•A dynamic, stock-driven bottom-up model is applied to the City of Melbourne, Australia.•Non-structural material replacement flows are calculated from 2018-2030 for each building.•Results show that ...the City of Melbourne required 26 kt of materials per year to maintain its current building stock.•Results show that plasterboard, carpet, timber and ceramics havethe highest average annual replacement rates.•This model supports decision-making for a more circular construction sector.
Humans are extracting and consuming unprecedented quantities of materials from the earth’s crust. The construction sector and the built environment are major drivers of this consumption which is concentrated in cities.
This paper proposes a framework to quantify, spatialise and estimate future material replacement flows to maintain urban building stocks. It uses a dynamic, stock-driven, and bottom-up model applied to the City of Melbourne, Australia to evaluate the status of its current material stock as well as estimated replacements of non-structural materials from 2018 to 2030. The model offers a high level of detail and characterises individual materials within construction assemblies for each of the 13 075 buildings modelled.
Results show that plasterboard (7 175t), carpet (7 116t), timber (6 097 t) and ceramics (3 500 t) have the highest average annual replacement rate over the studied time period. Overall, replacing non-structural materials resulted in a significant flow of 26 kt/annum, 36kg/(capita·annum) or 721t/(km2·annum). These figures were found to be compatible with official waste statistics. Results include maps depicting which material quantities are estimated to be replaced in each building, as well as an age pyramid of materials, representing the accumulation of materials in the stock, according to their service lives. The proposed model can inform decision-making for a more circular construction sector.
The extent of per- and polyfluoroalkyl substances (PFAS) in groundwater surrounding legacy landfills is currently poorly constrained. Seventeen PFAS were analysed in groundwater surrounding legacy ...landfills in a major Australian urban re-development precinct. Sampling locations (n = 13) included sites installed directly in waste material and down-gradient from landfills, some of which exhibited evidence of leachate contamination including elevated concentrations of ammonia-N (≤106 mg/L), bicarbonate (≤1,740 mg/L) and dissolved methane (≤10.4 mg/L). Between one and fourteen PFAS were detected at all sites and PFOS, PFHxS, PFOA and PFBS were detected in all samples. The sum of detected PFAS (∑14PFAS) varied from 26 ng/L at an ambient background site to 5,200 ng/L near a potential industrial point-source. PFHxS had the highest median concentration (34 ng/L; range: 2.6–280 ng/L) followed by PFOS (26 ng/L; range: 1.3–4,800 ng/L), PFHxA (19 ng/L; range: <LOQ – 46 ng/L) and PFOA (12 ng/L; range: 1.7–74 ng/L). Positive correlations between ∑14PFAS, PFOA and other perfluoroalkyl carboxylic acids (PFCAs) (e.g. PFHxA) with typical leachate indicators including ammonia-N and bicarbonate were observed. In contrast, no such correlations were found with perfluoroalkyl sulfonic acids (PFSAs) (e.g., PFOS and PFHxS). In addition, a strong positive linear correlation (R2 = 0.69) was found between the proportion of PFOA in the sum of detected perfluorinated alkylated acids (PFOA/∑PFAA) and ammonia-N concentrations in groundwater. This is consistent with previous research showing relatively high PFOA/∑PFAA in municipal landfill leachates, and more conservative behaviour (e.g. less sorption and reactivity) of PFCAs during subsurface transport compared to PFSAs. PFOA/∑PFAA in groundwater may therefore be a useful indicator of municipal landfill-derived PFAA. One site with significantly elevated PFOS and PFHxS concentrations (4,800 and 280 ng/L, respectively) appears to be affected by point-source industrial contamination, as landfill leachate indicators were absent.
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•Groundwater in Australia's largest urban re-development area was analysed for PFAS.•∑14PFAS varied from 26 up to 5,200 ng/L near a potential industrial point-source.•PFOA, PFHxA showed positive correlations with landfill leachate indicators.•Strong positive linear correlation observed between PFOA/∑PFAA and NH3N.•Groundwater PFOA/∑PFAA may be a useful tracer of municipal landfill-derived PFAS.
PFAS have been analysed in groundwater surrounding legacy landfills in a major urban re-development precinct in Australia, to better understand their sources, fate and transport.
