Tony Hoong Fatt Wong

The water sensitive city: Principles for practice

With the widespread realisation of the significance of climate change, urban communities are increasingly seeking to ensure resilience to future uncertainties in urban water supplies, yet change seems slow with many cities facing ongoing investment in the conventional approach. This is because transforming cities to more sustainable urban water cities, or to Water Sensitive Cities, requires a major overhaul of the hydro-social contract that underpins conventional approaches. This paper provides an overview of the emerging research and practice focused on system resilience and principles of sustainable urban water management Three key pillars that need to underpin the development and practice of a Water Sensitive City are proposed: (i) access to a diversity of water sources underpinned by a diversity of centralised and decentralised infrastructure; (ii) provision of ecosystem services for the built and natural environment; and (iii) socio-political capital for sustainability and water sensitive behaviours. While there is not one example in the world of a Water Sensitive City, there are cities that lead on distinct and varying attributes of the water sensitive approach and examples from Australia and Singapore are presented.

Water sensitive urban design - the journey thus far

Abstract The paper presents an overview of the current state of adoption of water sensitive urban design (WSUD) in Australian practice and future trends. At the inaugural conference on WSUD in Melbourne 2000, four major inter-related issues were identified as essential elements in underpinning the effective adoption of WSUD. These were (i) Regulatory Framework; (ii) Assessment & Costing; (iii) Technology & Design; and (iv) Community Acceptance. Since 2000, progress in each of these issues has led to further advancement of WSUD in Australian practice. Successes in implementation are however varied, a reflection of an industry transitioning into a new paradigm. The technology and design of WSUD elements have evolved since 2000 with many projects demonstrating innovation at a range of scales. Current trends in concept and systemic design, and recent research findings, are rapidly advancing innovation in this regard. Construction and maintenance practices are identified as one of the recurring impediments to the effective implementation of many excellent conceptual designs ofWSUD. Institutional reform for integrated urban water cycle management remains elusive. The socio-institutional dimension of WSUD, while instrumental to effective policy development and technology diffusion efforts, still remains a largely underdeveloped area of research

A Model for Urban Stormwater Improvement Conceptualisation

Catchment urbanisation leads to increased hydraulic and pollutant loadings into receiving waterbodies. Issues concerning pollution that endangers the sustainable utilisation of water resources have focused government authorities towards integrated catchment management, where both causes and effects of pollution are addressed. Recent research has provided a platform for improving urban stormwater management. The CRC for Catchment Hydrology (CRCCH) has recently developed a Model for Urban Stormwater Improvement Conceptualisation (MUSIC), which serves as a decision support system (DSS) that packages the results of many research activities undertaken at the CRCCH and other organisations into an easily used tool. MUSIC enables urban catchment managers to (a) determine the likely water quality emanating from specific catchments, (b) predict the performance of specific stormwater treatment measures in protecting receiving water quality, (c) design an integrated stormwater management plan for each catchment, and (d) evaluate the success of specific treatment measures, or the entire catchment plan, against a range of water quality standards. This paper describes the operation of the model, the principal algorithms, and research activities undertaken in the CRC directed at further enhancing the system.

Interdisciplinarity: How to catalyse collaboration.

FACT FINDING Interdisciplinarity will be a headline topic at the GRC annual meeting in Delhi in May 2016, organized by India’s Science and Engineering Research Board and RCUK. A report on the state of play worldwide is being commissioned by RCUK, on behalf of the GRC (the team to undertake the research will be appointed in October). The report will survey current policy and practice among global research funders. What forms of support do they offer to interdisciplinary research? How and where is it done? What are its outputs and impacts? The survey will begin to establish base data on how interdisciplinarity can best be stimulated and managed, and look for good practice in this most precious and complex of research endeavours. The GRC expects to issue a policy statement following this meeting, as it has done previously on topical areas. These documents focus and clarify attitudes on key subjects. They marshal data that can be used while national policies are established and international cooperation is developed. We need much better definitions of what kind of thing we are supporting when and if we support interdisciplinary research, and better intelligence about what works. ■

Adaptation of wastewater surface flow wetland formulae for application in constructed stormwater wetlands

Abstract Over the past 30 years, the use of constructed wetlands for wastewater treatment has been a topic of significant research culminating in a good data base from which simplistic equations have been derived to aid in the design of these facilities to meet long term water quality treatment performance criteria. Over the past decade, the use of treatment wetlands has extended to stormwater and combined sewer overflow (CSO) management applications. Designing constructed wetlands for stormwater and CSO applications have unique challenges stemming from the highly stochastic nature of the hydraulic and pollutant loading on a stormwater wetland compared with wastewater treatment systems. This paper explores the possibility of adapting the simplistic models for wastewater wetlands for interim use in developing design guidelines for stormwater wetland systems. A procedure that takes into account the unsteady intermittent nature of stormwater inflows to these wetlands has been incorporated into one of these simplistic models and a case study presented to demonstrate the application of the procedure.

