AbstractRiffles are heterogeneous habitats that support diverse assemblages in natural streams. They are often constructed as part of stream restoration practice, including in degraded urban stream ecosystems, despite larger scale limits to ecological state. Such restoration practices fail to consider ecological theory, and their outcomes have rarely been robustly monitored and assessed. We assessed the effects of constructed rock riffles on habitat heterogeneity and on macroinvertebrate assemblages in six urban streams (4%–32% effective imperviousness). We compared habitat heterogeneity, and taxon abundance and richness of the six streams before and after (1 and 5 years) riffle construction and in three control streams without riffles. Riffles increased habitat heterogeneity. In contrast, macroinvertebrate assemblages in all streams were dominated by tolerant, cosmopolitan, and invasive taxa before and after riffle construction. Riffles reduced the abundance and richness of tolerant taxa in less urbanized streams and increased their richness in more urban streams. These changes had no effect on measures of biodiversity. Urban stormwater runoff can affect the degree to which rock riffles increase habitat heterogeneity through sediment transport and increased physical disturbance. In highly urban streams, increased habitat heterogeneity is likely to primarily favor cosmopolitan species that can tolerate frequent chemical and physical disturbance. Riffle construction may reduce the abundance of cosmopolitan species and increase the abundance of more sensitive species, but only if catchment‐scale impacts of urban stormwater runoff are adequately controlled. Robust experiments such as this add to general understanding of the effectiveness of restoration practice, reducing the need for ubiquitous monitoring of restoration projects.

Greywater is being increasingly used as an alternative water source to reduce potable water demand and to alleviate pressure on sewerage systems. This paper presents the development of a low energy and low maintenance greywater treatment technology: a living wall system, employing ornamental plants (including vines) grown in a sand filter on a side of a building to treat shower, bath, and washing basin wastewaters. The system can, at the same time, provide critical amenity and micro-climate benefits to our cities. A large scale column study was conducted in Melbourne, Australia, to investigate the following design and operational factors of the proposed system: plant species, saturated zone design, rest period, hydraulic loading rate and pollutant inflow concentration. The results indicate that the use of ornamental species (e.g. Canna lilies, Lonicera japonica, ornamental grape vine) can contribute to pollutant removal. Vegetation selection was found to be particularly important for nutrient removal. While a wider range of tested plant species was effective for nitrogen removal (>80%), phosphorus removal was more variable (−13% to 99%) over the study period, with only a few tested plants being effective - Carex appressa and Canna lilies were the best performers. It was also found that phosphorus removal can be compromised over the longer term as a result of leaching. Excellent suspended solids and organics removal efficiencies can be generally achieved in these systems (>80% for TSS and >90% for BOD) with plants having a relatively small impact. Columns had an acceptable infiltration capacity after one year of operation. When planted with effective species (e.g. Carex appressa and Canna lilies), it is expected that performance will not be significantly affected by longer rest periods and higher pollutant concentrations in the early years of system operation. The results of this study, thus, demonstrate that innovative and aesthetically pleasing living walls can be designed for treatment of greywater at the household scale.

An external electron donor is usually included in wastewater and groundwater treatment systems to enhance nitrate removal through denitrification. The choice of electron donor is critical for both satisfactory denitrification rates and sustainable long-term performance. Electron donors that are waste products are preferred to pure organic chemicals. Different electron donors have been used to treat different water types and little is known as to whether there are any electron donors that are suitable for multiple applications. Seven different carbon rich waste products, including liquid and solid electron donors, were studied in comparison to pure acetate. Batch-scale tests were used to measure their ability to reduce nitrate concentrations in a pure nutrient solution, light greywater, secondary-treated wastewater and tertiary-treated wastewater. The tested electron donors removed oxidised nitrogen (NOx) at varying rates, ranging from 48 mg N/L/d (acetate) to 0.3 mg N/L/d (hardwood). The concentrations of transient nitrite accumulation also varied across the electron donors. The different water types had an influence on NOx removal rates, the extent of which was dependent on the type of electron donor. Overall, the highest rates were recorded in light greywater, followed by the pure nutrient solution and the two partially treated wastewaters. Cotton wool and rice hulls were found to be promising electron donors with good NOx removal rates, lower leachable nutrients and had the least variation in performance across water types.

