{"help": "https://data.gov.au/data/api/3/action/help_show?name=package_show", "success": true, "result": {"archived": false, "author": "Northern Beaches Council", "author_email": null, "contact_point": "manly@northernbeaches.nsw.gov.au", "creator_user_id": "c2fbbe4a-4ba0-4945-808b-67454605a4cf", "duplicate_score": 2, "geospatial_topic": [], "id": "5cdf5bf8-b56c-4815-9bdc-1087ffd52b57", "isopen": false, "license_id": "cc-by", "license_title": "Creative Commons Attribution 3.0 Australia", "license_url": "http://creativecommons.org/licenses/by/3.0/au/", "maintainer": null, "maintainer_email": null, "metadata_created": "2026-01-21T16:35:39.986380", "metadata_modified": "2026-01-21T16:35:46.138003", "name": "nsw-fdp-dee-why-cbd-flood-study-update-report", "notes": "Warringah Council has identified a need to prepare a drainage and flood mitigation plan\nfor the Dee Why Town Centre. The plan is needed to accompany the Dee Why Town\nCentre Masterplan and Public Domain Improvements Plan that has been prepared to\nguide future redevelopment of the town centre.\nCouncil recognised that its existing 1D hydraulic model of the Dee Why CBD has\nlimitations and instead decided to upgrade the floodplain model to a1D/2D model to\nprovide a clearer understanding of the flood characteristics in and around Dee Why\nCBD.\nIn view of Council\u2019s aim to better understand overland flooding of the Dee Why CDB, it\nwas decided to assemble both a SOBEK model and an xpswmm2D model of the study\narea to allow the estimated overland flood depths, velocities of flow and hazards to be\ncompared and to identify any significant differences in overland flooding within the study\narea.\nThe SOBEK model was assembled based on a 1m x 1m grid of surface elevations that\nwas created using 12D and the ALS data supplied by Council. Buildings were\nrepresented by raising the surface elevations of all buildings within the building outlines\naround 10 m higher than the surrounding terrain.\nThe xpswmm2D model of the Dee Why CBD was also based on the ALS data supplied\nby Council. The MapInfo building outline was imported into xpswmm2D and was used\nto \u201cnull\u201d the grid points within the building outlines. The \u201cnulling\u201d of these grid points\neliminated them from the computation scheme on the basis that flow was excluded from\nbuildings.\n\nBoth models were run for both the 100 yr ARI and PMF events using the local inflow\nhydrographs obtained from Council\u2019s MIKE-11 model of the Dee Why CBD. Overland\nflood depths, velocities, velocity x depth and provisional flood hazards in the 100 yr ARI\nand PMF events were estimated in the Dee Why CBD.\n\nIt was concluded that the SOBEK model and xpswmm2D model estimate similar 100 yr\nARI and PMF overland flood levels and patterns of flow.\nIt was concluded that around 60% of the estimated 100 yr ARI flood levels adjacent to\nproperties are equal to or lower than the 100 yr ARI flood levels currently adopted by\nCouncil. Conversely around 40% of the estimated 100 yr ARI flood levels are higher than\nthe 100 yr ARI flood levels currently adopted by Council.\n\n10% of the estimated 100 yr ARI flood levels adjacent to properties are more than\n0.25 m lower than currently adopted by Council. A further 10% of the estimated 100 yr\nARI flood levels adjacent to properties are more than 0.33 m higher than currently\nadopted by Council.\nIt was noted that overland flows in sections of Oaks Avenue, Howard Avenue, Dee Why\nParade and Avon Road exceed the velocity x depth criterion for vehicular stability.\nSimilarly the sections of the overland flowpath located above the trunk drainage line\nbetween Oaks Avenue and Howard Avenue and between Dee Why Parade and\nRichmond Avenue also exceed the velocity x depth criterion for pedestrian and vehicular\nstability.\n\nSimilarly these areas were also assessed to have a provisional high hazard rating.\nIt was concluded that around 80% of the estimated PMF flood levels adjacent to\nproperties are equal to or lower than the PMF flood levels currently adopted by Council.\n\nConversely around 20% of the estimated PMF flood levels are higher than the PMF flood\nlevels currently adopted by Council. 10% of the estimated PMF flood levels adjacent to\nproperties are more than around 0.6 m lower than currently adopted by Council. A\nfurther 10% of the estimated PMF flood levels adjacent to properties are more than 0.16\nm higher than currently adopted by Council.\n\nIt was noted that the sections of Oaks Avenue, Howard Avenue, Dee Why Parade and\nAvon Road that exceed the velocity x depth criterion for vehicular stability significantly\nincrease in a PMF. Similarly almost all the overland flowpath located above the trunk\ndrainage line between Oaks Avenue and Richmond Avenue also exceed the velocity x\ndepth criterion for pedestrian and vehicular stability in a PMF.\n\nSimilarly these areas were also assessed to have a provisional high hazard rating in a\nPMF.