Stormwater Source Control Research Articles

Climate Change Impacts on Water Sensitive Urban Design Technologies

Water Sensitive Urban Design (WSUD) technologies are green infrastructures that aim to restore the hydrological balance of urban catchments. This research aimed to investigate the impacts of climate change in an infiltration-based WUSD, called soak-away, at residential allotments from a Village Green townhouse complex, Aldinga, South Australia. To do so, specific rainfall data for the study area were collected and then projected for the years 2030, 2060 and 2090, considering the RCP 4.5 and 8.5 pathways. The projections were determined using CSIRO’s Climate Futures tool, as suggested in the Australia Rainfall Runoff guidelines. The rainfall’s projected impacts on the soak-away performance and dimensions were analyzed in terms of the Village Green catchment conditions, using the MUSIC model and stormwater source control principles. When analyzing the RCP 8.5 pathway for different years, the distinction in soak-away design was more evident and was directly related to the peak flow percentage of the increase obtained in the MUSIC model. On the other hand, for RCP 4.5, the years 2030 and 2060 presented the same characteristics, and 2090 had an equivalent rainfall projection as RCP 8.5 2030. Regarding treatment effectiveness, the soak-away dimensions reached almost 100% of pollutant removal, which indicates that the approach might oversize the system. Nonetheless, when comparing all soak-away designs, the recommended soak-away system tends to be conservative due to the uncertainties surrounding future climate projections.

A closed-loop analysis approach for ensuring stormwater source control design solution to achieve the intended goals

Stormwater source controls have been adopted worldwide to address hydrological and environmental impairments caused by the spread of impervious surfaces in cities. Current design method in China uses 30-year daily rainfall records to generate relationship of rainfall volume capture ratio (αg) and daily design storm, and then uses design storm to propose design solution. However, source control performance differs from rain to rain, and hence the design solution's actual effect may deviate from αg. Borrowing closed-loop feedback concept from business domain, this study proposes closed-loop analysis (CLA) which uses design solution's 30-year simulated result as data feedback to check design solution's effectiveness and then make improvements if necessary. It consists of four methods: 1) hourly design storm statistical method, for addressing the weakness of current daily design storm; 2) design solution model credibility examination method, for guaranteeing credibility of 30-year simulated results for CLA; 3) appropriate design storms determination method for source control without underdrain; 4) additional design parameters optimization method for source control with underdrain. Taking Xiamen city for example, case study results shows that design solution's 30-year simulated results were consistent/comparable with sizing calculation formula that was used to propose design solution, and therefore they were credible for CLA. Appropriate design storms ensured design solutions without underdrain to achieve the intended αg±3 %. Optimal design parameters combinations ensured design solutions with underdrain to achieve αg but also restore natural runoff events with pre- and post-development runoff frequency spectra similarity being 0.670–0.691. Based on stormwater mathematical model, CLA can drive source control design computation to a new methodological stage.

Stormwater Gravel-Peat Infiltration Filter – An Ecohydrological Technology with Good Urban Design

Urban stormwater flooding and pollution are severe issues due to connected impervious surfaces. Over recent decades, solutions to these issues have been towards stormwater source control measures. We developed an innovative cost-efficient stormwater infiltration filter, made of gravel-peat mixture and geotextile. Laboratory column tests were conducted to compare a range of volumetric ratios of gravel (limestone and silica) to peat regarding their heavy metal removal efficiency (RE). The tested heavy metals were cadmium, lead and zinc. All ratios had a high RE (95.9%-100%), despite very high initial metal concentrations. The 5LG:1P mixture (i.e., volumetric ratio of limestone gravel to peat was 5:1) had the highest RE (99.6%-100%) and is suggested as a good candidate for implementation. If a longer-term use is required, a 5SG:10LG:3P mixture (i.e., volumetric ratio of silica gravel, limestone gravel, and peat of 5:10:3) is recommended as it kept the high heavy metal RE with a lower clogging potential and lower cost than the 5LG:1P mixture. The most convenient but expensive filter material with high RE is limestone gravel alone. Finally, we proposed two field designs for implementing the infiltration filter, which incorporate concepts of “treatment train” and “good urban design”. We also provided some suggestions for the installation of gravel-peat infiltration filters.

Cost-benefit analysis of low-impact development at hectare scale for urban stormwater source control in response to anticipated climatic change

Investigation of the cost-effectiveness of low-impact development (LID) practices at the hectare scale in response to impacts of possible climate change was conducted using representative concentration pathways (RCPs). An LID project in Guangzhou has been selected to illustrate changes in the hydrologic performance for alternative source control strategies for a variety of future climate models and scenarios. Frequent storms of shorter duration in RCP 8.5 cause more dramatic fluctuation of hydrologic performance. Hydrologic performance of LID practices on reducing runoff volume and peak flow in test catchment are different in climate scenarios. Based on the constraints of life cycle costs and environmental impacts of LID alternatives, comprehensive strategies were found effective in managing surface runoff at the source to adapt to the influence of climate change. The methodology described herein could be useful in considering LID practices for critical source management with limited budgets and considering environmental impacts under long-term climate change.

