Evaluation of Stormwater Management Practices for Stream Erosion

Reduction of stream erosion after urbanization is a stormwater management objective in Ontario, Canada. In order to evaluate stream erosion potential after urbanization at a small watershed in northern Ontario, a stormwater management model was developed to simulate the flow-duration relationships without and with stormwater management practices. It was found that flow-duration characteristics could change significantly after urbanization and accelerate stream erosion. Extended detention basins with short detention time (24-hour) could control flow-duration characteristics at low flow rates better than those with long detention time (48-hour). If the watershed were to be urbanized beyond 40% of imperviousness, it may not be possible to bring the flow duration curve back to its original position even though various source control measures and detention basins were used. The optimal location of detention ponds for erosion control is dependent upon the range of flows which control the stability of the stream.