Understanding urban subsurface flow pathways from stormwater infiltration
Project Leader: Meenakshi Arora
Staff: Tim Fletcher, Meenakshi Arora, Andrew Western, Stephan Matthai
Primary Contact: Tim Fletcher (firstname.lastname@example.org)
Keywords: contaminant transport; porous media; saturated-unsaturated flow
Disciplines: Infrastructure Engineering
Domains: Optimisation of resources and infrastructure
Stormwater infiltration basins are among the most widely applied stormwater control measures worldwide, in part for their ability to intercept stormwater runoff and allow it to infiltrate into the ground, with the assumption that this will recharge groundwater and help restore clean, filtered baseflows to urban streams. Stormwater infiltration basins provide substantial localised (point-source) additions to the subsurface water store, with the potential to generate major contributions to groundwater and/or lateral seepage to streams.
There is increasing concern however, that infiltration basins may, in some situations, fail to restore stream baseflows (in terms of both flow regime and water quality), due to the gross disturbance of subsurface flow paths caused by urban underground infrastructure (e.g. water, sewer and gas pipes, communications conduits) and their associated gravel-filled trenches (collectively referred to as the ‘urban karst’). These highly-permeable trenches potentially lead to ‘short-circuits’ that could rapidly transmit water and pollutants to streams, undermining the objectives of infiltration systems. Therefore, it is important to understand the potential for infiltrated stormwater to mobilise pollutants in urban soils and subsurface flows to surface waters such as streams.
This PhD project aims to understand the fate and pathways of infiltrated urban stormwater and associated pollutants, and the implications for the flow regime and water quality of urban streams, by developing a very detailed physically based model of a selected site. The student will develop advanced subsurface flow and transport simulations to represent both the field study site and a range of typical generalised situations. This will contribute to a better understanding of the spatial design of infiltration systems (i.e. improved siting of such facilities). The ideal PhD candidate will enjoy numerical analysis and problems, have experience with CAD, an understanding of groundwater hydrology and transport simulation as well as some programming or data analysis experience.