Inundation Hazard Assessment

This section presents the process in determining the inundation extents under the various sea-level rise scenarios. Two modelling approaches were adopted. In more complex areas dynamic flood models were used, these models consider overland spreading, flow through engineered structures, saline and freshwater inputs, topographic features and shore protection and use time-varying input conditions.     

For low-lying land where the mechanisms for coastal inundation are simpler, a static model was used to determine potential inundation extents. This assumes that the elevated storm-tide level will be able to overwash the shoreline or defences and flood the hinterland. This technique considers flood routes, but not the rate of overland spreading, ground absorption etc. This makes extents more conservative than may occur in reality, and represents a worst-case inundation extent for the water levels used. The assessment also considers shore protection, and under which scenario water is able to breach the shoreline.  

The mechanisms for coastal inundation throughout the study area are varied due to the differing landscapes, as shown in Table 5-1.

Table 5-1      Possible mechanisms of inundation for the coast and rivers / estuaries