Additional coastal flooding scenarios (annual exceedance probability events + sea level rise) were mapped in 2023 by Watershed Engineering and mean high water spring tides + sea level rise were mapped by NIWA.(Note: The studies informing this mapping of coastal inundation generally used Auckland Vertical Datum 1946. Auckland Council is now transitioning to using New Zealand Vertical Datum 2016.)Update Cycle:Adhoc when improved data becomes available.This data is available to the public on the Geomaps viewer and on Auckland Council Open Data portaland some coastal flood mapping is copied into LIM reports.

The Tidal Inundation & Sea Level Rise dataset maps the extent of sea water coverage expected around the Auckland Region in the future with sea level rise during high tides alone. These water levels are based on The Mean High Water Spring Tide Sea Levels + 0.5m increments of sea level rise. The Mean High Water Spring Tide Sea Levels are the elevation of the high tide that is equalled or exceeded by only the highest 10% of all high tides.These high tide levels include the astronomically driven tide only (due to rotational and gravitational effects) and do not include waves or storm surges (which are the rise in sea level caused by wind action and low barometric pressure related to storm events). The extent of storm-tide inundation will be greater and this is mapped in the Coastal Storm Inundation Hazard data layer. Rainfall and freshwater flooding are also not included in this data, but are available separately in other geomaps layers e.g. ‘Flood Plains’, or on the Auckland Flood Viewer). The mean high water spring tide sea levels have been updated based on the mean sea level averaged over the period 2001–2019. This accounts for sea level rise that has occurred up until the effective base date of 2010, but does not include sea level rise that has occurred since that period. This is set out in the report Coastal inundation from sea-level rise in the Auckland Region (NIWA, 2023). 0.5m sea level rise increments are added on top of this in order to assess the increasing coastal inundation hazard into the future.Sea-level rise values applied currently align with the projections by the Intergovernmental Panel on Climate Change sixth assessment report (2021), and the Ministry for the Environment (2022) Interim guidance on the use of new sea-level rise projections, which updates the Ministry for the Environment Coastal Hazards and Climate Change Guidance for Local Government (2017). In MfE’s (2022) interim guidance, (excluding vertical land movement) one metre sea-level rise is projected to occur between 2095 - >2200, depending on the emission scenario used. Two metre sea-level rise is projected to occur in the longer term (beyond 2150).MfE’s (2022) Interim guidance recommends the inclusion of vertical land movement (VLM) in relative sea level rise considerations. These are not included in the above sea level rise predictions due to the high VLM variability across the region. Vertical land movement is generally predicted to increase the rates of relative sea level rise for the Auckland region so should also be incorporated in planning and design.Refer to Interim guidance on the use of new sea-level rise projections | Ministry for the Environmentand NZ Sea Risefor more information on MfE’s interim guidance on sea level rise and vertical land movement.Mean high water spring tides are used to define the Coastal Marine area boundary within Auckland’s Unitary Plan. The inundation mapping is based on the Digital Elevation Model ground levels surveyed by aerial LiDAR between 2016-2018.Lineage:Coastal inundation from sea-level rise in the Auckland Region (NIWA, 2023) (Note: The studies informing this mapping of coastal inundation generally used Auckland Vertical Datum 1946. Auckland Council is now transitioning to using New Zealand Vertical Datum 2016.)Update Cycle:Adhoc when improved data becomes available.This data is available to the public on the Geomaps viewer and on Auckland Council Open Data portaland some coastal flood mapping is copied into LIM reports.

Predicted natural flow path of water over the ground when the stormwater network is overloaded. This layer is a dissolved version of the OverlandFlowPaths layer where each segment is classified by its upstream catchment area, which will fall into one of the following ranges:2000-4000 m24000 m2 to 1 Ha1–3 Ha3–100 Ha>100 HaThe layer is an update of an existing layer and was created by WSP Opus in 2019.LineageThe OverlandFlowPaths layer is based on Auckland Council’s latest LiDAR data, which was flown in 2016 and became available after processing in 2018. The 2016 LiDAR data had a much higher point density (4 points per m2) than previous versions, which should result in more accurate flow paths. The layer was generated using the D8 flow model algorithm in ArcGIS. Creation dateFinalised in July 2019Update cycleWhenever Auckland Council’s LiDAR has been updated, if possible.Contact PersonMahesh PatelContact PositionSenior Healthy Waters SpecialistDisclaimer:In using the Catchments and Hydrology data set, you acknowledge that you have read, understood and agreed to the disclaimers below.The flood plains and flood sensitive area data layers are generated from catchment level modelling based on the datasets, requirements and technology available at the time of model build. They are compiled regional layers with varied data uncertainty and currency, which may directly impact data accuracy for the area of interest. The information provided therefore does not preclude the need for appropriate site-specific assessment and cannot be construed as an endorsement or approval of any development by Auckland Council.The Catchments and Hydrology data set is updated regularly when new information becomes available. As such, downloading and copying activities may result in data invalidity.Whilst due care has been taken in producing the Catchments and Hydrology data sets, Auckland Council gives no warranty as to the accuracy and completeness of any information given and accepts no liability for any error, omission or use of the information.

Abstract: The Coastal Inundation dataset maps the extent of sea water coverage expected around the coastal areas of the Auckland Region during storm events. It replaces the existing inundation extent currently (July 2018) published on Geomaps. The new data published has been derived from analysis carried out by NIWA in 2016/2017.A description of the derivation of the data is here: U:\COO\IES\STW\SW CAMP\Flood Planning Team\Coastal Inundation Analysis\DELIVERY FILES 2017\Stage III\Onde Drive Folder\CoastalInundation\MemoDeliveryReport_Final.pdfLineage: The flood levels derived by NIWA in the report Coastal Inundation by Storm Tides and Waves in the Auckland Region. June 2016. Technical Report 2016/2017 (Part 2)were used to establish the inundation water levels expected around the region. These levels were projected onto the land topography to establish the extent of coastal flooding.The land topography was derived from the 2013 LiDAR survey or 2006 LiDAR survey. The additional analysis of the Parakai Harbour area (described in Part 3 of the above report) was not published, as a higher density of LiDAR land topography is expected to be available in 2018, which will improve the accuracy in this area when it becomes available.Update Cycle: Adhoc when improved data becomes available.This data is available to the public on the Geomaps viewer and is copied into LIMs

The East Cape has a history of “hits” from decaying tropical cyclones causing widespread flooding and disruption. There are also other events that are more localised and result from a weather system dumping a large volume of water in a small area. A recent study showed that there is a trend of less of these events, but when they occur more rain falls. Most areas north of Ruatoria have a higher average rainfall than the south of the district and can cope with high rainfall events. The Waikura Valley for example can get 200mms in a 24 hour period without any adverse effects. The populated areas likely to be worst affected in a large event are the Poverty Bay Flats, Te Karaka and the area just north of Tolaga Bay. More intense localised events such as the 1985 Ngatapa flood and the 1977 Glenroy flood also caused substantial damage. Most of the Poverty Bay Flats, during inundation, is not subject to fast flowing water but huge areas are subject to ponding, which after the water recedes, will leave thick layers of silt damaging pasture and fences. In the city a number of riverbank properties are at risk. Extensive flooding depends upon the tides, potential overflow from the Waipaoa River, storm surges and the flood-peak times of the Taruheru and Waimata Rivers.