The hydrologic, water quality and flow regime performance of a bioretention basin in Melbourne, Australia

ABSTRACT

To restore streams degraded by urbanisation, bioretention basins (‘raingardens’) are implemented worldwide to reduce stormwater volumes, peaks flows and pollutant loads entering streams. While they are effective at this, their ability to mimic natural flow regimes has received limited field investigation. We monitored the hydrology and water quality of a bioretention basin during a three-year period. We found that the basin reduced the delivery of polluted water to the stream (55–65% of catchment runoff released as treated outflow), with peak flows and event concentrations of TSS, TP and TN substantially lowered too. A smaller proportion of catchment runoff infiltrated into the surrounding soil, but the flow regime delivered by the basin to the local stream was not similar to nearby forested streams. Such systems can mitigate the impacts of urban runoff on streams and shift the urban water balance towards natural conditions, but complete flow regime restoration requires catchment-scale action.

KEYWORDS:

• Bioretention
• stormwater
• urban streams
• WSUD
• LID
• flow regime

Acknowledgements

This work is supported by Melbourne Water and Knox City Council. Prof. Tim Fletcher was supported during part of this work by the Australian Research Council’s Future Fellowship scheme (FT100100144) and the work is supported indirectly by ARC Linkage Project (LP130100295). We thank anonymous reviewers who have contributed greatly to improve this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplementary data for this article can be accessed here.

Additional information

Funding

This work was supported by the Australian Research Council [LP130100295]; Melbourne Water; Knox City Council.