Water Sensitive Urban Design: An Investigation of Current Systems, Implementation Drivers, Community Perceptions and Potential to Supplement Urban Water Services

Management of the designed risk level of urban drainage system in the future: Evidence from haining city, China

The design of urban drainage infrastructure is mainly based on historical conditions. Under global warming, more intense precipitation extremes will pose severe risk to current infrastructure. The evaluation of where and by how much design standards need to change, is urgently needed to help maintain well-functioning drainage systems. In this study, we used climate projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and InfoWorks Integrated Catchment Modeling (ICM) to simulate urban flooding. According to the latest design standard of urban drainage infrastructure, we assess the risk of future urban flooding, and evaluate the effect and benefit of drainage infrastructure adaptation measures. The results showed that, under the shared socioeconomic pathway (SSP) 5-8.5 scenario, a 35% increase in extreme rainfall would be expected. Under a 1-in-30-year precipitation event, the maximum depth would increase by 5.59%, and the withdrawal time would rise by 2.94% in the future period, relative to the baseline level. After the enlargement of drainage infrastructure in local areas, 10% pipe enlargement has a better effect to reduce risk and higher benefits than 5% pipe enlargement. These findings provide valuable insights for policymakers in enhancing the drainage system and adapting to climate change.

Low-cost monitoring systems for urban water management: Lessons from the field

Sound urban water management relies on extensive and reliable monitoring of water infrastructure. As low-cost sensors and networks have become increasingly available for environmental monitoring, urban water researchers and practitioners must consider the benefits and disadvantages of such technologies. In this perspective paper, we highlight six technical and socio-technological considerations for low-cost monitoring technology to reach its full potential in the field of urban water management, including: technical barriers to implementation, complementarity with traditional sensing technologies, low-cost sensor reliability, added value of produced information, opportunities to democratize data collection, and economic and environmental costs of the technology. For each consideration, we present recent experiences from our own work and broader literature and identify future research needs to address current challenges. Our experience supports the strong potential of low-cost monitoring technology, in particular that it promotes extensive and innovative monitoring of urban water infrastructure. Future efforts should focus on more systematic documenting of experiences to lower barriers to designing, implementing, and testing of low-cost sensor networks, and on assessing the economic, social, and environmental costs and benefits of low-cost sensor deployments.

Understanding the linkages between spatio-temporal urban land system changes and land surface temperature in Srinagar City, India, using image archives from Google Earth Engine

Land-use and land-cover (LULC) is an important component for sustainable natural resource management, and there are considerable impacts of the rapid anthropogenic LULC changes on environment, ecosystem services, and land surface processes. One of the significant adverse implications of the rapidly changing urban LULC is the increase in the Land Surface Temperature (LST) resulting in the urban heat island effect. In this study, we used a time series of Landsat satellite images from 1992 to 2020 in the Srinagar city of the Kashmir valley, North-western Himalaya, India to understand the linkages between LULC dynamics and LST, derived from the archived images using the Google Earth Engine (GEE). Furthermore, the relationship between LST, urban heat island (UHI), and biophysical indices, i.e., Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI), was also analysed. LULC change detection analysis from 1992 to 2020 revealed that the built-up area has increased significantly from 12% in 1992 to 40% in 2020, while the extent of water bodies has decreased from 6% in 1992 to 4% in 2020. The area under plantations has decreased from 26% in 1992 to 17% in 2020, and forests have decreased from 4 to 2% during the same period. Urban sprawl of Srinagar city has resulted in the depletion of natural land covers, modification of natural drainage, and loss of green and blue spaces over the past four decades. The study revealed that the maximum LST in the city has increased by 11°C between 1992 and 2020. During the same period of time, the minimum LST in the city has increased by 5°C, indicating the impact of urbanization on the city environment, which is reflected by the observed changes in various environmental indices. UHI impact in the city is quite evident with the maximum LST at the city centre having increased from 13.03°C in 1992 to 22.01°C in 2020. The findings shall serve as a vital source of knowledge for urban planners and decision-makers in developing sustainable urban environmental management strategies for Srinagar city.

