C6361-22-ENG - Feb 2023 - V1

Rational Calculations ‐ Swale Drain
Reference ‐ Chapter 4 QUDM.




Job Name.            Triller Court             CATCHMENT INFORMATION
Job No.              C6361                   LOCAL AUTHORITY                            NSC
Date                 9/05/2022               IFD INFORMATION                           Noosa
Designed             BWM                     10% AEP 60min                              65.2
Checked              MVC


   EXISTING TIME OF CONCENTRATION                              DEVELOPED TIME OF CONCENTRATION                                   COEFFICIENT OF RUNOFF
                                                                                                                             Sub‐Catchment Area (Ha) Fraction Impervious (%)      Runoff Coefficients
                     Std Inlet Time                                              Std Inlet Time         5.0        CMT No.   Pre Catch    Post Catch      Existing   Developed    Existing        Developed
                                                                                                                     1                      0.364                       60                          0.80
                                                                                                                     2
                     Slope (%)                                                   Slope (%)                           3
      SHEET FLOW




                                                                  SHEET FLOW
                     Flow Length (m)                                             Flow Length (m)                     4
                     Horton's 'n'                                                Horton's 'n'                        5
                     Flow Time (min)                                             Flow Time (min)                    Total                   0.364                       60                          0.80



                                                                                                                                                  PEAK DISCHARGE CALCULATIONS
      CHANNEL FLOW




                     Flow Length (m)                                             Flow Length (m)                               Rainfall (mm/hr)           Coefficient of Runoff   Peak Discharge (m³/s)
                                                                  PIPED FLOW



                     Fall (m)                                                    Fall (m)                           AEP       Existing    Developed       Existing   Developed    Existing        Developed
                     Flow Time (min)                                             Flow Time (min)                    63%                     95.8                       0.64                         0.06
                     Multiplier ∆                                                Multiplier ∆                       39%                     120                        0.68                         0.08
                     Flow Time (min)                                             Flow Time (min)        0.0         18%                     149                        0.76                         0.11
                                                                                                                    10%                     170                        0.80                         0.14
                                                                                                                     5%                     193                        0.84                         0.16
      CHANNEL FLOW




                     Flow Length (m)                                             Flow Length (m)                     2%                     223                        0.92                         0.21
                                                                  KERB FLOW




                     Fall (m)                                                    Fall (m)                            1%                     245                        0.96                         0.24
                     Flow Time (min)                                             Flow Time (min)
                     Multiplier ∆                                                Multiplier ∆
                     Flow Time (min)                                             Flow Time (min)        0.0
      CHANNEL FLOW




                                                                  CHANNEL FLOW




                     Flow Length (m)                                             Flow Length (m)       130.0
                     Fall (m)                                                    Fall (m)               10.0
                     Flow Time (min)                                             Flow Time (min)        1.0
                     Multiplier ∆                                                Multiplier ∆            4
                     Flow Time (min)                                             Flow Time (min)        4.0

                                                                                               Total           9
      CHANNEL FLOW




                     Flow Length (m)
                     Fall (m)
                     Flow Time (min)
                     Multiplier ∆
                     Flow Time (min)

                                     Total