A spatially explicit decision support system to adapt existing parks for the sustainable development of an established urban catchment.

Date

2014

Authors

Raja Segaran, Ramesh

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Lewis, Megan Mary
Ostendorf, Bertram Franz
Hatton MacDonald, Darla

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Abstract

Growing demands for sustainable development call for multidisciplinary approaches to integrate disparate bodies of knowledge and management agendas. In urban environments there is an urgent need to change how resources are managed. Fortunately, they provide unique opportunities to develop integrative solutions to complex issues in a holistic way. The concentrated interactions of social, economic and environmental activity within the 21st century city have generated significant scientific knowledge and vast collections of data which can be used to help develop solutions to balance the complex issues. But novel approaches are needed to efficiently, creatively and adaptively manage the way urban spaces are used. Elements of the urban landscape have traditionally been designed with a single purpose in mind. Public open spaces (POS) are an excellent example of this and of the potential to move beyond the established mindset by integrating multiple functions into single spaces. Recent integrative approaches to achieving multiple POS objectives have focused on planning for new developments, or on providing additional parks in established urban areas. Little work has been done to assess the current function and configuration of existing POS. Increasing the multifuntionality of urban parks to improve the sustainability of urban landscapes may cement their importance, alleviating the pressures their provision currently faces. This research aimed to develop a method to assess multiple functions of existing POS of the urbanised Brownhill-Keswick catchment in Metropolitan Adelaide, South Australia. A decision support system was developed to integrate and assessing the social, economic and biophysical functions of POS with respect to their geographic configurations at multiple scales. The goals of this study were to [1] assess the current social functions of the existing POS system; [2] identify the potential to harness the intrinsic value of their current distribution to enhance their biophysical functionality; and [3] explore the utility of various levels of aggregation of that information. Empirical models were developed of the current functions of POS as spaces for recreational and aesthetic amenity in the study area. Two further models were developed to assess the potential to extend the current functions of the same spaces to improve urban stormwater quality and ecological health. The four models were integrated to describe the performance of the parks as a function of their location within the landscape and relative to one another. Qualitative and quantitative analyses were employed to gain insights into the current distribution of POS and the potential to enhance their role as vital components of a healthy social, economic and environmental urban landscape. The POS were categorised using a set of criteria based on size, facilities and vegetation within the park boundaries into Pocket, Family, Activity and Conservation parks. The recreational amenity of POS was characterised using a randomised on-site survey of users in 50 survey events. A novel survey instrument was used to objectively determine the distances POS visitors had travelled to 25 different spaces in and around the study area. The survey data was used to model the decrease of visitations with increasing distance from the four different POS types. A hedonic price model was used to quantify the aesthetic value of the urban forest and to attribute POS with the value they contribute to their immediate neighbourhoods. Property sales data on 2,497 unique single family residences in the study area were used to regress sales price against structural, temporal and geographic variables. The geographic variables included distance to the nearest park and neighbourhood greenness; a measure of vegetation within a 100 metre radius. Each additional percentage point of neighbourhood greenness was estimated to contribute $1,890 to real estate value, holding all other variables constant. POS were attributed with the financial value that they contributed to the aesthetic character of the land surrounding them. Their aesthetic appeal was estimated as providing up to $9 million value, with all POS assessed as contributing $146 million dollars to real estate prices. The capacity of POS for added functionality to improve stormwater quality with bioretention device retrofits was investigated. A model was developed using parameters from an established hydrologic planning tool to determine the nitrogen removal capacity of POS in the study area. The scenario tested assumed 10% of POS be dedicated to the retrofits, forming a landscape-scale "treatment train". The current distribution of POS is estimated as being able to reduce stormwater nitrogen by 62% (7.8 tonnes) per year, posing significant benefits for stream and coastal conditions. Principles of landscape ecology were used to map the potential ecological value across the study area. The product of four indicators was used to quantify habitat quality in parks to promote biodiversity. Quantity of vegetation within 50m was used to indicate matrix conductivity, shortest distance to the next POS/patch provided a measure of connectivity and patch area was used to define patch size. Proximity to waterways and the stormwater trunk was preferred due to their common suitability for freshwater aquatic, avian and terrestrial species. The POS were attributed with each of the current and potential values and a sum of the four normalised values. The values characterise the contribution each POS makes for each function and as a whole. The results provide valuable insight into the distribution of spaces that possess high current and/or potential value at the landscape scale. Three local scale case studies are used to demonstrate how the approach can be used to identify and communicate the potential for improvements to an existing urban POS network. Possible applications for the decision support system to aid qualitative and quantitative assessments of POS design and management are discussed. The method developed supports decision-making to design spaces that best exploit their spatial context. It enables the protection of existing POS by managing them in a way that is aware of their function with respect to other landscape elements and to the landscape as a whole. The approach developed facilitates the communication of complex ideas to supplement park functionalities and the trade-offs between them. It can also promote discussion of competing priorities between managers, planners, the communities that use and value the spaces and across administrative boundaries. Concluding remarks are made on the challenges of this multidisciplinary approach and opportunities for further research.

School/Discipline

School of Earth and Environmental Sciences

Dissertation Note

Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2014

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This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals

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