Abstract

Abstract Inappropriate urban flood management may cause deterioration of urban living quality, known as urban decay. In order to avoid this, the sensitivity of surface runoff parameters towards peak discharge (Q p ) and flood volume (V f ) needs to be analysed. By conducting sensitivity analysis, the influence of any runoff parameter to these two output can be assessed quantitatively. This study aims to sort out the sensitivity of seven runoff parameters towards Q p and V f at part of the suburb of Mawson Lakes, South Australia. Four synthetic rainfall events with the Annual Recurrence Interval (ARI) of 2-year and 50-year; each with the duration of 12 hour and 72-hour; were generated by the AusIFD software. The hourly intensity values of these synthetic rainfall were then fed into the Storm Water Management Model (SWMM) to predict Q p and V f . Further, the initial values of runoff parameters based on previous studies were used in the first flood estimation. Different sets of parameters which were 25% less than and greater than the initial values were used in the next flood modelling. Results showed that the most sensitive parameters were %-impervious followed by Manning’s n-pervious. Modelling using initial values of parameters produced Q p and V f of 0.340 m 3 /s and 2.372 MCM for 2-year ARI respectively, whereas the corresponding values for 50-year ARI were 0.519 m 3 /s and 3.424 MCM, respectively. Decreasing the parameter initial values by 25% produced. Meanwhile, increasing the parameters’ initial value by 25%.

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