: This paper demonstrates a new way to integrate green infrastructure in the urban design of our cities whilst they continue to increase in density. A pilot study demonstrates how the population may be doubled through sensitive infill of the inner-city Brisbane neighbourhoods situated in the historical catchment of Western Creek. Hydrological modelling used MUSIC to size the associated green infrastructure elements and to quantify the benefits in terms of stormwater improvements. The Western Creek Pilot Study reveals the important role that multifunctional green infrastructure has to play in the development of local solutions to urban intensification in response and energy, land, food and water supply pressures as part of a climate change adaptation strategy.

Biofiltration systems are an effective technology for removal of nitrogen from stormwater. It has recently been proposed to harness these systems for treatment of other water types (such as light wastewater and polluted groundwater) during dry weather periods. Light wastewater, namely greywater and secondary treated wastewater contains nitrogen at levels five to ten times higher than stormwater. At present, these systems cannot effectively attenuate nitrogen at such concentrations primarily as a result of limited denitrification rates. The objective of this study was thus to identify suitable electron donors that can promote rapid denitrification in the lower saturated zone of biofiltration systems. Eight different carbon substrates comprising both liquid and solid materials were selected, namely cracked corn, rice hulls, cotton, hardwood, softwood, brewer’s spent grain, brewery wastewater and sodium acetate. Batch scale denitrification tests were conducted to study their nitrate removal rates in a pure nutrient medium, light greywater and secondary treated wastewater. The relative removal efficiencies after 48 hours of incubation in the pure nutrient medium was: sodium acetate > cotton > spent grain > rice hulls > brewery waste > cracked corn > softwood > hardwood. The results found that light greywater possesses sufficient biological oxygen demand to induce satisfactory denitrification rates. Spent grain, cotton and rice hulls are promising

An asset management model for natural and constructed water bodies has been developed for Logan City Council which identifies clear management targets in the form of 'benchmark levels of service'. This pragmatic approach provides a clear vision for the minimum requirements that need to be met for a water body to support its inherent values and to meet statutory obligations and community expectations. Benchmark levels of service were defined for Logan's constructed urban lakes, naturalised lakes, natural wetlands, stormwater treatment ponds and stormwater treatment wetlands. The benchmarks are tailored to reflect primary function (related to water body type) and community value (related to location, visitation and use). The benchmarks define the characteristics or conditions required to achieve minimum acceptable standards for water quality, hydrology, ecological habitat, public health and safety and recreation and amenity. This enables the current condition and function of a water body to be assessed against the minimum acceptable standards. The benefit of defining benchmarks is that it provides a clear vision for coordinated management of water body assets across Council departments and facilitates communication with stakeholders and the community. This approach aligns with asset management models for hard infrastructure, enables budget requirements to be clearly communicated and importantly provides a basis for measuring the effectiveness of management actions. This asset management model provides a template that could be applied to other green infrastructure assets such as waterways and water sensitive urban design.

The potential for a city to act as a water supply catchment is now well recognised. Wastewater recycling and stormwater reuse can provide resilience to the impacts of drought, climate change and bushfire on natural catchment supplies. Numerous schemes are now being designed and constructed and a key challenge is the coordination of individual schemes to provide the best and most cost effective outcomes. A master plan was developed for non potable water reuse for Canberra. It encompassed identified potential sources of non potable water including treated wastewater, stormwater reuse and aquifer storage, transfer and recovery. Non potable demands including irrigation of public open space as well as irrigation and toilet flushing for new developments were considered. A model was used to develop the master plan and 'game' various scenarios. The model represents the volumetric distribution of flows from the various sources to a range of demands through a reticulation network and estimates the size and cost of infrastructure including storages, pipes, pumps and treatment. The analysis indicated that an integrated multiple source approach provided the best outcomes in terms of yield, cost effectiveness and resilience. To achieve the ultimate goal of a water sensitive city with a non potable water supply network it was apparent that further planning and construction must commence immediately.

