What drives the location choice for water sensitive infrastructure in Melbourne, Australia?

Distributed and green urban drainage infrastructure known as Water Sensitive Urban Design (WSUD) is increasingly being implemented in cities globally to combat climate change and urbanisation effects. Rigorous consideration of the urban context in terms of biophysical, socio-economic and urban form related factors is crucial for optimal design outcomes. The extent to which the urban context is considered in current planning and decision-making processes remains unclear. This study investigates this relationship between current WSUD infrastructure in Melbourne (Australia) and each of the aforementioned factors for the first time. We obtained and pre-processed one of the most extensive and complete geo-located WSUD asset databases in the world (containing over 2000 WSUD assets), and undertook an evidence-based analysis of WSUD planning outcomes. Relationships were investigated using spatial analysis techniques (e.g. overlaying), as well as a number of statistical methods (e.g. exploratory regression). It was found that biophysical and urban form factors strongly explained variability in WSUD location choice, while socio-economic factors appeared to be overlooked. Our findings imply that the current WSUD planning practices are primarily governed by standard engineering design. Opportunistic WSUD planning leads to unintentional outcomes that fail to capitalise on the full potential of WSUD benefits. Increased investment in asset inventory development and analysis is critical to inform WSUD planning moving forward. Knowledge gained from this and additional studies can further planning through application in planning-support systems, to deal with the complexity and diversity of the broad set of decision criteria.