Australian Research Council (ARC) Discovery Early Career Researcher Award (DECRA) Fellow, affiliated with Monash University
Current Chair of the International Water Association (IWA) Working Group on Modelling Integrated Urban Water Systems (MIUWS)
Member of the Management Committee of the International Water Association (IWA) Specialist Group on Modelling and Integrated Assessment (MIA)
Managing Editor for the IWA Journal Blue Green Systems
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Wings is an inter- and transdisciplinary strategic research program that strives to develop novel non-grid-connected water and sanitation systems that can function as comparable alternatives to network-based systems.
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Modelling characteristics of the urban form to support water systems planning
A spatial model is presented, based on urban planning concepts for abstracting urban form characteristics in new and existing areas. Requiring input maps of land use, elevation, population and parameters from planning regulations, the model conceptualises (on a spatial grid) attributes including impervious fraction, allotment geometry and roof areas among other relevant characteristics for integrated urban water management. The model is calibrated to three different Melbourne districts, varying in size (10–60 km2) and land use. Performance was evaluated by comparing modelled outputs with observations of total dwelling count, employment and spatial distribution of impervious fraction and residential roof areas. Results not only highlight reasonably good prediction, particularly with spatially variable indicators such as imperviousness across all case studies, but also logical contrasts and consistency in the chosen planning parameters across the different case study districts. Discrepancies highlight aspects needing improvement and potential for exploring auto-calibration and model sensitivity.
Use and utility: exploring the diversity and design of water models at the science-policy interface
Effort to narrow the gap between the production and use of scientific knowledge for environmental decision-making is gaining traction, yet in practice, supply and demand remains largely unbalanced. A qualitative study based on empirical analysis offers a novel approach to exploring key factors, focussing on seven water models in the context of two organisations at the science-policy interface: the PIREN-Seine in France and the CRC for Water Sensitive Cities in Australia. Tentative linkages drawn from these examples identify: (1) objective and expertise; (2) knowledge and tools; and (3) support structures as main drivers influencing the production of scientific knowledge which, in turn, affect the use and utility of modelling tools. Further insight is gained by highlighting the wide spectrum of uses and utilities existing in practice, suggesting that such 'boundary organisations' facilitate interactions and exchanges that give added value to scientific knowledge. Coordinated strategies that integrate inter-, extra-, and intra-boundary activities, framed through collaborative scenario building and the use of interactive modelling platforms, may offer ways to enhance the use and utility of scientific knowledge (and its tools) to better support water resources management, policy and planning decisions, thus promoting a more cohesive relationship between science and policy.
Chong, N.; Bach, P. M.; Moilleron, R.; Bonhomme, C.; Deroubaix, J.-F. (2017) Use and utility: exploring the diversity and design of water models at the science-policy interface, Water, 9(12), 983 (28 pp.), doi:10.3390/w9120983, Institutional Repository
Integrated modelling of stormwater treatment systems uptake
Nature-based solutions provide a variety of benefits in growing cities, ranging from stormwater treatment to amenity provision such as aesthetics. However, the decision-making process involved in the installation of such green infrastructure is not straightforward, as much uncertainty around the location, size, costs and benefits impedes systematic decision-making. We developed a model to simulate decision rules used by local municipalities to install nature-based stormwater treatment systems, namely constructed wetlands, ponds/basins and raingardens. The model was used to test twenty-four scenarios of policy-making, by combining four asset selection, two location selection and three budget constraint decision rules. Based on the case study of a local municipality in Metropolitan Melbourne, Australia, the modelled uptake of stormwater treatment systems was compared with attributes of real-world systems for the simulation period. Results show that the actual budgeted funding is not reliable to predict systems’ uptake and that policy-makers are more likely to plan expenditures based on installation costs. The model was able to replicate the cumulative treatment capacity and the location of systems. As such, it offers a novel approach to investigate the impact of using different decision rules to provide environmental services considering biophysical and economic factors.
