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Coastal management district mapping methodology

The following methodology is used to decide which lots to include or exclude from the Coastal Management District. Geographical Information System (GIS) software is used to apply the mapping rules.

The mapping rules are:

Included (automated process):

  • lots that intersect the declared Erosion Prone Area (EP Area) layer
  • all tidal areas to the limit of state water

Excluded (automated process):

  • lots that are not base parcels (e.g. stacked parcels for a high-rise, easements)
  • non-state land tenure lots less than 2000m2 in size
  • lots that are intersected by the EP Area by less than 50m2 in total area or less than 2m linear distance
  • land lots forming part of an approved canal estate (dry land only)
  • lots in or adjoining a non-tidal artificial waterway (dryland marina, lakes etc.).

Excluded (visual determination):

  • lots landward of significant development such as formed roads or houses which would be protected if threatened by sea erosion
  • lots forming part of enclosed marinas with significant building/marine infrastructure development
  • road sections extending outside the EP Area
  • lots with intensive industrial or building development where future redevelopment potential and coastal resources present is very low
  • industrialised port areas—behind revetment or significantly developed and where future redevelopment potential and coastal resources present is very low
  • state boat harbours—behind revetment or significantly developed
  • maritime development—behind revetment or significantly developed
  • large lots where the extent of the EP Area within the lot is insignificant
  • developed lots which were part of a reconfiguration where part of the original lot was surrendered to the state for beach protection and coastal management purposes
  • lots where previous negotiations concluded in the lot being removed from the CMD
  • lots with sea level rise only is mapped and which are generally no more than 2 tenured lots back from the coast, taking into account the peri-urban form, maintenance of a consistent coastline retreat scenario, and whether the lots could participate in natural coastal processes
  • lots where tidal flow is controlled through artificial waterways/works such as tide gates.

Excluded (comparative risk assessment removal processes):

  • lots with a high terrestrial flood risk—determined either by:
    • terrestrial flood height—where 1% Annual Exceedance Probability (AEP) water level is significantly above storm tide inundation levels (greater than 3m above normal water levels has been set as a nominal value)
    • morphological criteria assessment—requires rivers to be divided into morphological units of delta plains, flood plains and incised river channels and an assumption of terrestrial flooding being the dominant natural hazard in the incised channel section of the river and coastal hazards being the dominant natural hazard on the low lying flat landforms closer to the open coast.

Note: These rules generally apply greater than 5km from the open coast river entrance.

Included:

  • lots that have known high erosion vulnerability or significant coastal management issues
  • lots where all or part of the lot is below the level of highest astronomical tide
  • all lots seaward of or intersected by a Coastal Building Line regardless of size or tenure
  • all lots intersected by or wholly seaward of the Gold Coast A-line seawall alignment.