EagFirRsp

impacts in the 10 to 100 year events are completely mitigated.

Nett Result: Useful mitigation; with benefits in the major storms but minor (inconsequential) disbenefits in the
minor storms.

Table 7: Water Levels At Node N14B At The Tait Street Sag
 Event                Pre-Development    Post Development
 AEP (ARI)             EL (m)              EL (m)
 AEP 1% (100 yr)       3.14               3.12
 AEP 2% (50 yr)        3.12               3.11
 AEP 5% (20 yr)        3.11               3.09
 AEP 10% (10 yr)       3.09               3.07
 AEP 20% (5 yr)        3.05               3.05
 AEP 50% (2 yr)        2.98              2.99
 AEP 67% (1yr)         2.95               2.96


Water Levels At Node 11, Midway Along The Creek Between Tait Street And The Caravan Park.

Node 11 is located in the floodway of the creek. The pre- and post-development water levels are summarised
in Table 8, below.

In the absence of any mitigation, the increased imperviousness of the development site would adversely affect
the water levels in the creek, across the full range of AEP, and this would be further affected (either way) by
the relative changes in hydrograph timing, particularly with respect to the interaction of hydrograph timing
from the intensively developed Riverlands and Noosa Nursing centres alongside the creek.

With the basin in place, the impacts in the 5 and 10 year storms are limited to an afflux of 0.01 metre. In the
other storms, impacts are completely mitigated.

Nett Result: Useful mitigation; but with some minor (inconsequential) disbenefits in the moderate storms.

Table 8: Water Levels At Node N11, Midway Along The Creek
 Event                Pre-Development    Post Development
 AEP (ARI)             EL (m)              EL (m)
 AEP 1% (100 yr)       2.41               2.40
 AEP 2% (50 yr)        2.35               2.35
 AEP 5% (20 yr)        2.29               2.29
 AEP 10% (10 yr)       2.21               2.22
 AEP 20% (5 yr)        2.11               2.12
 AEP 50% (2 yr)        1.96               1.95
 AEP 67% (1yr)         1.91               1.91

Water Levels And Flow Rates At Node N2, At The Point Of Discharge To The Caravan Park.

The post-development model without the basin indicated that the development would increase the flow rates at
this location by as much as 8 percent in a 1 year storm, and by lesser amounts at other storm severities.




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BSM Doc File EagFirResp.Doc