Swmp

Spreadsheet based on QUDM 2017, Section 4.3 - "The Rational Method"



      Project Address                        65 & 67 Elanda Street, Sunshine Beach




                                        EXISTING USE                                                                                                                             PROPOSED USE
                              Co-efficent of Run-Off Calculation                                                                                                          Co-efficent of Run-Off Calculation
      Catchment Name                       Area (m2)             Co-efficent of Discharge                                                        Catchment Name                       Area (m2)                   Co-efficent of Discharge
          Impervious                            121                                0.900                  Table 4.5.3 (a) of QUDM (2017)             Impervious                          695                               0.900             Table 4.5.3 (a) of QUDM (2017)
           Pervious                             899                                0.700                  Table 4.5.3 (b) of QUDM (2017)              Pervious                           325                               0.700             Table 4.5.3 (b) of QUDM (2017)




                     Total Area              1019.8                                                                                                          Total Area               1019.8
                                          Adopted C10 :                           0.7237                  Table 4.5.3 of QUDM (2017)                                               Adopted C10 :                          0.8363             Table 4.5.3 of QUDM (2017)



Tc (min.) :                                       8                  Figure 4.4 of QUDM (2017)                                             Tc (min.) :                                    6                    Figure 4.4 of QUDM (2017)
Area (ha) :                                   0.10198                (10,000m2 = 1 ha)                                                     Area (Ha) :                                0.10198                  (10,000m2 = 1 ha)




         Flood Event                         Existing                      Post Development                                    RAINFALL INTENSITY                          Peak Outflow Capacity (m3/s)           Peak Inflow Rate (m3/s)             Difference (m3/s)
              AEP (%)                       Cy = Fy x C10                     Cy = Fy x C10                            Existing                 Post Development                   Qo (Existing)                  Qi (Post Development)               Qi-Q0 (Post - Pre)
               63%                             0.579                               0.669                            111.2 mm / hr                  120.4 mm / hr                        0.018                              0.023                            0.005
               50%                             0.615                               0.711                            125.4 mm / hr                  135.8 mm / hr                        0.022                              0.027                            0.005
               18%                             0.688                               0.794                            169.2 mm / hr                  184.4 mm / hr                        0.033                              0.041                            0.009
               10%                             0.724                               0.836                             198 mm / hr                    216 mm / hr                         0.041                              0.051                            0.011
                5%                             0.760                               0.878                            225.2 mm / hr                  246.4 mm / hr                        0.048                              0.061                            0.013
                2%                             0.832                               0.962                             260 mm / hr                    286 mm / hr                         0.061                              0.078                            0.017
                1%                             0.868                               1.000                            285.6 mm / hr                  315.2 mm / hr                        0.070                              0.089                            0.019




                                     Where Coefficients of Runoff calculated from the above equation                                                                                Rational Method                    Rational Method
                                  exceed 1.00, they should be arbitarily set to 1.00. QUDM 2017 Section                                                                              Q = CIA / 360                      Q = CIA / 360
                                                                    4.5