Predicting the Performance of Stormwater Infiltration Systems
(2004 – 2011)
Stormwater infiltration systems reduce the impacts of urbanisation on hydrology by infiltrating stormwater to the soil, reducing the frequency and volume of discharges to urban waterways. The most popular type of system is a sub-surface trench or soakaway.
The modelling of these systems can provide insight into their behaviour and performance. However most models used for design rely on simplifying assumptions and their capacity to represent the complex two-dimensional soil flow processes is uncertain. Infiltration systems are also prone to clogging as they accumulate sediment and while there is considerable concern about this issue existing models have limited capacity to represent clogging processes. The main aim of the research was to develop an integrated model to represent the main storage, soil flow and clogging processes.
The model has been tested using case studies and calibrated to two dimensional laboratory experimental data for both unclogged and clogged conditions. The results have shown that the model is capable of representing the processes that occur within and around a stormwater infiltration system throughout its life cycle as a clogging layer develops.
The model is being applied to a number of different design configurations to gain an understanding of how different shapes may result in different behaviour and also to investigate how well existing models represent the range of systems, particularly infiltration trenches. Modelling of clogging is also being undertaken to better understand the rate at which clogging occurs and its effects on the long term hydrologic effectiveness of systems with different soils and climate patterns. A simple model using a factor to increase lateral flows to mimic the behaviour of the more complex model has been developed and implemented in MUSIC Version 4, making part of the research outcomes available to designers of stormwater infiltration systems.