Scientific challenges and biophysical knowledge gaps for implementing nutrient offset projects

Nutrient offsetting allows nutrient point source polluters to pay for diffuse source nutrient reductions, or improvements in nutrient load reductions from alternative point sources. These programs have the potential to provide a more cost-effective approach to achieve water quality goals in waterways compared to infrastructure upgrades. However, worldwide adoption of nutrient offset/trading has not been realized. Here, we identified the biophysical-chemical knowledge gaps that can act as barriers to adopting these programs and summarized areas where further research is needed. This includes a) evaluating if any appropriate spatial scale (local-, catchment-, or regional-scale) and time scale (especially for areas with dry/wet cycles) exists to achieve nutrient load management goals, and b) quantifying nutrient characteristic differences and load contributions between point and diffuse sources to determine possible offsets between the two. Where offsets are appropriate, there is also a need to 1) improve monitoring design and reduce modelling uncertainties to better quantify diffuse nutrient loads; 2) quantify and manage uncertainties in catchment interventions to reduce nutrient loads, and design effective long-term monitoring and maintenance to sustain intervention outcomes; 3) prioritize areas within catchments that are key nutrient sources for catchment interventions to achieve the optimal outcomes for nutrient load management and catchment and aquatic ecosystem health; and 4) develop methodologies to determine the environmental equivalency ratio between different nutrient sources in terms of ecosystem effects. This would include identifying the best metric to quantify equivalency ratios, determining discharge patterns for different nutrient sources, and linking this with ecosystem responses across seasons and in the downstream receiving environment. Addressing the identified knowledge gaps will improve the program feasibility assessment process as well as confidence and certainty in the environmental outcomes of nutrient offsetting.

Assessing the link between land use/land cover changes and land surface temperature in Himalayan urban center, Srinagar

The rapidly growing urbanization and the consequent land use/land cover (LULC) changes have resulted in unsustainable growth of cities in Indian subcontinent especially in Himalayan region which are highly sensitivity to condition like climate change. Using multi-temporal and multi-spectral satellite datasets, this study analyzes the impact of LULC changes on land surface temperature (LST) in the Himalayan city of Srinagar from 1992 to 2020. For LULC classification, the maximum likelihood classifier technique was utilized, and to extract LST from Landsat 5 (TM) and Landsat 8 (TM) (OLI), spectral radiance was employed. The results show that, among various LULC classes, built-up area has seen a maximum increase of 14% while agriculture has decreased by about 21%. On the whole, Srinagar city has witnessed an increase in LST by 4.5 °C with maximum increase of 5.35 °C especially over marshes and a minimum increase of 4 °C on agriculture landscape. Other LULC categories of built-up, water bodies, and plantation saw an increase in LST by 4.19 °C, 4.47 °C, and 5.07 °C, respectively. The transformation of marshes into built-up saw a maximum increase in LST by 7.18 °C followed by water body to built-up (6.96 °C) and water body to agriculture (6.18 °C) while minimum increase was seen in the conversion of agriculture to marshes by about 2.42 °C followed by agriculture to plantation (3.84 °C) and plantation to marshes (3.86 °C). The findings may be useful to urban planners and policymakers in terms of land use planning and city thermal environment control.

Water Value Integrated Approach: A Systematic Literature Review

Extreme water incidents point out a value conflict surrounding the resource. While drought and floods echo the inadequate land and resource uses, the increase in social inequalities exposes the practical, physiological, and social consequences. The multiple value action throughout the water cycle also narrowed disputes to those that neglect its vital importance, and the constraints imposed to the services, such as low tariffs, and lack of local engagement, make sustainable water systems more difficult. This article develops a systematic literature review to understand the academic motivations surrounding water value and gaps in its systematic approach. A sample with 84 papers is created by an interactive keyword selection and its general characteristics are presented. A dynamic reading technique extracts data and classifies the papers according to 14 research motivations, where the water multifunctionality and the user value stand out. The bibliographic coupling analysis identifies a cluster of 16 papers related to integration and connected to planning, decision, and management. There is a lack of contribution with a systemic approach to water resources by way of integrating actors and values, such as including local contexts.

What roles do architectural design and on-site water servicing technologies play in the water performance of residential infill?

