Regional Flood Exposure Model

The map shows the 1% AEP RCP 8.5+. This is a representation of severe flood hazard exposure, with significant climate change impacts. The undefended case removes levees from the model. This gives a representation of the population at risk. Defences can be breached, which is why this is important to consider for exposure analysis for planning and emergency management. The ground survey or Digital Elevation Model (DEM) used in this model is derived from LiDAR captured in 2013/2014 with a 1m horizontal resolution. Modelling accuracy is expected to be reduced around features (channels, embankments) smaller than 20m, and is mapped to a 5m resolution. The model does sample the LiDAR at a higher resolution to conveyance characteristics of the higher resolution LiDAR. A static tidal boundary has been adopted for this assessment which does not take varying tidal conditions into consideration, but does consider extreme sea level impacts like storm surge. The model includes stormwater flooding but is less accurate in urban catchments. This model considers all catchments not just those with Greater Wellington flood protection schemes in place.