Written by Tom de Aizpurua
Major cities can play a vital role in creating biodiversity gains through Nature Based Solutions (NBS). Finding space in dense and heavily congested urban environments is difficult, but research conducted at ICON Science shows that remodelling redundant car spaces to make way for green space could solve many city issues, including of flood management and over-heating, while making significant biodiversity gains. We investigated how this thinking could be applied to the City of Melbourne to help overcome the significant challenges of biodiversity loss, urban heat island effects and flooding. You read the full paper here.
To find space suitable for NBS, we collated up to 11,668 redundant on-street car parking spaces. These spaces represent 47% of the total on-street spaces in the city and cover approximately 50ha of impermeable land. There are 193,500 garage spaces scattered across the city that are either vacant or are underused. The proposed plan focused on remodelling only redundant on-site parking located within a 200m distance to ‘commercial’, ‘residential’ or ‘private’ garage parking, allowing acceptations for disabled and delivery parking. These spaces were replaced with parklets (see figure 1 below), designed following Biodiversity Sensitive Urban Design (BSUD) principles, also accommodating different social uses – such as outdoor dining spaces for commercial areas.
Conversion of redundant on-street parking to small green spaces could result in an increase of up to 59ha of tree canopy cover, adding to the already 254ha of current cover and contributing to a third of the City of Melbourne’s target of 40% tree canopy cover on public land by 2040. The tree plantings selected in the project include Allocasuarina, Eucalyptus and Melaleuca species, all of which provide an ecological benefit that allows for habitat connectivity.
The re-modelled parking spaces can act as important biodiverse stepping stones, supporting charismatic native wildlife such as the Blue Banded Bee (Amegilla cingulata) and the New Holland Honeyeater (Phylidonyris novaehollandiae). This project observed greater connectivity outcomes for the New Holland Honeyeater, but the Blue Banded Bee showed the most improvement.
The proposed rain garden design can capture up to 27 tonnes of gross pollutants, over 200 tons of sediment as well as nutrient pollutants such as nitrogen and phosphorus, exceeding the sediment and phosphorus targets outlined by City of Melbourne’s 2009 total watermark strategy.
This project identified that a total of 24.5 ha of car space could be de-paved in the City of Melbourne. That equated to approximately 1.5 and 6 city blocks. Additionally, there is up to 7.7ha of de-paving opportunities within the flood prone Elizabeth Street Catchment. This is a major contribution to the 65ha flood management target outlined by the City of Melbourne.