Modelling sedimentation processes in a constructed stormwater wetland

The design and operation of constructed wetlands for the treatment of storm water relies heavily on promoting sedimentation, and being able to predict accurately-the expected effectiveness of the pond in removing material from the inflows. A study of sediment behaviour has been carried out in a storm water wetland in Adelaide, Australia where computer predictions, based on s olving the hydrodynamic equations and the transport equation, have been com pared to deposition patterns observed in the field. The long-term residence time distribution has been shown to be useful in predicting overall sedime nt removal rates. Comparisons between the model and field observations indi cate generally good agreement. Sources of potential error identified includ e the variable nature of the runoff concentrations entering the pond and th e sediment size distribution. The importance of the transient nature of the flow events was highlighted by the spread of sediment throughout the whole pond. (C) 2001 Elsevier Science B.V. All rights reserved.