Response to Information Request 10-6-2025 Overland Flow Assessment · OPW25/0042

  2.2.1       Sensitivity Results
Three sensitivity assessments were completed for the following arrangements and run for the 1% (2100) AEP events with the outcome of
these scenarios described below.

2.2.1.1 Sensitivity 1 (005) – Increased Flow Path Roughness
This sensitivity scenario, which assessed the increased roughness applied to the channel base, shows that there is a minor increase in flow
depth and hazard within the flow path, however, these changes managed well within the 0.5m freeboard applied. The flow depth in the 1%
(2100) AEP generally increases by up to 0.08m along the channel, with a maximum increase of 0.1m noted. Flood hazard in the 1% (2100)
AEP event has a maximum change of only 0.02m2/s, with hazard remaining below 0.40m2/s. An excerpt of the 1% (2100) AEP depth and
hazard maps are detailed below in Figure 2.7.




FIGURE 2.7: SENSITIVITY 1 – INCREASED FLOW PATH ROUGHNESS - 1% (2100) AEP FULLY BLOCKED – DEPTH AND HAZARD

2.2.1.2 Sensitivity 2 (005a) – Blocked RIP
This sensitivity scenario, which assessed the full blockage of the RIP, shows that there is a minor increase in flow depth and hazard within
the flow path, however, these changes managed well within the 0.5m freeboard applied. The flow depth in the 1% (2100) AEP generally
increases by up to 0.07m along the channel, with a maximum increase of 0.09m noted. Flood hazard in the 1% (2100) AEP event has a
maximum change of only 0.09m2/s, with hazard remaining below 0.40m2/s. An excerpt of the 1% (2100) AEP depth and hazard maps are
detailed below in Figure 2.8.




NOOSA CALILE I BBNE01676-0001-REP-001-1                                                                                                  14