Floodplains are areas predicted to be covered by flood water as result of a
rainstorm event of a scale that occurs on average once every hundred years.
These areas have been produced from hydraulic modelling. The floodplain contains
the most up to date information for each of the 23 Stormwater Catchments in the
Auckland region. Summary data for each catchment is attributed against each
Flood prone areas are topographical depressions. The areas occur naturally, or
are created by dammed gullies created by man-made features such as roads and
railway embankments. The flood prone extent is the area water will pond up to in
a 100-year ARI extreme rainfall event assuming the outlet to the topographical
depression is blocked.
Flood Sensitive Areas are areas adjacent to the 100yr ARI floodplain that are
within 0.5 m of the predicted 100-year ARI flood level. These mapped areas are to
ensure the appropriate planning rules are considered for properties developing
adjacent to the floodplain