Site Based Stormwater Management Plan

4.3    Pre-Development Hydrology

Pre-development peak stormwater discharge was estimated using XPSTORM modelling
software, and compared against the results from the Rational Method. Table 4.2 presents
the comparison to validate the peak flows estimated using XPSTORM.


                                   Peak Discharge Comparison (m3/sec)
   Design Storm         Rational Method              XPSTORM                Difference   % Change
       (AEP)

       63%                    0.089                    0.088                 -0.001        -1%
       39%                    0.114                    0.118                  0.004        4%
       18%                    0.158                    0.163                  0.005        3%
       10%                    0.198                    0.191                 -0.007        -4%
        5%                    0.236                    0.221                 -0.015        -6%
        2%                    0.301                    0.275                 -0.026        -9%
        1%                    0.346                    0.306                 -0.040       -12%
                            Table 4.2 Pre-Development Stormwater Flow Validation



From Table 4.2 the Rational Method results compare well with the XPSTORM model results
for estimates of the pre-developed peak stormwater discharging from the site.


To ensure a robust stormwater detention design the Rational Method results will be used to
represent the pre-developed peak stormwater discharge from the site.




Site Based Stormwater Management Plan                                                    Page 5 of 19
2123-SBSMP-01_Version 1.0 (October 2021)