Quantifying the environmental benefits of wetland restoration

Researchers have developed a model that could make the job of restoration planners much easier. Wanhong Yang and fellow scientists created and tested a prototype for quantifying the amount that prospective restoration projects would reduce flooding and retain sediment and nutrients. This model can serve as a tool for decision makers to calculate and compare the environmental benefits to watersheds from different wetland restoration scenarios.

They created the model by modifying a commonly used hydrologic assessment tool applied to watersheds. They took the Soil and Water Assessment Tool (SWAT) and added in their own component, which takes into account wetland function. They applied a prototype of their tool to evaluate the effects of six different simulated wetland restoration scenarios in the 25,139 ha Broughton’s Creek watershed in western Manitoba.

Since 1968, the wetland acreage of the prairie watershed has decreased from 2998 to 2379 hectares. Based on their modified SWAT model they found that restoring the wetland acreage back to 1968 levels would reduce the peak discharge by 23.4% and the average loading sediment by 16.9% at the watershed outlet.

According to their analysis, this restoration scenario would also reduce total phosphorus and nitrogen loadings by 23.4% (interesting that this is the same amount as the reduction in peak discharge but this seems to just be a coincidence). The study authors were also able to determine which restoration scenario would be most efficient in terms of reducing peak flow and sediment. They found that restoring 50-80% would give the greatest ratio of environmental benefit to wetland area.

This modeling tool obviously could be very useful to those contemplating watershed-scale wetland restoration planning. For those interested, the study provides an in-depth methodology on its development and use.


--Reviewed by Rob Goldstein

Yang, W., Wang, X., Liu, Y., Gabor, S., Boychuk, L., & Badiou, P. (2009). Simulated environmental effects of wetland restoration scenarios in a typical Canadian prairie watershed Wetlands Ecology and Management DOI: 10.1007/s11273-009-9168-0