Table 20: Flood Emergency Response Classifications (Reference 1

9.7 Flood Emergency Response

Flood Emergency Response pertains to a set of classifications that advise how a community is affected by flooding and informs the decision-making process during a flood event. These classifications consider the full range of flood behaviour up to the PMF event. Factors such as isolation, evacuation routes, effective warning times, the rate of rise of floodwaters and the duration of isolation are considered when determining the classification.

In the current study, Flood Emergency Response classifications have been undertaken in accordance with the Australian Emergency Management Handbook 7 (Reference 1) and are detailed in Table 20.

Table 20: Flood Emergency Response Classifications (Reference 1)

Primary Classification Secondary Classification Tertiary Classification

Flooded (F) The area is flooded in the PMF

Not Flooded Isolated (I) Isolated from community evacuation facilities by floodwater and/or impossible terrain as waters rise during events up to the PMF. Likely to lose services during a flood. Submerged (FIS) Where all land in isolate area will be fully submerged in PMF after becoming isolated. Elevated (FIE) Where there is a substantial amount of land in isolated areas elevated above the PMF.

Exit Route (E) Areas that are not isolated in the PMF and have an exit route to community evacuation facilities. Overland Escape (FEO) Evacuation from the area relies upon overland escape routes that rise out of the floodplain Rising Road (FER) Evacuation routes from the area follow roads that rise out of the floodplain.

Indirect Consequence (NIC) Areas that are not flooded but may lose services. Flood Free Areas that are not flood affected or indirectly affected by flooding.

Emergency response classifications typically pertain to areas impeded by mainstream flooding where there are significant warning times allowing for preventative action to be taken. In areas predominantly affected by overland and flash flooding, such as Exile Bay, preventative action cannot be undertaken due to a lack of flood warning time (effectively zero). In the event of flooding, generally, residents are safest indoors and should avoid walking or driving in flood waters. Therefore, in Exile Bay, emergency response classifications will be most useful for agencies, such as the SES, as a response to the aftermath of a flood.

Figure 38 presents the emergency response classifications for Exile Bay. Much of the catchment was found to be Flood Free, Indirect Consequence or Flooded with a Rising Road Exit Route (see Table 20). Along the Main South Drain and the Central Drain there are large areas of Flooded, Isolated and Submerged (FIS) or areas with an Overland Escape Exit Route (FEO).

In areas of FEO, road access would not be possible for the duration of the flood event however access can be achieved overland (i.e. on foot). Due to the short duration of these events (for much of the catchment – peak duration will be measured in minutes), residents in these areas would generally be safest waiting for floodwaters to recede before exiting their properties.

In areas of FIS, road access would be cut prior to properties being inundated by floodwaters. The flooding Hotspots assessed in Section 12 are located within areas classified as FIS.

Flood Emergency Response classifications are derived for the PMF flood event only. Due to the flash flood nature of the catchment the event magnitude is unknown at the time of the event. If those responding to a flood used Emergency Response classifications derived for a smaller event than that which is occurring, these classifications may be incorrect. A key example of this is the classification of Flooded, Isolated, Elevated (FIE) and Flooded, Isolated, Submerged (FIS). The classifications derived for a smaller event may define areas as FIE meaning that they lose flood access however they are not inundated. In larger events however, these FIE areas may become inundated meaning that their classification changes to FIS and as such their affectation is more severe. Thus, given the flash flood nature of the catchment and the unknown event magnitude, it is precautionary to only use the PMF emergency response classifications.