More than half of new urban residential developments are planned as infill in Australia's major cities. This provides an unprecedented opportunity to use innovative design and technology to address urban water challenges such as flooding, reduced water security and related infrastructure and urban heat island issues. However, infill can have positive or negative water impacts, depending on architectural design and on-site water servicing technologies implemented. In this study we asked, "What influence does residential infill development have on the local urban water cycle?" and "What roles do architectural design and technologies play?" To answer these questions, a set of 196 design-technology configurations were developed by combining 28 architectural designs and 7 on-site water-servicing technology options. The configurations represent three cases: (i) existing (EX) or before infill, (ii) business-as-usual development (BAU), and (iii) alternative development (ALT). Using the Site-scale Urban Water Mass Balance Assessment (SUWMBA) model and a set of water performance indicators, the impact of configurations on the urban water cycle was quantified. The results showed BAU, on average, increases population density, stormwater discharge, and imported water by 98%, 44% and 85%, and decreases evapotranspiration and infiltration by 53% and 34%, compared to the EX conditions. More population density (141%) with lower impacts on the urban water cycle (21% and 64% increase for stormwater discharge and imported water, and 29% and 17% reduction in evapotranspiration and infiltration) can be achieved by appropriate integration of ALT designs and technologies. Architectural design has a greater influence on urban water flows than the implementation of on-site water servicing technologies. The results have a great implication for sustainable urban water management for managing the risks associated with pluvial flooding, water insecurity, and urban heat. It also highlights the underutilised role of architects and urban planners to address urban water issues.

People’s Perception of Nature-Based Solutions for Flood Mitigation: The Case of Veneto Region (Italy)

Floods have become more frequent due to a growing number of extreme rainfall events linked to climate change and increased urbanization. Additionally, 66% of the world’s population is expected to live in urban areas by 2050, making flood prevention and risk reduction increasingly important. Sustainability, resilience and ecosystem services are essential to increase human well-being in urban environments. Nature-based Solutions (NBS) can provide all the benefits of urban green spaces combined with flood mitigation. This work aims to provide useful information to promote the adoption of NBS to build communities resilient to climate change by exploring how people’s perception of and willingness to implement some NBS. To this end, an online survey was conducted to investigate the knowledge and the perception of NBS and grey infrastructures among people in Veneto, a north-Eastern region of Italy. Data analysis revealed a significant correlation between previous knowledge of water management systems and the perceived effectiveness of some NBS. Behaviors linked to the level of connection with the territory have also been found to influence the perceived effectiveness of NBS. This study provides insights into the dynamics behind the implementation of NBS to reduce the risk of urban flooding and can help policymakers adapt urban plans to promote the adoption of NBS.

Assessment of Blue and Green Infrastructure Solutions in Shaping Urban Public Spaces—Spatial and Functional, Environmental, and Social Aspects

Blue and Green Infrastructure (BGI) provide one of the key Nature Based Solution (NBS) approaches for sustainable stormwater management in cities, in conjunction with extending the scope of Ecosystem Services (ES). In both the process of planning and designing highly urbanized areas, the implementation of BGI is important for the improvement of living conditions and counteracting the negative effects of climate change. Based on the literature review, 19 BGI solutions were identified and then valorized in relation to the following three key aspects: spatial and functional, environmental, and social. The results of the assessment were derived using the scoring method and allowed for the identification of BGI solutions with a high, medium or low value for shaping sustainable urban public spaces. Using the potential of analyzed BGI solutions to improve the functioning and attractiveness of urban areas requires a comprehensive approach. Conscious planning and designing should use the knowledge presented to make the implementation of BGI solutions as effective as possible in relation to the above-mentioned aspects of shaping urban public spaces.

Co-design of experimental nature-based solutions for decentralized dry-weather runoff treatment retrofitted in a densely urbanized area in Central America

The quality of water in many urban rivers in Latin America is increasingly degrading due to wastewater and runoff discharges from urban sprawl. Due to deficits in sanitary drainage systems, greywater is discharged to the stormwater drainage network generating a continuous dry-weather runoff that reaches rivers without treatment. One of the main challenges in the region is to achieve sustainable management of urban runoff for the recovery of rivers ecosystem integrity. However, retrofitting conventional centralized wastewater drainage networks into the existing urban grid represents important social, economic and technical challenges. This paper presents an alternative adaptive methodology for the design of Nature-based Solutions for decentralized urban runoff treatment. Through this study, technical solutions commonly used for stormwater management were adapted for dry-weather runoff treatment and co-designed for the particular conditions of a representative study area, considering space availability as the main constraining factor for retrofitting in urban areas. The application of a co-design process in a dense neighbourhood of the Great Metropolitan area of Costa Rica brought to light valuable insights about conditions that could be hindering the implementation of NBS infrastructures in Latin America.