Integrated water cycle management often uses diverse water supplies to reduce demands on potable water. The drivers to reduce potable water demands include a) supply scarcity, b) negative impacts on the supply catchments (flow disruption and flooding from storages), and c) high energy use, cost and pollution (desalination). Alternative water supplies may be considered for non-potable uses if the water quality is suitable for the demand i.e. fit-for-purpose. Evaluations of alternative water sources are predominantly based on human exposure to pathogens and cost. Environmental impacts and benefits of alternative water supplies are often under-represented. For example, it is common practice to discharge polluted wastewaters and to allow stormwater runoff to flow untreated to receiving environments. Yet, these practices result in substantial loss of biodiversity values and ecosystem functions, and the creation of human health hazards requiring remediation. Therefore, a risk assessment was designed specifically to determine the likelihood and consequence for environmental hazards associated with the use of wastewater and stormwater as alternative sources for irrigation of public open space. The consequence scores followed Standards Australia protocol. The descriptions of effects were customised for environmental impacts, being based on biodiversity and ecosystem function. The assessment revealed that current practices of discharging wastewater and stormwater to receiving waterways have very high likelihood and consequence scores for environmental hazards, associated with high pollutant loads and changes in hydrology. The use of wastewater and stormwater as alternative water supplies mitigates these high risks, and confers substantial benefits to existing impacted environments.

Recent attempts to measure likely impacts of climate change on WSUD measures have focused on performance under a single scenario of adjusted historical rainfall and evaporation. This study adopted an approach whereby a limited number of time series were generated to represent the extremes of a number of projected ranges of climate change scenarios. To support the Mornington Peninsula Shire's Integrated Water Management plan, analysis was undertaken to ensure that future stormwater management strategies were adaptable to a range of possible climate change conditions. Six different scenarios were developed, using stochastic downscaling of historical rainfall and evaporation, to represent predicted climate adjusted conditions under various emissions scenarios. Pollutant generation across the entire municipality and various WSUD measures were modelled under each of climate change scenarios to better understand the sensitivities of both pollutant generation, and resilience of treatment measures including wetlands, raingardens, stormwater harvesting and rainwater tanks to the likely future changes in climate. Results were then used to determine appropriate design considerations for various WSUD measures as well as recommend appropriate climate change adaptations for a number of biological components of these systems such as wetland vegetation.

Despite experiencing recent drought conditions, Israel is expected to discharge more than 150 GL of urban runoff to sea due to extensive urbanization along the coastal plains. The underlying aquifer, a vital water resource, has become contaminated mainly by nitrate. Stormwater biofilters, have been demonstrated to be effective for stormwater treatment. A dual-mode biofiltration system has been constructed in Kfar-Sava to combine stormwater harvesting and treatment during the wet season, while being used to treat polluted aquifer groundwater (aquifer recovery) during the dry season. In addition to demonstrating treatment effectiveness, direct and infiltration recharge options of the treated water were tested to determine their relative efficiency. The preliminary results show that the system was able to effectively treat a range of pollutants in urban runoff (heavy metals, nutrients and pathogens) and meet Israeli and Australian guidelines for irrigation, aquifer recharge and streams health. Initial aquifer recovery tests show up to 73% nitrate removal of aquifer polluted water at low biofiltration rates. The Kfar-Sava biofilter marked an important milestone for implementing Water Sensitive Urban Design (WSUD) principles in the Israel and in the next two years Israel will gain at least two pilot systems across the country, with the aim being to establish policies and process to underpin widespread adoption.

Climate change, and the corresponding influence on ecological habitats, is increasingly being felt by communities as natural systems struggle to respond to the pressures of changes in temperatures, rainfall and other climatic parameters. In the context of Melbourne, and the south east seaboard of Australia in general, projections are for reductions in the mean annual rainfall with elevated temperatures and increasing evapotranspiration from vegetated landscapes (CSIRO and BoM, 2007). The anticipated rise in sea level and the effects of sustained droughts on non-indigenous parkland landscapes have increasingly been reported in mainstream media and are fairly well understood by residents and practitioners. The impacts of climate change on indigenous vegetation is however, less widely reported and is often overlooked when local councils table initiatives to promote resilience to future climate predictions. Within the metropolitan boundaries of most cities and towns, pockets of remnant bushland remain amongst the highly modified urban landscape. These remnants are generally protected assets and highly valued by the community for the numerous intangible benefits that they provide as well as their biogeographic significance. These pockets of indigenous vegetation communities support biodiverse flora and provide a refuge for native fauna. The assumption that, remnant indigenous landscapes will be resilient to future extreme weather patterns and will be capable of rapid adaptation, risks jeopardising their existence in our urban environment. Rapid adaptation, if it were to occur, could be expected to require contiguous vegetation communities which are not supported in urban environments. This will in turn reduce the biodiversity of flora and fauna in the urban setting and potentially alienate residents from the habitat which evolved in localities prior to widespread development.