2018•Swinburne figshare (Swinburne University of Technology)Requires access
A computer tool for designing onsite detention (OSD) based on new Australian Rainfall and Runoff
Iqbal Hossain, Monzur Alam Imteaz
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Abstract
A computer tool was developed to facilitate onsite detention (OSD) design based on recently introduced Australian Rainfall and Runoff (ARR) 2016 design rainfall and procedure. In a primary window the user needs to provide pervious and impervious areas along with their coefficients of imperviousness for a particular catchment. From drop-down menus, user then needs to select design rainfall event and duration of rainfall from recently changed standard design rainfall and durations for Australia. Tool reads design rainfall and temporal pattern from pre-populated spreadsheets, which are linked with the tool. As new ARR recommends, the tool calculates runoff generated for the selected particular rainfall depth/intensity for ten ensemble rainfall temporal patterns. Tool calculates OSD storage required from the calculated runoff time-series (for a particular time period) and user-provided permissible site discharge (PSD). The tool calculates maximum storage required considering worst temporal pattern of rainfall for a conservative design. It also calculates average storage volume required taking averages of calculated storages based on all the temporal patterns. Eventually, for a selected water height, tool calculates required orifice diameter to maintain a given PSD. As a case study, a hypothetical catchment was considered and the tool was used to calculate several storage requirements for various design rainfall with different durations. The tool calculated storage requirements were compared with the widely used urban drainage model, DRAINS. For all the selected scenarios, the DRAINS simulated storage-depth curves show that at the end of any particular selected time period, the OSD systems’ storage height situation is just before overtopping/overflowing, revealing the fact that the developed tools calculated results are compatible with DRAINS calculations under same scenario. Developed tool can be further modified to comply with individual authority’s requirement.