International Perceptions of Urban Blue-Green Infrastructure: A Comparison across Four Cities

Blue-Green infrastructure (BGI) is recognised internationally as an approach for managing urban water challenges while enhancing society and the environment through the provision of multiple co-benefits. This research employed an online survey to investigate the perceptions of BGI held by professional stakeholders in four cities with established BGI programs: Newcastle (UK), Ningbo (China), Portland (Oregon USA), and Rotterdam (The Netherlands) (64 respondents). The results show that challenges associated with having too much water (e.g., pluvial and fluvial flood risk, water quality deterioration) are driving urban water management agendas. Perceptions of governance drivers for BGI implementation, BGI leaders, and strategies for improving BGI uptake, are markedly different in the four cities reflecting the varied local, regional and national responsibilities for BGI implementation. In addition to managing urban water, BGI is universally valued for its positive impact on residents’ quality of life; however, a transformative change in policy and practice towards truly multifunctional infrastructure is needed to optimise the delivery of multiple BGI benefits to address each city’s priorities and strategic objectives. Changes needed to improve BGI uptake, e.g., increasing the awareness of policy-makers to multifunctional BGI, has international relevance for other cities on their journeys to sustainable blue-green futures.

Community Perceptions and Knowledge of Modern Stormwater Treatment Assets

Modern stormwater treatment assets are a form of water sensitive urban design (WSUD) features that aim to reduce the volumes of sediment, nutrients and gross pollutants discharged into receiving waterways. Local governments and developers in urban areas are installing and maintaining a large number of stormwater treatment assets, with the aim of improving urban runoff water quality. Many of these assets take up significant urban space and are highly visible and as a result, community acceptance is essential for effective WSUD design and implementation. However, community perceptions and knowledge about these assets have not been widely studied. This study used a survey to investigate community perceptions and knowledge about stormwater treatment assets in Brisbane, Australia. The results suggest that there is limited community knowledge of these assets, but that communities notice them and value their natural features when well-maintained. This study suggests that local governments may be able to better inform residents about the importance of these assets, and that designing for multiple purposes may improve community acceptance and support for the use of Council funds to maintain them.

Analyzing Evidence of Sustainable Urban Water Management Systems: A Review through the Lenses of Sociotechnical Transitions

Sustainability concerns and multiple socio-environmental pressures have necessitated a shift towards Sustainable Urban Water Management (SUWM) systems. Viewing SUWM systems as sociotechnical, this paper departs from eight factors previously identified by transition research: Pressures, Context, Purposes, Actors, Instruments, Processes, Outputs, and Outcomes as a methodological framework for a structured review of 100 articles. The study seeks to analyze empirical cases of planning and implementing SUWM systems worldwide. A wide range of public actors—driven by social and environmental factors rather than by economic pressures—have initiated SUWM projects so as to locally fulfill defined social and environmental purposes. We provide evidence on the emergence of new actors, such as experts, users, and private developers, as well as on the diverse and innovative technical and societal instruments used to promote and implement SUWM systems. We also explore their contexts and institutional capacity to deal with pressures and to mobilize significant financial and human resources, which is in itself vital for the transition to SUWM. Planned or implemented SUWM outputs are divided into green (wet ponds, raingardens, and green roofs) and gray (rain barrels and porous pavements) measures. The outcomes of SUWM projects—in terms of societal and technical learning, and their institutional uptakes—are often implicit or lacking, which seemingly reduces the rate of desirable change.

Development Trend and Frontier of Stormwater Management (1980–2019): A Bibliometric Overview Based on CiteSpace

The threat of urban floods due to climate change and urbanization has enabled sustained attention to the stormwater management field. Numerous scholars and countries have successively proposed innovative concepts for stormwater management. To grasp the current research focus and status quo and determine the development trend and dynamic direction, this work used CiteSpace, a scientific bibliometric analysis software, to analyze and identify 3080 articles based on the core database of Web of Science from 1980 to 2019. Results show a comprehensive overview of the stormwater management field, including the changes of annual articles with time; the most influential countries, institutions, authors, and articles; and the periodical keywords, highly cited papers, and burst time in the field. A knowledge table in the stormwater management field was obtained, the development context of the field and the research focus of each stage were understood, and the future development trend of the field is inferred. This study aims to provide reference for researchers and practitioners in the stormwater management field.

