Glen - REC13/0146 Flood Study BSM 30 April 2014. Email 2 Attachment 2

Table 11     URBS / Rational Method Peak Flow Calibration (m3/sec) For Post-Development Scenario
             (Refer Figure 5 For Subarea Locations)
 Subareas        1year        2 year        5 Year        10 Year        20 year        50 year       100 Year
    7         0.30 / 0.30   0.37 / 0.36   0.56 / 0.54   0.68 / 0.67    0.81 / 0.79    1.00 / 1.00    1.14 / 1.15
    8         0.05 / 0.05   0.06 / 0.06   0.10 / 0.09   0.12 / 0.11    0.14 / 0.13    0.17/ 0.17     0.19 / 0.19
    9         0.13 /0.14    0.17 /0.16    0.27 / 0.25   0.33 / 0.30    0.39 / 0.36    0.47 / 0.46    0.53 / 0.53
  10-18       0.19 / 0.20   0.24 / 0.24   0.37 / 0.37    ---- /-----    ---- / ----    ---- / ----    ---- / ----
    19        0.06 / 0.06   0.08 / 0.08   0.12 / 0.11   0.14 / 0.14    0.17 / 0.17    0.20 / 0.21    0.23 / 0.24
    20        0.19 / 0.20   0.23 / 0.22   0.39 / 0.34   0.47 / 0.42    0.55 / 0.50    0.66 / 0.64    0.74 / 0.74
  25-35       0.37 / 0.39   0.47 / 0.46   0.71 / 0.68    ---- / ----    ---- / ----    ---- / ----    ---- / ----
    36        0.21 / 0.21   0.26 / 0.25   0.39 / 0.38   0.48 / 0.43    0.56 / 0.56    0.68 / 0.70    0.77 / 0.80
    37        0.10 / 0.11   0.13 / 0.13   0.20 / 0.19   0.24 / 0.24    0.29 / 0.28    0.36 / 0.35    0.41 / 0.41
    38        0.06 / 0.06   0.07 / 0.07   0.11 / 0.11   0.14 / 0.13    0.16 / 0.16    0.19 / 0.20    0.22 / 0.23


The calibrated parameters compare favourably with those inferred from other morphologically similar
catchments having more highly rated streamgauge data. In this instance, data have been inferred from
previous model calibrations to streamgauge records in Moggill Creek and Bulimba Creek in the outer
suburbs of Brisbane, with a comparison as in Table 12 below:

Table 12 Comparison Of Adopted Operating Parameters With Other Calibrations
   Operating Parameter       Adopted Values          Moggill, Bulimba Creeks
          Alpha                   0.85                     0.80 – 0.83
            m                     0.80                     0.75 – 0.80
         IL (mm)                   16                        15 – 20
        CL (mm/hr)                  2                          2-3


The predicted peak inflow rates to the upstream end of the floodway model also compare favourably to
the peak flow rates in L&T’s Mike 11 floodway model, as in Table 13, below:

Table 13 : Comparison of BSM / CLT Peak Flows (m3/sec) At Upstream Boundaries Of Site
 BSM Subareas  CLT Mike XS        10 Year       20 Year       50 Year      100 Year
 1–5           T3-789             14.4 / 12.1   17.3 / 16.1   21.3 / 21.8  24.8 / 25.7
 12 – 16       T2-457             11.2 / 11.0   13.5 / 13.2   16.5 / 16.5  18.8 / 18.7



5.4     Linkage From Catchment Model To Floodway Model

BSM’s in-house ‘UrbsInt’ and “AsciXP” subroutines were used to convert flow outputs from particular
subareas or groups of subareas within the Urbs model to inflow hydrographs at particular nodes within
the floodway model, as in Table 14, hereafter:




      Brisbane Stormwater Management Pty Ltd Document File: ValkevSDF.Doc                            Page 11