The effectiveness of on-site detention for drainage system in taman halaman indah using stormwater management model (SWMM)
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Date
2019-06
Authors
Yusrina Binti Yusop
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Abstract
The change of land use through the conversion of natural land to urban land
increase the possibility of flood occurrence. This is due to large impervious surface area
after the development and prevent the movement of stormwater to infiltrate naturally into
the ground. On-site detention is introduced as a tool for flood mitigation in this study.
The objective of the study is to model Taman Halaman Indah drainage system using
SWMM, to evaluate the existing drainage system at the study area and to evaluate the
effectiveness of OSD as a drainage system at the study area. On-site detention is designed
to stored stormwater temporarily on site and gradually release a volume of stormwater
runoff to attenuate flow at a controlled rate. The EPA Storm Water Management Model
(SWMM) software is used in this study to simulate the drainage system at the chosen
study area. SWMM is used in planning, analysis and designing detention storage for
urban drainage systems to minimize the effect of urbanization. The chosen study area is
Taman Halaman Indah because there are potential of localise flooding to happen at the
particular area after facing high tide and heavy rainfall. Based on the calculation, the time
of concentration of the study area is 57.04 minutes where the time of overland flow and
drain flow are 33.30 minutes and 23.34 minutes, respectively. Therefore, 1-hour storm
duration is used for design rainfall intensity. By using empirical equation, the rainfall
intensity is 79.03 mm/hr. Based on the results from the analysis, the effectiveness of the
OSD on Taman Halaman Indah exhibits reduction in peak discharge up to 31.33 % from
2.068 m3/s to 1.420 m3/s at the outlet. Besides that, the time taken to conveys the
discharge from study area with OSD is longer than without OSD. This is because the
OSD stores the water temporarily and controlled stormwater flow into the drain by
releasing it gradually through orifice. The location, size of OSD and the design ARI are
the factors that can affect the effectiveness of OSD.