Efficiency of Swale and Dry Pond for Stormwater Management


The implementation of the Best Management Practices (BMPs) in a drainage system through the Stormwater Management Manual For Malaysia or better known as Manual Saliran Mesra Alam (MSMA), focusing on constructed swale and dry pond, was studied. 

The study was carried out on the Bio-Ecological Drainage System (BIOECODS) at Engineering Campus, Universiti Sains Malaysia (USM), Nibong Tebal, Pulau Pinang, located in Kerian River Basin. Besides the implication of the swale and dry pond toward the inflow hydrograph of a series of ponds (detention pond, wetland and recreational pond known as ECOPOND) in managing stormwater quantity in development area, factors that affect the effectiveness of the swale and dry pond using hydrologic and hydraulic model were also identified. 

The collected data such as rainfall, flow, water level, emptying time and infiltration rate from October 2003 until December 2008 at USM were analysed using SWMM 5 model. The simulated hydrographs for swale, dry pond, wetpond, detention pond, wetland and recreational pond were compared with recorded flow at the sites. The modeling shows that the SWMM 5 model has the accuracy up to 30% in simulating the observed hydrographs.

The integrated swale and dry pond as designed for BIOECODS has attenuated the peak flow compared to that of a concrete drain system. The SWMM 5 model shows that there is a reduction of 121.4% in peak flow. Also, the increase in peak flow is expected if several of the existing dry ponds are to be replaced for new development purposes. These results can lead to better understanding of the role of swale and dry pond that suit the Malaysia climate and environment.