Nelson City Council (NCC) engaged Tonkin & Taylor (T+T) to undertake a high level or first-pass coastal inundation assessment for Nelson City, followed by a more detailed and dynamic assessment.

Areas inundated under extreme static inundation levels have been mapped using two methods:

• a simple bathtub model (all land below a specified elevation shown as inundated); and

• a connected bathtub model where areas are flooded only where they connect to the coastalwater body.

Areas that are inundated but disconnected from the coastline (e.g. all land below MHWS), aremapped with a different colour to show the potential total inundated area if the disconnected areasare hydraulically connected (e.g. via culverts).

Digital elevation models (DEMs) have been constructed for Nelson City using NCC LiDAR data from2014/2015. DEMs have been constructed at a 0.5 m grid resolution and represent the bare earth (i.e.with buildings and vegetation removed).