The results of the overtopping assessment are presented in Table 6-7. Discharges are presented in units of litres per second per metre (L/s/m). The results show that under the higher sea-level rise scenarios, the overtopping hazard of the structures increases.
Table 6-7 Lonsdale Bight Overtopping
Location |
Overtopping discharge (L/s/m) |
|||||
|---|---|---|---|---|---|---|
1% AEP + 0.0m m SLR |
1% AEP + 0.2 m SLR |
1% AEP + 0.5 m SLR |
1% AEP + 0.8 m SLR |
1% AEP + 1.1 m SLR |
1% AEP + 1.4 m SLR |
|
1 |
29.1 |
120.2 |
fail |
fail |
fail |
fail |
2 |
14.5 |
63.3 |
fail |
fail |
fail |
fail |
3 |
38.6 |
172.4 |
fail |
fail |
fail |
fail |
4 |
0.003 |
0.2 |
5.7 |
62.6 |
fail |
fail |
5 |
0.00 |
0.002 |
0.1 |
2.2 |
15.3 |
69.8 |
|
Key: 0.1 L/s/m = mean discharge for pedestrian safety 1 - 50 = unsafe for pedestrians 50 – 200 = very hazardous to people and vehicles, some pavement or promenade damage >200 L/s/m = damage to paved or armoured promenade behind seawall (this could be considered a discharge that would fail a structure). N.B. The results assume the condition and the elevation of the current structures are maintained. | ||||||
The inundation extent for Queenscliff (Fisherman’s flats) under the 1% AEP storm tide in combination with various sea-levels is presented in Figure 6-18. This shows that under a present day inundation event, there is the potential for saline inundation of Fisherman’s Flats. Note, the mechanism for flooding here will be overwashing of the very low-lying shoreline near Bay and Bridge St at Fisherman’s Flats, rather than via the front beach or marina area, which are at greater elevations than Fisherman’s Flats. Only under the higher sea-level rise scenarios is there the potential for flooding via these flowpaths.
The inundation extents for Lakers Cutting are in Figure 6-19. The events under which inundation occurs at select locations, identified by the red dots in Figure 6-19, have been listed in Table 6-8. The most significant impact of a 1% AEP storm-tide within Swan Bay is that shoreward of the Marine Discovery Centre and sections of Murray Road would both be inundated at the present day sea-level. The Marine Discovery Centre itself should avoid flooding below a 0.8 m rise in sea-level but the actual floor levels of the building would have to be verified to be certain. The Bellarine Highway comes under threat in a 1% AEP event with 0.5 m SLR, however, note that the road is low lying and local rainfall runoff coupled with saline inundation may cause flooding in lower events. The stormwater infrastructure should be assessed to ensure the risk of this is minimised. A figure showing the timing of inundation for Lakers Cutting is shown in Figure 6-20. This will aid in informing subsequent risk assessments.
Table 6-8 Critical inundation locations identified in the Lakers Cutting model
| Location | Event Resulting in Inundation |
|---|---|
| Murray Road | 1 % AEP at present day sea-level |
| Shoreward of Marine Discovery Centre | 1 % AEP at present day sea-level |
| Bellarine Highway | 1 % AEP and 0.5 m SLR |
| Emily Street | 1 % AEP and 0.8 m SLR |
| Flinders Street | 1 % AEP and 1.1 m SLR |
Inundation for Swan Bay is shown in Figure 6-21 for the south western end, and Figure 6-22 for the northern end.
Methodology - Inundation and Overtopping Hazard Assessments
Implications for Coastal Management
