Appendix D_Engineering Report

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5.4.4 Design Storms
As defined in Noosa Council’s Planning Scheme the following design storms were adopted:
    1. Minor Drainage System: 10 year ARI statistical flood (Q10 storm), and;
    2. Major Drainage System: 100 year ARI statistical flood (Q100 storm).

5.4.5 Rainfall Intensity
Rainfall intensities for this study were obtained from the IFD chart for the Noosa Region
calculated from AR&R, 1987 and sourced from the Australian Bureau of Meteorology.

5.4.6 Times of Concentration
Times of concentration (tc) were calculated as defined in Section 4.06 of the QUDM. Refer to
Table 5-1 for the adopted tc’s and to Appendix G for tc calculations.

                                      Table 5-1 – Adopted tc values
                                   Pre Development         Post Development
                                       tc (mins)                tc (mins)

                                          11.2                       6.9


5.4.7 Runoff Coefficients
The 10 year runoff coefficient’s (C10) were determined as defined in Section 4.05 of the QUDM.
Refer to Table 5-2 below for the adopted C10 values.

                                      Table 5-2 – Adopted C10 Values

                                          Property State                   C10

                                        Pre-development                    0.35
                                        Post-development                   0.83


5.4.8 Peak Flows
Refer to Table 5-3 for a summary of the predicted minor and major discharge rates for pre- and
post-development conditions and to Appendix G for the Rational Method calculations.

                                Table 5-3 – Pre and Post-Development Peak Flows

                             Property State                Q10 (m3/s)             Q100 (m3/s)

                           Pre-development                   0.190                  0.331
                           Post-development                  0.543                  0.942


It is evident that there will be an increase between the pre-development and post-development
peak discharge flow rates.




Engineering Services Assessment
Residential Development at Precinct E2, Noosa Springs, Noosa Heads