Although urban water management is a relatively young discipline, our impression is that it is rapidly maturing into a rigorous and important topic area. Not only is it attracting greater numbers of young researchers and professionals, but is also opening up new areas beyond those conventionally taught in water engineering. Because of the potential implications of climate change, demographic restructuring, population growth and the need sustainable development, urban water systems are coming more and more ‘centre stage’ in terms of resource recycling, energy efficiency and reduction of the ecological footprint of urban areas, to name just three imperatives. We are seeing conventional systems, such as drinking and wastewater treatment plants, interacting with collection and disposal of stormwater and receiving water bodies being researched from completely new angles. These include long-term effects on water quality and ecological sustainability, prediction of the effects of development scenarios in newly built settlements, including conventional indicators such as cost but also less quantifiable “soft” ones such as suitability and acceptability, carbon demand (“emission efficiency”), ecological affordability and the like. We are convinced that the Urban Water Journal plays an important role in raising awareness and promoting these new concepts.
This issue is a contribution in this direction. The selection of papers that has been made covers both progress in science but also more rigorous methodologies and benchmarking for the growing community of urban water practitioners, which are gradually being “converted” from traditional engineering concepts to more integrated, environmentally aware approaches and concepts.
The paper A suitability evaluation tool for siting wastewater treatment facilities in new urban developments describes the development of a Spatial Decision Support tool based on soft computing that assists the optimal siting of wastewater treatment technologies within the context of new urban developments, through the creation of suitability maps. The tool developed within the project dealing with the issues water for new developments is based on multi-criteria decision analysis and fuzzy logic, allowing the inclusion of both uncertainty and of the decision-makers attitude towards risk in the decision-making process. The paper introduces and discusses the attributes influencing the siting of wastewater treatment infrastructure and presents a method for using them in generating composite siting suitability maps for a given development site. Additionally it proposes specific locations of the plants that will maximise the combined suitability index. Extensive sensitivity analysis has been undertaken and the results discussed.
The next paper Measuring the background concentration in a constructed stormwater treatment wetland describes a study undertaken to determine the background concentration of suspended solids and nutrients in a constructed stormwater treatment wetland. Urban stormwater wetlands have been widely embraced by the community as a beneficial part of the stormwater infrastructure in which the treatment efficiency of wetlands during storm events seems to be well documented, but relatively little is known about inter-event processes, which is subject of the paper. The paper addresses the environmental effects such as wind direction and speed, wildlife and other anthropogenic activities that have a significant impact on these processes. This paper presents the study that creates conditions for the development of a suitable model of these processes, the progress of which is limited by a lack of fundamental data on the movement of contaminants within a stormwater wetland during these inter-event periods. The study has included an intensive monitoring programme of a recently constructed wetland in Brisbane, Australia. The study identified that design issues, such as the characteristics of the inlet structure, play a significant role in the resuspension and movement of suspended solids through the wetland system. Wildlife and anthropogenic activities are also identified as playing an important role during inter-event periods. The distribution and density of vegetation plays an important role in the removal of suspended solids and nutrients within the system during these inter-event periods. The importance of vegetation in the wetland system is also demonstrated by the factors which are commonly in pond systems rather than a constructed wetland.
Thirdly, Experiences with benchmarking of sewerage systems with a special focus on investment costs introduces the essential findings of a recently published report of the project dealing with benchmarking of sewerage systems, with a focus on the analysis of investment costs based on the analysis of 34 sewerage system projects carried out recently in Austria within a benchmarking project. The results are based on an analysis of the final accounts of the finished projects. The paper further delineates the results of the project and considers in detail the important influence of unquantifiable factors, such as economic fluctuations and tendering strategies of the successful contractors, on the calculation of the construction costs. It is believed that similar benchmarking exercise can be performed in other countries based on the approach presented in this paper.
The paper Hydrologic influence on stormwater pollution at two monitoring sites presents the results of investigations into the relationships between the parameters of washoff functions and the controlling hydrological variables affecting pollutant transport from urban paved surfaces. The paper proposes the maximum flow obtained as the average value over the time of concentration of the drainage network to be used as the controlling factor of the total mass of pollutants made available for the wash-off during a runoff event. The results are tested against the data sets obtained during two monitoring campaigns carried out at two different land uses within urban areas.
Finally the paper Surface stormwater hazard assessment in steep urban areas. Case of the city of Mendoza, Argentina is focused on a hazard assessment associated with urban runoff from streets. Two hazard criteria based on a theoretical analysis of the water's force acting on a static pedestrian are presented based on a no-slipping criterion and stability to tilt criterion. According to these criteria, either a maximum depth, or a maximum velocity or some combination of depths and velocities, should be fulfilled in order to guarantee pedestrians' and drivers' safety in the case of medium to large storms. A one-dimensional numerical urban storm runoff model is applied to an urban watershed of the city of Mendoza to obtain the runoff values for various return periods. The model is shown to be a useful tool in relation to the application of the hazards criteria.
We would like to use this opportunity to thank Dr Shuming Lui for his professional efforts and reliability while assisting us in editing the Journal over the past year or so and wish him every success in his new position at Tsinghua University in Beijing, PR China. In turn we would also like to introduce our new assistant in the Editorial office Mrs Alix Slater.