Comparison of conventional stormwater management vs. low impact development techniques for the Upper Thames River Watershed Conservation Centre using PCSWMM

Imtiaz Shah and Yinheng Chen


The new Watershed Conservation Centre (WCC) of the Upper Thames River Conservation Authority (UTRCA) is situated next to Fanshawe Reservoir on the north branch of the Thames River in the City of London, Ontario. It was important to consider the quality of the runoff discharging from the WCC site due to its proximity to the reservoir. Low impact developments (LIDs) and conventional stormwater management (SWM) were the two approaches designed for this site to minimize the effects of stormwater runoff on downstream water quality.

LID techniques can minimize the effects of urban development and alleviate the pressure on a stormwater sewer system. SWM LIDs were used on the site to completely eliminate the use of storm sewers.

PCSWM modeling techniques for various storm events and rainfall duration were used to analyze and compare the performance of the SWM LID techniques used in the two WCC parking lots to the conventional SWM techniques used.

The analysis indicates that the LID techniques have increased infiltration by approximately 64% and, thus, reduced runoff for the various storm events and durations considered in the study. The rate of peak runoff in the pervious parking lot has been reduced by approximately 78% compared with the impervious parking lot. In addition, the PCSWM modelling results shows the time to peak is delayed in the pervious parking lot.

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