Rashetnia, Samira (2024) Implementing Water Sensitive Urban Design approaches under the existing developments in urban area. PhD thesis, Victoria University.

Abstract

Urbanisation and population growth lead to increases in impervious area in urban catchments, which also brings more stormwater volume and increases pollutant loads. Consequently, the negative impacts of stormwater on freshwater have increased. Water Sensitive Urban Design (WSUD) techniques are becoming popular as they help planners and authorities to manage urban water resources in an integrated way to reduce the impacts of stormwater runoff on receiving environment. While research on Water Sensitive Urban Design (WSUD) has been ongoing for a considerable period, there are still gaps in our understanding of the scale, benefits, and effectiveness of implementing the systems, especially in the context of existing urban conditions. This study aims to address these knowledge gaps by exploring the optimal locations for implementing WSUD techniques implementation, at allotment and sub-catchment scales, with a focus on managing stormwater quantity and quality under the influences of urbanization and climate change in an urban catchment’s outlet. In addition, distributed WSUD implementation techniques at different scale were the focus of this research. Distributed systems mean to locate these approaches within smaller lots and at the available spaces throughout the development area. In contrast to greenfield developments, the implementation of WSUD in existing developments (suburbs) has various constraints and impediments. This research has identified the constraints and impediments for the selection of appropriate WSUD techniques for implementation in an existing development. Another component of this research was to identify the most prominent scale for WSUD implementation and develop a framework to identify WSUD assets spatially to achieve desired flow management and stormwater quality at a catchment outlet. Two urban catchments were selected for this study located in Wyndham City municipality in Melbourne’s west. Finding of this study advised that WSUD be taken into account as a potential solution in small sub-catchments to lower the study area's stormwater volume at the catchment outlet. In addition, the storm water system's load can be decreased by strategically putting WSUD techniques within the allotments or the available green open spaces. Though adding more WSUD techniques will not negatively impact a solution's performance, there are ways to promote acceptance among the community. As the effects of climate change continue to raise the risk, these solutions could also be examined in conjunction with other stormwater management techniques to see which one is the most economical in reducing the flow rate and volume of urban stormwater runoff. The findings indicate that the difference in total relative cost between optimal and nonoptimal solutions can reach well below $20 million dollars, and the effectiveness of load reduction for both stormwater quality and quantity at the study catchment could vary as much as 33% to 40% adopting a combination of raingardens, infiltration trenches and permeable pavements. Modelling and optimization in this study showed that, when applied in small sub-catchments, WSUD techniques performed better in terms of improving stormwater quality and reducing stormwater quantity. The improvement at a catchment scale was led to the same outcomes, as demonstrated by a comparison of two urban catchments and WSUD techniques implementation in extremely small and larger catchments size from 2 ha. The study outcomes will help local governments and relevant organisations manage their stormwater Master plans to make urban areas more sustainable and liveable.

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