Ecology & Restoration Information Portal
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Ponds vs Wetlands - Performance Considerations in Stormwater Quality Management
Author/s:
Wong, T.H.F., Breen, P.F., Somes, N.L.G.
Ponds and wetlands are commonly used in urban design to meet a number of urban planning objectives including the management of urban stormwater for water quality improvement. Ponds and wetlands are detention systems with their differences typically being reflected in their surface area to volume ratio and water level fluctuation. These differences influence a number of hydrologic, hydraulic and botanic factors of the detention system, which affect their performance in stormwater treatment. The detention periods of stormwater inflow into these systems are often used as a measure of the performance of these facilities as pollution control systems. However, it is widely recognised that other factors such as the flow hydrodynamics within the detention system and vegetation density and layout can have a significant influence on the performance of these facilities. The appropriate selection of ponds and wetlands for stormwater treatment requires a balance of the advantages and disadvantages of these systems as stormwater quality treatment facilities. This is dependent on the type and priority of pollutants to be removed and the association of these pollutants to the particle size fractions of stormwater sediments. This paper discussed the various issues and performance considerations associated with the comparison of ponds and wetlands for stormwater pollution control.
1999
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Improving Urban Stormwater Quality - From Theory to Implementation
Author/s:
Wong, T.H.F.
Increasingly over recent years, initiatives to protect the aquatic environment of urban areas have been a focus of many federal, state and local government organisations and community groups. Many of these initiatives have successfully reduced point sources such as sewage discharge and industrial effluent. Urban stormwater and its role in conveying pollutants to our urban waterways is now widely recognised as the next major issue to tackle. However, the sources of urban pollutants are diffuse and inherently more difficult to manage.
2000
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Assessment Of Pollutant Removal Performance In A Bio-Filtration System - Preliminary Results
Author/s:
Lloyd, S.D. , Fletcher, T.D. , Wong, T.H.F., Wootton, R. M.
This paper presents the preliminary findings of a series of controlled field experiments investigating the pollutant removal effectiveness of a newly constructed bio-filtration system. A bio-filtration system consists of an infiltration system (e.g. gravel infiltration trench) overlain by a vegetated (normally grass) swale. Flow conditions corresponding to the peak discharges of the 3 month, 1 yr and 5 yr ARI events were simulated. In addition, experiments involving the operation of the swale by itself were undertaken, by discharging flows directly into the swale, with inlets to the underlying infiltration trench blocked. In essence, the system operated as a swale with a relatively high infiltration capacity due to the underlying trench.
Pollutant removal efficiency was investigated by dosing of the system with pollutants of known characteristics and mass. Two pollutant sets were used (differing in mass, to achieve two different concentrations for each flow rate) consisting of Bromide, TSS, PO4, and NOX. Bromide (Br) has been used as a conservative tracer, allowing the mass balance of the pollutographs to be calculated.
The results presented in this paper are for the 3 month ARI simulation (~2.5 l/s) for the full bio-filtration system, and the simulation whereby flows were discharged to the swale component of the system only, at a rate of approximately 2 l/s. The results show TSS removal of between 55% and 74%, and TP removal of between 24% and 55%. The relatively low phosphorus removal may in part be attributed to the exclusive use of soluble reactive phosphorus in the dosing mix. While a reduction in NOX was observed, no effective removal of TN was found.
2001
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A Changing Paradigm In Australian Urban Stormwater Management
Author/s:
Wong, T.F.
Contemporary urban stormwater management is aimed at reducing the impacts of urbanisation on the natural water cycle. Management objectives go beyond the traditional concept of efficient and rapid conveyance of urban stormwater runoff and now include the protection of aquatic ecosystem health of receiving waters, promotion of stormwater as a resource and integration of stormwater management facilities into the urban landscape. By necessity, urban stormwater management now needs to be broadly based, requiring multi-disciplinary inputs. In Australian practice, the adoption of an integrated approach to urban design that implicitly integrates urban stormwater management practices has been slow and sporadic. However, the past three years have seen increased efforts to forge a stronger link between research institutions, state and local government departments and the land development industry. This represents a significant paradigm shift in stormwater management practice in Australia. Research organisations are now placing a higher emphasis on effective engagement and partnership with the industry. Recent land development projects have adopted a Water Sensitive Urban Design philosophy, a reflection of the changing paradigm towards an integrated urban water cycle management approach to ecologically sustainable urban design. In most states of Australia, current institutional arrangements are such that the responsibility for urban water resources management are fragmented and make integrated water management difficult. Efforts are made to overcome this impediment to provide the necessary administrative and regulatory framework to support industry adoption of best practice environmental management of urban stormwater. This paper describes the current status of Australian practice in urban stormwater management and outlines some of the initiatives taken to complete the paradigm shift to an ecologically sustainable urban stormwater management.
2001
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Managing impacts of urbanisation on receiving waters: a decision support framework
Author/s:
Fletcher, T.D., Wong, T.H.F., Duncan, H.P., Coleman J.R. & Jenkins, G.A.
Managing the impacts of urbanisation on receiving waters involves a complex process of investigation, evaluation and prioritisation of proposed strategies. Urban waterway managers have been hindered in this task, by inadequate information about the likely water quality emanating from catchments under various development scenarios. Similarly, managers have had limited ability to predict the performance of stormwater treatment measures, either singularly, or as part of an integrated stormwater management strategy. In an attempt to address these limitations, the CRC for Catchment Hydrology has developed a computer based decision support system called MUSIC (Model for Urban Stormwater Improvement Conceptualisation). MUSIC provides a suite of tools that allow urban waterway managers to formulate and evaluate alternative waterway management strategies. Future refinements to MUSIC will enhance its utility, and ultimately allow for the prediction of ecosystem responses to varying stormwater management strategies.
2001
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