A Framework to Evaluate Urban Flood Resilience of Design Alternatives for Flood Defence Considering Future Adverse Scenarios

In urbanized plains that are subject to flooding, the socioeconomic aspects, climate characteristics, built environment, and riverine processes exhibit bi-univocal relationships with the flood formation itself, creating a pattern of development without a predefined equilibrium state. The complexity of processes involved in flood management and the need for a comparative assessment method to hierarchise different design alternatives or planning scenarios requires practical and quantitative methods for urban diagnoses, including flood risk and resilience aspects. This paper proposes an alternative pathway to evaluate design alternatives for urban flood mitigation, assessing resilience in quantitative terms. In this way, a methodological framework is presented with which to evaluate flood resilience in urban watersheds planning, through the application of the Urban Flood Resilience Index (UFRI) and Future Scenarios Criteria (FSC). A case study illustrates the method using an urban watershed in Rio de Janeiro/Brazil. This study considered two possible design alternatives for flood control, with concentrated and distributed measures. The resilience mapping using the UFRI showed that the adoption of distributed measures could increase the areas classified as showing very high resilience by 41%, while very low resilience areas would be reduced by 87%. The FSC is able to present the integrated results of resilience variation from present and future conditions, considering, for example, climate change effects or unplanned urbanisation scenarios. The framework is able to perform comparisons between alternatives, showing the advantages associated with adopting distributed measures over the watershed, which reflected in a resilience value that was 24% higher when compared to the results obtained for the concentrated solutions scenario.

Key Factors Influencing Wider Adoption of Blue–Green Infrastructure in Developing Cities

Numerous fast-growing coastal cities in the Global South are exposed to coastal, fluvial and pluvial floods, as a consequence of decades-long rapid urbanisation and weak enforcement of planning regulations. Integrating Blue–Green Infrastructure (BGI) concepts into the development of the urban landscape has the potential to increase flood resilience and offer broader environmental benefits. BGI is an innovative approach that combines water management and green infrastructure to maintain natural water cycles and enhance environmental and urban renewal. This paper identifies socio-economic, cultural and political challenges influencing BGI adoption in Semarang city in Indonesia. Data was collected from residents of three communities through interviews (n=30), questionnaires (n=180) and focus groups with policymakers and community representatives. The combined quantitative and qualitative data provide an understanding of the specific socio-economic, cultural and political issues at play and reveal flood experience as well as perceptions of community members regarding flood management. Challenges are presented from the point of view of residents and local policymakers and are based on a framework for facilitating local BGI adoption, setting the principles of “inclusive”, “appropriate” and “proactive” as pre-conditions for enhancing community resilience to flooding.

Use of detention basin for flood mitigation and urban requalification in Mesquita, Brazil

Unplanned urbanization is one of the main factors responsible for worsening flood-related problems in cities, increasing the frequency of flooding and flooding depths, consequently degrading both the natural and built environment. Considering this, the use of engineering techniques that reduce runoff and promote urban requalification are an efficient option for managing rainwater. This paper presents a case study of a flood control project using a storm water detention pond, designed to allow multiple uses of an urban space. The operation of the system is evaluated by an urban flow-cell model, known as MODCEL. This application seeks the best configuration for the layout of 'Celso Peçanha' Detention Basin, considering the local restrictions imposed by the City of Mesquita - Brazil, and optimized to damp storm flows resulting from rainfall events with return periods up to 50 years. The solution proposed considers the possibility of social urban space uses in flood control projects, revitalizing degraded areas and giving them multiple functions.

