307 - Linking Storm Type and Sediment Transport within GSI

Green Stormwater Infrastructure (GSI) are open systems, taking in stormwater and sediments from the local environment. Understanding this balance is critical to the maintenance and sustainable function of these systems. Deposition of fine sediments at the surface of the GSI can affect long-term performance as infiltration decreases due to clogging, while erosion of GSI media, associated with high shear stress flows, can expose or undermine areas and add to the transport of material through the GSI. The degree and style of sediment transport varies by storm event. Sediment transport within the GSI is a function of the volume and flow shear stress of each storm event. Storm events resulting in flows with high shear stress, not necessarily the greatest volume, cause sediment transport that requires maintenance action. This study investigates the linkage between storm event types and sediment transport, described by the spatial distribution of erosion and deposition and the particle size distribution of deposits. This investigation uses a 2D HEC-RAS sediment transport model of a bioinfiltration trench to test sediment transport during a range of storms. Surficial sediment sampling activities have been carried out in the study areas, and the particle size distribution information collected is compared to the simulated results from the HEC-RAS model. Ultimately, understanding the linkages between storm event type and sediment transport will aid in defining maintenance triggering events for GSI.