An analysis of stormwater runoff rehabilitation for integrated BIOECODS using EPA-SWMM

Urbanization that is becoming a trend around the globe, including in Malaysia, has led to an increase in impervious areas. This, in turn, has led to severe flood events in most countries. To alleviate the problem, management actions are required to produce the desired result in flow mitigation. Software and modelling tools can offer support in the specific selection of suitable options. This paper shall focus on a study that was conducted at the academic complex of Universiti Teknologi PETRONAS (UTP). The chosen study location was known to experience flooding as the surface runoff did not drain efficiently on rainy days. An integrated BIOECODS was designed in front of Block 13 and Block 14 of the academic complex using EPA-Storm Water Management Model (SWMM). The existing drainage system was simulated using a model to identify the potential flash flood area. A new diversion flow was then designed to allow surface runoff to discharge into artificial lakes acting as temporary storage before the water flows out through the outlet. The interconnection of the drainage network and artificial lakes in UTP was also analysed in this project. For the simulation model input parameters, rainfall of 50-year ARI with a 30-minute duration was assumed as rain intensity. The hyetograph was converted to input time-series data during model development. The analysis showed that node RS12-274 and node RS113-275 exceeded the maximum depth of surface runoff during storm events. Additionally, hotspot flooding area was determined at a lower elevation level of the roadside drain. Hence, mitigation was proposed by realigning the drain slope and providing a new diversion flow channel. The new model analysed using EPA-SWMM, including the bioretention pond, showed that overflow issues would no longer occur. A recommendation could be proposed when using the simulation model, such as considering some modifications to the EPA-SWMM to adopt best management practices (BMPs) in Malaysia.