Hydraulic Assessment 29 August 2024

QUDM Rational Method (IPWEA, 2016)

                              Project Number BBNE0000_0020                                        Project Director BB
                                Project Name 38 Barina Ct, Pomona                                Project Manager LH
                                Catchment ID                                                     Project Modeller DW                      Date modified 3/07/2024


Catchment Parameters                                                                                                           Design Event AEP (%)    Rational Method Peak Flow   WBNM Peak Flow (m3/s)       Peak Flow Difference (m3/s)   Peak Flow Difference (%)
Catchment Area (ha)                                    14.24                                                                             1                            3.6                       3.7                         0.1                          3%
Fraction Impervious (%)                                 17%           Refer relevant Local Government Planning Scheme Policy             2                            3.1                      3.15                         0.1                          2%

10-year 1-hour Rainfall Intensity (mm/h)
                                                      63.6                                                                                5                           2.3                      2.27                         -0.1                         -3%
Land Description                                Medium Density Bush Refer QUDM (2016) Table 4.5.3 & 4.5.4 (page 4-8)                     10                           2.0                                                   -2.0                       -100%
Soil Permeability                                     High          Refer QUDM (2016) Table 4.5.3 & 4.5.4 (page 4-8)                     18                           1.7                                                   -1.7                       -100%
Runoff Coefficient (-)                                0.30                                                                               20                           1.6                      1.46                         -0.1                         -8%
                                                                                                                                         39                           1.2                                                   -1.2                       -100%
Total Time of Concentration                              12                                                                              50                           1.0                      0.85                         -0.2                        -18%
                                                                                                                                         63                           0.9                      0.78                         -0.1                        -13%
Bransby-Williams
Time of Concentration (min)                                                                                                    Design Event AEP (%)    Rainfall Intensity (mm/h)   Frequency Factor (Fy) (-)
                                                      #DIV/0!         Refer QUDM (2016) Equation 4.9 (page 4-20)
Include in Total ToC?                                   No                                                                                1                          251.8                      1.2
                                                                                                                                          2                          225.3                     1.15
Modified Stream Velocity Method                                                                                                           5                          188.5                     1.05
Flow Path Length (m)                                    400                                                                              10                          166.3                       1
Travel Velocity (m/s)                                    2            Refer QUDM (2016) Table 4.6.6 (page 4-21)                          18                          147.4                     0.95
Time of Concentration (min)                             3.3                                                                              20                          142.1                     0.94
Include in Total ToC?                                   Yes                                                                              39                          119.8                     0.85
                                                                                                                                         50                          105.2                     0.83
Overland Sheet Flow                                                                                                                      63                           94.4                      0.8
Flow Path Length (m)                                      50           Refer QUDM (2016) Table 4.6.4 (page 4-13)
Surface Condition                              Average Grassed Surface Refer QUDM (2016) Figure 4.4 (page 4-13)
Hortons 'n' (-)                                         0.045
Average Surface Slope (%)                                30%
Time of Concentration (min)                              9.0           Refer QUDM (2016) Equation 4.5 (page 4-14)
Include in Total ToC?                                    Yes