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UrbanBEATS: a virtual urban water system tool for exploring strategic planning scenarios
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posted on 23.01.2017by Bach, Peter Marcus
Models for Water Sensitive Urban Design (WSUD) have been growing in the past decade to encompass more interdisciplinary elements and consider not only traditional engineering design and system performance, but also embrace social, environment and economic issues and harness the capabilities of geographic information systems (GIS). Current WSUD models, however, lack the capabilities to interrelate urban planning, urban design and water infrastructure. The consideration of integration aspects between stormwater treatment infrastructure and the urban environment (which is core to the WSUD ethos) in existing models is highly simplified.
This thesis aimed to develop an integrated model, a virtual urban water system tool known as the Urban Biophysical Environments And Technologies Simulator (UrbanBEATS). UrbanBEATS can model the interaction between urban planning and WSUD to provide users and broader project stakeholders decision-support in the planning process. The model enables users to explore a large number of urban planning, social and policy scenarios, enable more strategic decision-making and promote participatory modelling. The research on UrbanBEATS was framed around four key areas: (i) understanding the interactions between urban planning, society and water infrastructure, (ii) representing the urban form in a conceptual, yet adequate manner for WSUD planning, (iii) modelling WSUD planning for greenfield developments and (iv) modelling WSUD planning for dynamic cities.
Preliminary modelling of the interactions between residential urban form, societal preferences and lot-scale WSUD was conducted on a semi-hypothetical Melbourne case study. The study identified key interactions between statutory planning regulations, which define form and function of urban space, and opportunities for implementing lot-scale infiltration systems. Outcomes of this study and extensive review of the planning-support systems and WSUD modelling literature provided the basis for defining model requirements and defining an overarching model structure. Requirements included the need for interdisciplinary modelling (to address a variety of user groups), focus on and integration of planning problems and model transparency.
UrbanBEATS is a spatial model, which uses a grid representation of the urban environment. Each cell in the grid, known as a ‘block’, is a database of information for that particular urban region. The general model structure comprises two key modules: (a) Urban Planning Module and (b) WSUD Planning Module. The former processes geographic input maps of land use (using its own developed classification system of 13 categories), population, elevation and soil (and other optional maps), creates the grid representation with spatial relationships between the blocks (i.e. neighbourhoods and drainage flow paths) and determines the urban form for each block (using a collection of statutory regulations, census data, and rule-based algorithms). The WSUD Planning Module conducts rigorous design and placement of WSUD stormwater technologies for a number of objectives (runoff, pollution reduction and stormwater harvesting) at a multitude of scales (lot, street, neighbourhood, sub-catchment). Using urban form data, conceptual design, a Monte Carlo procedure and multi-criteria assessment (MCA), the model generates thousands of possible WSUD options to meet water management targets for a required ‘service’ (i.e. spatial coverage of runoff/pollution treatment or amount of water demand substitution). Outputs of the model include maps of urban form data and top-ranking WSUD layouts and are useful for facilitating further discussion among stakeholders.
A water-centric classification of land use within the Urban Planning Module was developed and applied to Greater Metropolitan Melbourne. Analysis showed that the new classification could be derived from existing zoning information available from the local planning scheme. Further analysis of the spatial data reiterated shortcomings of using simple raster-based representations. Abstraction of urban form was tested against real data. The module was calibrated to a large urban metropolitan area within Melbourne against three urban form indicators: impervious fraction, total dwelling count and residential roof area. Results showed that the model satisfactorily reproduced these with several cases of over-estimations.
Initial algorithms for WSUD planning were on the Scotchman’s Ck catchment, a small suburban catchment in Melbourne’s south-east. The study demonstrated how WSUD technological opportunities can be identified and introduced the Utilisation metric as a means for quantifying and analysing large amounts of model outputs in a collective manner. The refined WSUD Planning Module was tested on the Toolern Precinct greenfield development. It was calibrated to reproduce a WSUD layout based on an integrated urban water management (IUWM) plan designed by an external consultant. Results showed similarities with proposed designs, but full validation could not be conducted due to significant data limitations in the study. Scenario exploration was also conducted to assess alternative water management strategies for the precinct including on-site stormwater harvesting. Outcomes showed possible interactions between different spatial scales and technology types to achieve multiple objectives. Dynamic WSUD Planning algorithms (i.e. ‘retrofit’ and ‘implementation’ of WSUD through time) were tested on a historical case study of Scotchman’s Ck catchment using data from urban and social modelling (which were conducted in parallel as part of a broader research project) as input. Preliminary results showed that UrbanBEATS can reproduce adoption patterns of different technologies despite discrepancies in the absolute values.
UrbanBEATS was shown to be highly flexible, usable as a standalone tool for rapid assessment and planning-support to its users, but also integrated into larger complex modelling frameworks. Different simulation modes allow for rigorous assessment of urban environments in a wide variety of ways to address the needs of its user groups. Analysis of model performance throughout the research has provided practical recommendations for its refinement and testing in a planning-support setting. This thesis is by publication and entails six journal papers of which three have already been published.