A rapid urban flood inundation and damage assessment model
Urban pluvial flooding is a global challenge that is frequently caused by the lack of available infiltration, retention and drainage capacity in cities. This paper presents RUFIDAM, an urban pluvial flood model, developed using GIS technology with the intention of rapidly estimating flood extent, depth and its associated damage. RUFIDAM integrates a 1D hydraulic drainage network model (SWMM or MOUSE) with an adapted version of rapid flood inundation models. One-metre resolution topographic data was used to identify depressions in an urban catchment. Volume-elevation relationships and minimum elevation between adjacent depressions were determined. Mass balance considerations were then used to simulate movement of water between depressions. Surcharge volumes from the 1D drainage network model were fed statically into the rapid inundation model. The model was tested on three urban catchments located in southeast Melbourne. Results of flood depth, extent and damage costs were compared to those produced using MIKE FLOOD; a well-known 1D-2D hydrodynamic model. Results showed that RUFIDAM can predict flood extent and accumulated damage cost with acceptable accuracy. Although some variations in the simulated location of flooding were observed, simulation time was reduced by two orders of magnitude compared to MIKE FLOOD. As such, RUFIDAM is suitable for large-scale flood studies and risk-based approaches that rely on a large number of simulations.
Building effective planning support systems for green urban water infrastructure – practitioners' perceptions
The multiple benefits of adopting distributed, green stormwater technologies in the local environment are increasingly recognised, particularly in relation to water quality, flood mitigation, amenity and aesthetics. To advance the integration of these systems into everyday decision-making practices, Planning Support Systems (PSS) are considered vital. Despite several PSS available to support planners and key decision-makers, their uptake remains constrained; a phenomenon known as the 'implementation gap'. While scholars have hypothesised why the adoption of PSS is limited, there remains little empirical investigation regarding the reasons why. This paper tests the hypotheses underlying the implementation gap in relation to water sensitive urban design (WSUD) planning. Drawing on the tacit experience of 24 key urban water planning professionals in the front-runner city of Melbourne, Australia, in-depth semi-structured interviews were undertaken to unpack the contemporary planning processes used and reveal characteristics leading to success and failure of PSS application. Data analysis revealed WSUD planning professionals regard the adoption of PSS as a significant step towards improving contemporary decision-making practices, which are regarded as opportunistic rather than strategic. PSS use was widespread, though the type, intensity and sophistication of use varied among interview participants. Confirming the hypotheses from planning literature, practitioners suggested PSS need to be user-friendly and align closely to planning practice. Additionally, however, it was found that it is crucial for PSS to meet industry conventions. Suggested improvements to current PSS included incorporating socio-economic factors alongside biophysical and planning factors, hence the role for GIS-based suitability analysis tools. Overall, this study provides current and future PSS-developers with critical insights regarding the type, function and characteristics of an 'ideal' PSS aimed at enhancing the usefulness and uptake of PSS, and thus improve planning that supports expediting green infrastructure implementation.
Evaluating the reliability of stormwater treatment systems under various future climate conditions
Water Sensitive Urban Design (WSUD) stormwater systems, also known as Low Impact Development (LID) systems or Nature Based Solutions (NBS), are currently implemented based on the underlying assumption of statistical stationarity of rainfall, which threatens to become outdated under climatic uncertainty. This paper applies a new downscaling method to examine the implications of climate change on future rainfall and evaluate the reliability of WSUD stormwater infrastructure in pollution reduction, flow frequency mitigation and reliability as an alternative water supply. A variety of future atmospheric scenarios are considered as part of this comprehensive assessment by analysing an ensemble of eight different downscaled General Circulation Models (GCMs). High resolution catchment-scale rainfall projections for Melbourne, Australia were generated using a scheme called High-resolution Downscaling of Rainfall Using STEPS (HiDRUS) at a fine 1 km and 6-min scale for more precise analysis with uncertainty estimates. Statistical analyses show that, in general, the climate models predict a drier future with fewer rainfall events and longer dry periods when comparing the simulated near future (2040–2049) periods against the base-line period (1995–2004). The difference simulated between historical and future rainfall projections show minimum difference of WSUD performance in pollution removal and flow frequency reduction, with slightly lower harvesting reliability ( < 3%) observed under future climate; high variabilities, however, were observed across GCM simulations, indicating big uncertainties of system reliability under various conditions, e.g. design wetland sizes may vary from 2.5% to 4.0% of the impervious catchment area according to different future projects across GCMs. Larger WSUD systems are recommended to ensure reliable performance of pollution removal, as well as harvesting reliability under simulated future conditions. The significance of considering an ensemble of different GCMs as opposed to many scenarios generated by a single 'best' climate model was also demonstrated for the robust estimation of uncertainty in future WSUD reliability. This work highlights important considerations for the future design, management and quantitative evaluation of WSUD reliability.