The Scottish government has made the 20-minute neighbourhoods approach a priority. They are an important part of the nation’s plans for regeneration and its response to the climate crisis. Drawing on ...the model developed by Plan Melbourne, this paper discusses the application of the 20-minute neighbourhood concept in the established neighbourhoods of North Lanarkshire, Stirling and Dunblane from a community perspective. Based on the findings of a year-long project by Living Streets Scotland, it reminds planners and urbanists interested in creating low-traffic, 15- or 20-minute neighbourhoods or cities that listening to community viewpoints, in particular the voices of women, children, older and disabled people, is essential to their successful implementation. There is no ‘one size fits all’. Walking is literally a street-by-street issue. Every pavement, every crossing, every route — including longer journeys that cannot be walked or cycled — must be joined up for any of it to be accessible.
•Impacts of anthropogenic landscape change on groundwater recharge (GR) reviewed.•Agricultural and urban land conversion affect GR rates, locations and mechanisms.•Combination of tracer, physical and ...modelling techniques can be employed.•Quantifying effects of urbanisation on GR presents a major research challenge.
The impacts of anthropogenic modifications to the landscape on groundwater recharge rates, locations, and mechanisms are reviewed. The two major categories of change examined are conversion of land for agriculture and urbanization, both of which have significant effects on groundwater recharge. Techniques for identifying and quantifying the changes in recharge due to these impacts are discussed. Land-clearing for agriculture and surface water transfer for irrigation have resulted in order of magnitude increases in recharge rates in many semi-arid regions worldwide, causing ongoing land and water salinization and water-logging problems. While increased recharge by irrigation return flow may alleviate shallow groundwater depletion in some settings, this is complicated by the effect of unsaturated zone thickening, which reduces the fraction of potential recharge becoming actual recharge, and may result in new water quality risks such as nitrate contamination. Expansion of urban and peri-urban land and their associated surface and sub-surface infrastructure results in complex water balance changes that re-distribute groundwater recharge locations, modify recharge mechanism(s) and result in variable impacts on recharge rates (e.g., overall net decrease, increase or minimal change) and quality. While changes to groundwater recharge resulting from conversion of land for agriculture are relatively well understood, less is documented about the changes resulting from urbanization, due to a paucity of data from field-based studies. Two case studies from Beijing, China and Melbourne Australia are examined, which highlight these impacts and demonstrate some potential methodological techniques for this topic.
For much of the 19th and 20th centuries, Melbourne's Little
Lonsdale Street - locally known as 'Little Lon' - was notorious as
a foul slum and brothel district, occupied by the itinerant and the
...criminal. The stereotype of 'slumdom' defined 'Little Lon' in the
minds of Melbournians, and became entrenched in Australian
literature and popular culture.
The Commonwealth Block, Melbourne tells a different
story. This groundbreaking book reports on almost three decades of
excavations conducted on the Commonwealth Block - the area of
central Melbourne bordered by Little Lonsdale, Lonsdale, Exhibition
and Spring streets. Since the 1980s, archaeologists and historians
have pieced together the rich and complex history of this area,
revealing a working-class and immigrant community that was much
more than just a slum. The Commonwealth Block, Melbourne
delves into the complex social, cultural and economic history of
this forgotten community.
•Urban development and 1D-2D hydrodynamic modelling were coupled to assess flood risk.•Flood risk was driven by climate change as well as urban development.•The efficiency of adaptation measures ...depended on climate and population scenario.•Urban planning policies were efficient for reducing flood risk.
We present a new framework for flexible testing of flood risk adaptation strategies in a variety of urban development and climate scenarios. This framework couples the 1D-2D hydrodynamic simulation package MIKE FLOOD with the agent-based urban development model DAnCE4Water and provides the possibility to systematically test various flood risk adaptation measures ranging from large infrastructure changes over decentralised water management to urban planning policies. We have tested the framework in a case study in Melbourne, Australia considering 9 scenarios for urban development and climate and 32 potential combinations of flood adaptation measures. We found that the performance of adaptation measures strongly depended on the considered climate and urban development scenario and the other implementation measures implemented, suggesting that adaptive strategies are preferable over one-off investments. Urban planning policies proved to be an efficient means for the reduction of flood risk, while implementing property buyback and pipe increases in a guideline-oriented manner was too costly. Random variations in location and time point of urban development could have significant impact on flood risk and would in some cases outweigh the benefits of less efficient adaptation strategies. The results of our setup can serve as an input for robust decision making frameworks and thus support the identification of flood risk adaptation measures that are economically efficient and robust to variations of climate and urban layout.
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