Visualisation of clogging in green infrastructure growing media

Abstract

Growing media in green infrastructure (GI) designed for stormwater management plays a critical role in providing hydrological benefits. However, sediment deposition by urban stormwater can cause clogging and reduce the infiltration capacity. This study introduces a new approach to characterise the impact of clogging of GI that uses fluorescent tracer particles. Results are compared for two contrasting growing media: Grey to Green Substrate (G2G) and Marie Curie Substrate (MCS). Results showed that most sediment particles were retained on the surface of both growing media, and surface clogging in G2G caused a decrease in infiltration capacity. Sediment vertical movement was observed in both growing media, but particles travelled deeper in MCS. Vertical sediment movement is influenced by the growing media’s pore size distribution, and a high clogging risk is expected in growing media with a pore size distribution that is close to the particle size distribution of the incoming sediment particles.