In MSMA (2000), the method of estimating Permissible Site Discharge (PSD) and Site Storage Requirement (SSR) is the Swinburne Method developed at the Swinburne University of Technology in Melbourne, Australia.
The method is basically site-based, but considers the position of a site within the catchment. Refer to Figure 3.2, the peak flow time of concentration from the top of the catchment to the development site, , is compared to the total time of concentration for the catchment, . The PSD varies with this ratio and may be less than or greater than the peak pre-development site discharge depending on the position of the site within the catchment.
The method uses the Rational Method to calculate site flows, and utilizes a non-dimensional triangular site hydrograph based on the triangular design storm method as shown in Figure 3.3. The site discharges are calculated using the total catchment time of concentration tc (not the time of concentration to the development site) for the design storm ARI under consideration as shown in Figure 3.2.
Editor :- Dilah – 13 Feb 14