Fig. 3. The rainfall distribution within storms A and B marked by stars in Fig. 2.
Each of the hourly 32 storms generated for the baseline period was used as an input to XPSWMM. From there, the runoff accumulated in the detention pond was predicted and the maximum accumulated runoff during the 24-h duration was identified as the critical runoff volume for the storm under consideration. The EPD fitted to the 32 values is shown in Fig. 4(a). A few important and relevant observations can be made regarding the results shown in Fig. 4. The natural weather variability, quantified by the generation of an ensemble weather series and represented in the form of a probability distribution, is a major source of uncertainty around the critical (design) storm. This is evident even with regard to the total storm depth (Fig. 4(b)).