5.6.3. First Event Flooded

Chart 3 Breakdown of Total Annual Average Damages by Village

Chart 4 Distribution of Residential AAD across the Villages Chart 5 Distribution of Commercial AAD across the Villages

5.6.3.First Event Flooded

In addition to estimating direct tangible costs in design flood events and determining Annual Average Damages, the damages assessment is useful in identifying the frequency of event in which residential and commercial buildings are likely to first be flooded above floor level, and identifying these buildings spatially. Figure 3 (Sheets 1-5) show all buildings in each village’s Study Area estimated to be flooded above floor, categorised by the design event in which they are expected to be subject to over-floor flooding. This information can assist in identifying areas subject to the greatest flood risk, where investment in flood mitigation works may be warranted, as well as highlight areas where planning controls (such as land use zoning and minimum floor level controls) have been implemented effectively.

Rand $630 Oaklands Boree $178,600 Creek $724,100

Morundah $194,600

Urana $225,200 Boree Creek $340,500 Morundah $148,700 Oaklands $80,300 Rand $596 Urana $118,500 Boree Creek $383,700 Morundah $45,900 Oaklands $98,400 Rand $35 Urana $106,700 DRAFT FOR PUBLIC EXHIBITION

The results are consistent with the above charts and discussion: that is, Boree Creek has the greatest number, and highest proportion, of buildings flooded above floor level, with 11 buildings subject to internal flooding in a 20% AEP event. These include two residential dwellings on Lawrence Street and a further two downstream of town, south of Urana-Boree Creek Road. Five of the seven commercial properties also flooded above floor in a 20% AEP event are located on Richmond Street, with the final two on Orara Street at the north-eastern end of town. The dwellings most at risk of over-floor flooding in Morundah are located on Milvain Drive, and are subject to flooding from overland flow from the land north of Morundah, and on the bank of Colombo Creek to the west of town. A further 7 dwellings are first subject to above-floor flooding in the 5% or 2% AEP event, while the remainder of dwellings would not be flooded until the 1% AEP event or rarer. Buildings in Oaklands are relatively safe from over-floor inundation, with majority of both residential and commercial premises not flooded above floor until the PMF event, or not flooded at all. Two low lying dwellings are flooded above floor in the 2% AEP event. A similar trend is seen in Rand, with all buildings well above Billabong Creek, and only experiencing over-floor inundation in the PMF event, if at all. In Urana, the frequency of above-floor inundation decreases with distance from Urangeline Creek. The most frequently affected buildings (flooded above floor in a 10% AEP event) are located close to the creek, on the western side of the township. No dwellings or commercial buildings are estimated to be internally flooded in a 20% AEP event. Generally, properties on the eastern side of William Street are not flooded above floor in events more frequent than an 0.5% AEP event. DRAFT FOR PUBLIC EXHIBITION