Achieving Urban Stormwater Mitigation Goals on Different Land Parcels with a Capacity Trading Approach

Building Green Infrastructures (GIs) to reduce stormwater runoff has been recognized as an effective approach to mitigate the negative impact of urban sprawl. Due to the significant differences in urban land use, some Land Parcels (LPs) may have difficulty in building enough GIs to meet stormwater mitigation goals. In this paper, we proposed a Capacity Trading (CT) approach that allows some LPs to trade their extra runoff retention capacities with LPs that have building difficulties, so that they can jointly reach the overall mitigation goal together. The rationale behind CT is that, to avoid potential penalties, it may be more economical for some LPs to ‘buy’ credit rather than to ‘build’ GIs. A case study was used to demonstrate CT operations for two trading scales: (1) CT within neighboring LPs (i.e., CT-1), and (2) CT within 20 m-radius LPs (i.e., CT-2). A GI implementation baseline intensity was set up firstly by treating the whole study area as one entity to reach a specified stormwater runoff control target; individual LPs were then examined for their GI building capacities, which may be deficit or surplus against the target. Results showed that the number and area of deficit LPs were reduced significantly through either CT scales; the number of deficit LPs was reduced from 139 to 97 with CT-1 and 78 with CT-2, and the deficit area was reduced from 649 ha to 558 with CT-1 and 478 ha with CT-2, respectively. The proposed method assumes LPs as the basic planning unit and encourages some stakeholders to maximize their GI building potential to compensate for those with disadvantages. The economic incentives for conducting CT among different LPs in urban area can help achieve stormwater mitigation goals more economically and flexibly. Some coordination among LPs in GI implementation is necessary, which presents both opportunities and challenges for city management.

The Role of Community Champions in Long-Term Sustainable Urban Water Planning

Community engagement and stewardship are important elements in urban water planning if we are to achieve the vision of water sensitive cities. The aim of this study was to explore how community members could participate in collaborative water planning processes that are adaptive, participatory and transdisciplinary. We conducted a case study of community participation in a water planning process in the regional town of Bendigo in Australia. Over a period of eight months, we worked with key stakeholders to generate integrated, collaborative and people-centred water planning. This involved a series of community champion workshops supplemented by focus groups with additional community members that ran alongside workshops with water and local planning professionals. The goal of the process was to bring together industry, government partners and community members to develop a 50-year vision for a water sensitive Bendigo and to identify the steps needed to achieve this vision. Key findings were that community champions were keen to learn and contribute to urban water planning in their local context. Given time and support, community champions were able to distil complex ideas and make compromises to contribute to a shared vision for the city. Our findings confirm that community champions can play the role of knowledge brokers between water managers and the general population. The research contributes knowledge regarding the value of engaging community champions in urban water planning.

Blue and Green Spaces as Therapeutic Landscapes: Health Effects of Urban Water Canal Areas of Isfahan

Blue and green spaces contribute to the quality of cities in various ways—ranging from providing air corridors and visual amenities to positively affecting public psychological health and wellbeing. Urban blue and green spaces had geopolitical and agricultural functions in the past. These functions are still evident in many cities. They also provide ecological qualities for the surrounding (sub)urban neighborhoods. While in recent decades, many studies have explored the features and characteristics of urban blue and green spaces that are associated with positive health benefits, the healthy lifestyle promoting role of artificial water canals has received little attention. This case report investigates the canals in Isfahan from Iran that branch off from the Zayandeh Rood River and provide blue and green corridors to the city. The aim of this case report study is to explore the health aspects of urban water canals in physical, mental, and social dimensions based on the residents’ experiences. The study develops a framework for assessing the quality of therapeutic effect of canals in Isfahan, Iran. The paper employs qualitative content analysis as the methodological approach. In total, 200 people from the residential neighborhoods of the Niasarm Canal participated in semi-structured interviews in early 2018. The results of this research reveal that the canal—with ‘upgrade of active life’, ‘sense of rehabilitation, relaxation and concentration along with the canal’, ‘promotion of social life’, and ‘place identity’ characteristics—plays an important therapeutic role on the physical, psychological, and social health conditions of local residents.

Towards a New Paradigm of Urban Water Infrastructure: Identifying Goals and Strategies to Support Multi-Benefit Municipal Wastewater Treatment

Over the past decade, water professionals have begun to focus on a new paradigm for urban water systems, which entails the recovery of resources from wastewater, the integration of engineered and natural systems, and coordination among agencies managing different facets of water systems. In the San Francisco Bay Area, planning for nutrient management serves as an exemplary model of this transition. We employed a variety of methodological approaches including stakeholder analysis, multi-criteria decision-making weight elicitation, and document analysis to understand and support decision-making in this context. Based on interviews with 32 stakeholders, we delineate goals that are considered to be important for achieving the new paradigm and we highlight management strategies that can help reach these goals. We identify and analyze the social, institutional, and technical impediments to planning and implementing multi-benefit wastewater infrastructure projects and identify strategies to overcome some of these challenges. Transitioning to a new paradigm for urban water infrastructure will require stakeholders to proactively forge collaborative relationships, jointly define a shared vision and objectives, and build new rules to overcome limitations of current institutional policies.