\n\nStudy Area\n\nThe Study Area, which comprises of the southern upper region of the Dee Why Lagoon\nSouth catchment, is presented in Figure 1 in report.\nThe catchment draining to and through the Dee Why CBD is shown in Figure 2 in report. It has a\ntotal catchment area of 156 ha at its point of discharge to Dee Why Lagoon.\nThe landuse is largely residential outside of the Dee Why CBD.", "num_resources": 1, "num_tags": 3, "organization": {"id": "944317c5-4cd7-4f5d-afdf-3f24da0c35f7", "name": "northern-beaches-council-datansw", "title": "Northern Beaches Council", "type": "organization", "description": "The Northern Beaches Council is a recent LGA on Sydney's northern beaches formed from the merger of Manly, Pittwater and Warringah councils. \r\n\r\nhttp://www.northernbeaches.nsw.gov.au/\r\n\r\nFlood Studies, Plans and Maps available:\r\nhttp://www.pittwater.nsw.gov.au/property/natural_hazards/flooding/where_does_it_flood/flood_studies_and_plans\r\n\r\nCareel Creek\r\nAvalon to Palm Beach Flood Risk Management Study and Plan - current project.\r\nCareel Creek Catchment Flood Study - July 2013\r\nCareel Creek Floodplain Risk Management Plan November 2002 \r\nCareel Creek Floodplain Management Study Sept 2000 \r\nCareel Creek Drainage Catchment Flood Study June 1999 - superseded\r\n\r\nGreat Mackerel Beach\r\nGreat Mackerel Beach Floodplain Risk Management Study and Plan - November 2010\r\nGreat Mackerel Beach Flood Study September 2005\r\n\r\nMona Vale/Bayview\r\nMcCarrs Creek, Mona Vale and Bayview Flood Study - current project\r\nMona Vale - Bayview Flood Study May 2002\r\n\r\nNarrabeen Lagoon\r\nNarrabeen Lagoon Flood Study - September 2013\r\nNarrabeen Lagoon Floodplain Risk Management Plan Vol 1 Pittwater December 2002\r\nNarrabeen Lagoon Floodplain Management Study 1992\r\n\r\nNareen Creek (subcatchment of Narrabeen Lagoon)\r\nNareen Creek Flood Study September 2005 - superseded\r\n\r\nWarriewood Valley (subcatchment of Narrabeen Lagoon)\r\nWarriewood Valley Flood Study April 2005 - superseded\r\nWarriewood Valley Flood Study Addendum 1 July 2005 - superseded\r\nWarriewood Valley Urban Land Release Water Management  Specification - February 2001\r\n\r\nNewport\r\nNewport Beach Floodplain Risk Management Study & Plan February 2004\r\nNewport Beach Flood Study March 2002\r\n\r\nOther Areas\r\nPittwater Overland Flow Mapping and Flood Study - October 2013\r\nMcCarrs Creek, Mona Vale and Bayview Flood Study - current project\r\nAvalon to Palm Beach Flood Risk Management Study and Plan - current project\r\n", "image_url": "", "created": "2025-06-24T03:44:34.804318", "is_organization": true, "approval_status": "approved", "state": "active"}, "original_harvest_source": {"site_url": "https://data.nsw.gov.au/data/", "href": "https://data.nsw.gov.au/data/dataset/nsw-fdp-dee-why-cbd-flood-study-update-report", "title": "DataNSW"}, "original_name": "nsw-fdp-dee-why-cbd-flood-study-update-report", "owner_org": "944317c5-4cd7-4f5d-afdf-3f24da0c35f7", "private": false, "promotion_level": "0", "remote_last_updated": "2026-01-14 04:49:37.332132", "spatial": "{\"type\": \"Point\",\"coordinates\": [147.0179,-32.1618]}", "spatial_coverage": "New South Wales (NSW81093)", "state": "active", "temporal_coverage_from": "2025-12-17 01:15:56.738863", "temporal_coverage_to": "2007-12-01 00:00:00", "title": "Dee Why CBD Flood Study Update", "type": "dataset", "unpublished": false, "url": null, "version": null, "extras": [{"key": "harvest_object_id", "value": "3b81fe14-ccb8-4853-8a1a-f87b0634e929"}, {"key": "harvest_source_id", "value": "9ebac586-8e51-4904-9f6c-d9b79726659a"}, {"key": "harvest_source_title", "value": "DataNSW"}], "resources": [{"cache_last_updated": null, "cache_url": null, "created": "2026-01-14T04:49:37.370546", "datastore_active": false, "datastore_contains_all_records_of_source_file": false, "format": "HTML", "hash": "", "id": "1193bed7-abf3-4812-b85e-5b031987161c", "last_modified": null, "metadata_modified": "2026-01-21T16:35:39.982685", "mimetype": null, "mimetype_inner": null, "name": "Dee Why CBD Flood Study Update", "package_id": "5cdf5bf8-b56c-4815-9bdc-1087ffd52b57", "position": 0, "resource_type": null, "size": null, "state": "active", "url": "https://flooddata.ses.nsw.gov.au/dataset/4ffbb15e-5ecb-4bb4-bc28-d7a3fdeeefb6/resource/2cd9e883-850e-4a72-96bd-d1d5ef811e06", "url_type": null, "zip_extract": false}], "tags": [{"display_name": "Dee Why", "id": "256d8bb3-5161-4a52-bc4d-e826fc4cd5fe", "name": "Dee Why", "state": "active", "vocabulary_id": null}, {"display_name": "hydraulic model", "id": "5ea1bf91-c991-4e1b-808e-2528b9741aa5", "name": "hydraulic model", "state": "active", "vocabulary_id": null}, {"display_name": "hydrologic model", "id": "306ddc3f-3866-4055-8fd7-0e4cd32a2a1a", "name": "hydrologic model", "state": "active", "vocabulary_id": null}], "groups": [], "relationships_as_subject": [], "relationships_as_object": []}}