The district plan’s mapped tsunami inundation extent, the
4,435 hectares of low coast,
estuary edge and river mouth that NIWA’s modelling says the sea
could reach. Not a prediction of any wave, the line the plan
draws so its coastal rules know where to ask.
Inundation areas
867
Mapped extent
4,435
hectares
Modelled by
NIWA
for Environment Canterbury
Newest model
2014
ECAN Report R14/78
Where the sea could come
The whole mapped extent in tide blue, the
estuary, the coast, and the rivers' mouths. A modelled reach,
not a prediction: hover any patch for the report it came from.
The signed evacuation routes draw in red, the council's marked
ways out of the reach. The suburbs by share of outline inside
the line are below, and a point’s own answer is at
/before.
The marked ways out
The council’s signed tsunami evacuation routes,
14 lines, about 101 km of road out of the reach.
On the day the instruction is the answer, not the map.
FerrymeadFerry Road · 5.9 km
Heathcote ValleyBridle Path Road - Tunnel Road · 9.2 km
The plan carries two reports, the extent each
mapped, counted separately.
ECAN Report R14/78 2014835 areas · 2.3K ha835 areas · 2,329 ha
ECAN Report R12/38 201232 areas · 2.1K ha32 areas · 2,106 ha
The suburbs in the reach
By share of outline inside the mapped extent,
read from a sampled join, so a sliver still counts. The coastal
and estuary suburbs carry the line; the hills don’t.
The district plan’s mapped tsunami inundation extent, 867 polygons covering 4,435 hectares of low coast, estuary edge and river mouth that NIWA’s modelling says the sea could reach. The plan carries it for its coastal-hazard rules: inside the line, some building work faces an extra question.
Is this the evacuation-zone map?
No, a different map for a different job. The coloured zones people evacuate from are the civil-defence map, drawn wider on purpose. This is the plan’s inundation extent, the ground the model says water could reach, used for land-use rules. Check the evacuation zones separately if what you need is "do I leave".
How sure is the line?
It is a model, not a memory. Most of it comes from NIWA’s ECAN Report R14/78 2014 modelling (NIWA), a credible extent drawn from scenarios, not a promise about any wave. Ground just outside the line is not certified safe; ground inside is not certified doomed.
What does the zone do to a property?
Inside the mapped extent the plan’s coastal-inundation rules apply, floor levels, foundations and some new building work get an extra look at consent time. It narrows what you can assume, it does not forbid the build.
The record behind this
Christchurch City Council’s open data, the DistrictPlanB
service’s DPTsunamiInundation layer, the operative plan’s mapped
inundation extent, modelled by NIWA for Environment Canterbury.
This is the plan’s map, not the civil-defence evacuation zones,
the zones people leave from are drawn wider, on purpose. The
rivers' own flood history is at /floods,
the liquefied ground at /liquefaction,
and the qualifying matters the coast carries at
/matters.