Natural wetlands optimal for stormwater management

stormwater ponds, constructed wetlands poor replacements

In many areas, stormwater management ponds are continuing to replace natural wetlands. However, University of Waterloo researchers have found constructed ponds may not be sustainable to restoring depleting wetlands or preserving biodiversity.

Led by Waverley Birch, Waterloo researchers examined natural wetland loss, pond creation, land use and land cover trends in seven municipalities within the most populated ecozones in Canada from 2002 to 2010 using a geographic information system.

“Wetland loss contributes to loss of ecosystem services in Ontario, with the likelihood of natural disasters such as droughts and floods becoming more common in urban areas,” said Birch.

Over the eight years under study, findings reveal the total number of constructed ponds was 1.6 times greater than the number of natural wetlands lost for all the municipalities.

This is concerning because of the low proportion of wetlands left in these areas and the fact that the average SWM pond was smaller than the average lost wetland, pos(ing) a big environmental challenge,” Birch said.

Researchers observed that losses are concentrated among wetlands that are generally not protected by provincial policies because of their small size. They “recommend protections strengthened for (natural) wetlands of all sizes, … (which) are vital for biodiversity as well as human health and wellbeing,” added Birch.

Read the published article in the Journal of Environmental Management.