Numerical simulation of wetland hydrodynamics

Abstract This paper describes the numerical simulation of flow hydrodynamics within a wetland. Using data collected from a field-based investigation of wetland hydrodynamics in the Monash University Research Wetland, a two-dimensional model was developed and calibrated. MIKE 21, a two-dimensional depth averaged model developed by the Danish Hydraulic Institute was used to undertake the simulations. Field observation found that hydraulic roughness, as reflected in the different zones of vegetation, and the relationship between water depth and vegetation, were the factors that controlled flow within the wetland. However, calibration of the model found eddy viscosity was the key calibration parameter due to the flow within the wetland being dominated by inertia rather than friction.

A stochastic approach to designing wetlands for stormwater pollution control

Central to wetland design for stormwater pollution management is the proper control of the hydrologic regime of these wetlands and wet detention basins. The paper proposes a stochastic approach in determining the appropriate wetland size for stormwater treatment in recognition of the inherent variability of stormwater runoff and pollutant load generation within a storm event and between storm event. The determination of wetland size would include the use of stochastic generation of stormwater runoff and continuous wetland behaviour simulation. A typical design chart summarising the interaction between wetland size, prescribed retention period of stormwater and wetland hydrologic effectiveness for Melbourne is presented. The chart enables the selection of the appropriate storage volume and outlet characteristics on the basis of long-term average effectiveness of the wetland to retain stormwater over a desired minimum period rather than a prescribed level of performance for an individual probablistic event.

Sediment Characteristics in Stormwater Pollution Control Ponds

Summary Wetlands systems are often monitored to assess their performance during a flow through event. The spatial mapping of sediment deposition within pollution control ponds complements water quality data, providing information on the efficiency and sustainability of the system as a pollution abatement facility. The characterisation of the sediments and associated pollutants allows a better understanding of the role of sedimentation in the overall improvements to water quality. In stormwater systems, the efficiency with which pollutants such as TSS and pre-dominantly sediment-bound contaminants such as phosphorus, metals and polycyclic aromatic hydrocarbons are removed is intrinsically related to the characteristics of the sediment inflow to the wetland. The sediment-bound pollutants are known to have a higher association with the finer range of sediment sizes and targeting the removal of the appropriate particle size fraction is necessary in designing stormwater pollutant abatement facilities. This paper presents the results for two studies of sediment characteristics: the first is at the Monash University Research Wetland in Australia and the second at the Braunebach Wetland pollution abatement facility in Germany. Sediment cores were taken at regular grid intervals to identify the physical characteristics of the accumulated sediments in these wetland systems. Defining the spatial sediment deposition patterns and the associated particle size distribution provided a greater understanding of each system’s water quality improvement function. This understanding of sediment characteristics has direct implications for the management of pollution control facilities and enables modifications to be suggested for future designs.

Size distribution and partitioning of urban pollutants

This paper reports the results from a study carried out to characterise the dry sediments and road surfaces and gutters in several parts of Melbourne. The particle size distribution of the sediments determined as well as the nutrient and heavy metal concentrations in the various particle size ranges. The dry solid samples are also subjected to chemical analysis to fractionate soluble, mobilisable and particulate residual contents for nutrients and metals across different particle size ranges. The objective of this study is to provide an indication of the potential loading and pollutant characteristics in urban stormwater from different geologic types in Melbourne. It is part of a larger study, which investigates the size and distribution of particulate pollutants actually transported in urban runoff from different geological conditions to develop relationships and pollutant load characteristic curves to assist in the design of stormwater improvement facilities.

Designing outlet characteristics for optimal wetland performance

Central to the hydrological and botanical design of constructed wetlands for stormwater quality management is the proper control of their hydrologic regime. The hydrologic regime, defined as the probabilistic distribution of inundation depth in the wetland, reflects the inherent variability of storm inflows to the wetland and is directly influenced by the discharge characteristics of the outlet structure of the wetland. The influence of three typical outlet structures on the hydrologic regime of a hypothetical wetland was investigated using a continuous simulation approach. The three outlet types investigated were that of a culvert, a riser and a siphon. Simulations found that all three devices provides equally effective control of the ability of the wetland to capture and detain storm runoff but can have different influence on the hydrologic regime of the wetland. The siphon-controlled wetland was found to exhibit a more even distribution of inundation depth compared to the other two outlet types.