Modelling Sediment Behaviour in Constructed Stormwater Wetlands

(2004 – 2008)
Yong Li

Constructed stormwater wetlands are widely used to improve stormwater quality. Modelling sedimentation of suspended solids in wetlands is essential, since a significant proportion of urban stormwater pollutants are transported in particulate form. Many models have been developed for sediment removal, but reliability, robustness and complexity limit applications.

This study developed a new approach for continuous prediction of trapping efficiency of sediment particles through laboratory, field and modelling studies. More than 80 steady-state experiments were undertaken in four mesocosm wetlands and one non-vegetated pond at the Monash Hydraulics Laboratory, exploring sedimentation factors pertaining to wet and dry weather. Based on analyses, a non-linear regression model was developed for prediction of sediment trapping efficiency in constructed stormwater wetlands. The proposed model is physically based, with key coefficients independent of flow rate and sediment characteristics. Field data from a wetland was used to test laboratory findings. The model was modified with background concentration to account for wash-off and re-suspension of fine particles caused by environmental factors. Together with a common flow-hydrodynamic model (CSTRs model), it handles variable flow conditions in real wetlands. Modelling results were compared with those generated from the widely-used, first-order kinetic decay (k-C*) model and proved better suited to varied flow conditions in constructed stormwater wetlands without complex calibration. Further field studies are required for model verification and future refinements.

Click here to read the abstract of this PhD – PDF (50KB)

Supervisors:
Prof Ana Deletic and Prof Tim Fletcher

Publication:
Li Y. (2008) Modelling Sediment Behaviour in Constructed Stormwater Wetlands. Department of Civil Engineering, Monash University.

Other Publications (link)

Link:
Vegetated Filtration Systems/BiofiltersWSUD Technologies
Implementation Models Program