59 / 2025-04-24 12:55:25

Erosion Mitigation Through Geomorphological Approaches: Integrating Erosion Thresholds and Indices in Stormwater Management

This paper explores the evolution of stormwater management approaches to mitigate erosion, focusing on geomorphologically informed practices and integrating erosion thresholds and appropriate indices. Traditional stormwater management strategies, which emphasized peak flow control through detention ponds, were inadequate to address erosion caused by smaller, more frequent storm events. In jurisdictions like Southern Ontario, frequent low-intensity flows have been identified as primary drivers of channel instability, with many streams exhibiting erosion thresholds far below the two-year return event. This highlights the critical need for site-specific, data-driven approaches.

The integration of reach-scale geomorphic assessments, detailed geomorphological surveys and the application of post- to pre-development scenarios tested with erosion indices, such as the Cumulative Effective Work Index (Wi) and Cumulative Stream Power (ω), provide robust process and tool for understanding and mitigating erosion.

This study examines the application of geomorphological protocols and continuous hydrological modeling in urbanized watersheds, emphasizing their effectiveness in reducing erosion by targeting the full range of flow events. Through several modelling examples, this paper underscores the importance of adapting stormwater management to local channel sensitivities and implementing erosion thresholds in stormwater management designs to ensure long-term stream stability and health.