From conventional drainage to sustainable stormwater management: Beyond the technical challenges

Countries and cities are increasingly recognizing the value of adopting Sustainable Stormwater Management (SSWM) goals and measures. SSWM serves multiple hydrological, ecological, social and economic goals and can replace substantial parts of conventional drainage infrastructure. Following international experience in the socio-technical nature of transitions in stormwater management, this research investigates how socio-institutional factors enable the transition from conventional to sustainable stormwater management over time. The research is based on analysing available relevant documents, semi-structured interviews and focus groups, all in a single country case study (Israel). We found significant changes in professional awareness and discourse, some advances in professional standards of work and changes to the regulative system, supporting infiltration practices in particular. We concluded that the three-pillared socio-institutional framework, composed of cultural-cognitive, normative and regulative changes, was insightful for mapping factors supporting transition from conventional drainage to SSWM. Elements within the three pillars can work simultaneously and synergistically to achieve widespread change. At the same time, while SSWM always strives to achieve multiple goals, the order of priority of the various goals may differ from place to place and may change over time. Thus the transition process across the socio-institutional pillars should be renewed if and when the priority of goals changes. The urban and regional planning system can play a crucial role in enhancing the transition process from conventional to sustainable stormwater management. These conclusions may be relevant to other localities and countries that are struggling with such transitions to sustainability.

Understanding urban water performance at the city-region scale using an urban water metabolism evaluation framework

Water sensitive interventions are being promoted to reduce the adverse impacts of urban development on natural water cycles. However it is currently difficult to know the best strategy for their implementation because current and desired urban water performance is not well quantified. This is particularly at the city-region scale, which is important for strategic urban planning. This work aimed to fill this gap by quantifying the water performance of urban systems within city-regions using 'urban water metabolism' evaluation, to inform decisions about water sensitive interventions. To do this we adapted an existing evaluation framework with new methods. In particular, we used land use data for defining system boundaries, and for estimating natural hydrological flows. The criteria for gauging the water performance were water efficiency (in terms of water extracted externally) and hydrological performance (how much natural hydrological flows have changed relative to a nominated pre-urbanised state). We compared these performance criteria for urban systems within three Australian city-regions (South East Queensland, Melbourne and Perth metropolitan areas), under current conditions, and after implementation of example water sensitive interventions (demand management, rainwater/stormwater harvesting, wastewater recycling and increasing perviousness). The respective water efficiencies were found to be 79, 90 and 133 kL/capita/yr. In relation to hydrological performance, stormwater runoff relative to pre-urbanised flows was of most note, estimated to be 2-, 6- and 3- fold, respectively. The estimated performance benefits from water sensitive interventions suggested different priorities for each region, and that combined implementation of a range of interventions may be necessary to make substantive gains in performance. We concluded that the framework is suited to initial screening of the type and scale of water sensitive interventions needed to achieve desired water performance objectives.

Objectives and Indexes for Implementation of Sponge Cities—A Case Study of Changzhou City, China

This paper presents a framework of objectives and indexes for sponge cities implementation in China. The proposed objectives and indexes aims to reflect whether the city is in accord with the sponge city. Different cities have different objectives and indexes as each city has its own geologic and hydrogeological conditions. Therefore, the main problems (e.g., water security and flood risks) in the central urban area of Changzhou city, China were evaluated scientifically. According to the local conditions, four objectives and eleven indexes have been made as a standard to estimate the sponge city and set a goal for the city development to reach the goal of sustainable urban development. The strategy of process control was implemented to improve the standard of urban drainage and flood control facilities, regulate total runoff and reduce storm peak flow, and the ecological monitoring of the function of the rivers and lakes. The objectives of sponge cities include water security, water quality improvement, healthy water ecosystems, and water utilization efficiency. Urban flood prevention capacity, river and lake water quality compliance, and annual runoff control are the key objectives to encourage the use of non-conventional water resources.