Role of Low-Impact Development in Generation and Control of Urban Diffuse Pollution in a Pilot Sponge City: A Paired-Catchment Study

Low-impact development (LID) is increasingly recognized as one of the most important stormwater source controls on a small scale. However, few studies have reported how LID practices affect the generation and control of urban diffuse pollution at the scale of urban drainage units. In this study, paired conventional and LID drainage units (CDU and LDU) were used to distinguish the role of LID practices in urban sediment accumulation and release at a residential drainage units scale (about 1–2 ha). The urban sediment dynamic build-up process, amounts per unit to equilibrium, amount and percentage of urban sediment washed-off by rainfall, pollutant concentrations during rainfall-runoff processes, and discharge water volume and pollution load from drainage units were all notably different between the paired drainage units. These results indicated that (1) LID practices have a combined effect on urban sediments accumulation and release on a drainage unit scale via reduction of the source area, changes in microtopography and formation of a greater sink area; (2) landscape alterations with LID practices within a small catchment reduced and disconnected areas with impervious surfaces, subsequently reducing the kinetic energy of wash-off and transport for urban sediment; (3) LID practices exerted notable hydrological responses and water quality responses at a micro urban catchment scale by reducing the first flush load and entire process discharge load. The results presented herein will facilitate optimal design for reliable treatment performance and assessment of the effectiveness of LID practices on an urban drainage units scale.

Challenges in implementing integrated catchment management and sustainable stormwater solutions in Bangkok, Thailand

Abstract By reviewing related studies, published journal articles, research and government reports, this study explored the challenges in water governance, focused on the planning for integrated catchment management (ICM) and stormwater source control (SC) in Bangkok and its catchment. The review revealed implementation barriers, and eight categories of challenge: fragmented roles and responsibilities; technocratic bureaucracy; limitations of the regulatory framework; financial barriers; physical barriers; challenges of integrated knowledge; an uncoordinated institutional framework; and limited community and stakeholder involvement. The understanding of barriers to ICM planning and SC approaches is crucial for developing strategies that diminish barriers and increase the implementation of alternative solutions.

Assessing the Effect of Uncertainties in Pollutant Wash-Off Dynamics in Stormwater Source-Control Systems Modeling: Consequences of Using an Inappropriate Error Model

This study investigates the effect of uncertainties associated with pollutant wash-off dynamics in the context of stormwater management practices modelling. A formal Bayesian approach is adopted for the calibration and the uncertainty analysis of a commonly used wash-off model, under (1) the unverified assumption of homoscedastic, independent and normally distributed residuals and (2) using a more correct heteroscedastic and autoregressive error model. The results obtained for each of these approaches are compared and the uncertainty associated with water quality modelling is later propagated through a conceptual Best Management Practices (BMP) model, for various stormwater management scenarios, so as to assess the effect of this uncertainty for BMP modelling and clarify the benefits of a robust description of error structure. This study indicates that the violation of the statistical asumptions about the residuals may result in unreliable estimation of model parameters and total predictive uncertainty. The effect of the uncertainty in the intra-event variability of concentations in runoff is however found to have only a limited effect on the outputs of the BMP model, regadless of the error model adopted for calibration.

Identifying keystone meteorological factors of green-roof stormwater retention to inform design and planning

Green roofs have received considerable attention for multiple ecosystem services which include stormwater amelioration. Offering sustainable stormwater source-control, green roofs utilize otherwise unused impervious urban surfaces to restore pre-development hydrologic functions such as infiltration and retention. Its ability to retain stormwater is related to external and internal factors. Meteorological conditions prior to a rainfall event can influence antecedent evapotranspiration, the only water-exit pathway of the green-roof system besides discharge. Whereas evapotranspiration may be difficult and costly to measure directly, other common meteorological conditions can be monitored conveniently and inexpensively even prior to actual green-roof installation. Identifying salient on-site meteorological factors may provide valuable insights into hydrologic dynamics, and inform green-roof design and planning decisions. A statistical regression approach identified potential antecedent meteorological factors and moisture indicators of extensive green-roof retention. Continuous field-monitoring data revealed the combined effects of rainfall depth, wind speed, solar radiation, and antecedent dry weather period to explain the measured stormwater retention under a humid subtropical rainfall regime. Amongst the studied environmental factors, solar radiation and wind speed contributed notably to green-roof stormwater retention and may provide a dependable basis to assist green-roof site selection when resources are limited. It is important to incorporate site-specific planning and assessment prior to green infrastructure design and implementation to maximize hydrologic and evaporative cooling services in cities with complex topographical features.

A simple model of flow-rate attenuation in sewer systems. Application to urban stormwater source control

In urban stormwater management, ''soft'' solutions are being widely applied, including stormwater source control. However, no specific resource-effective model is available to assess their effects at the city-scale. As a consequence, source control regulations are often based on simplistic hydrologic assumptions. In this paper, we apply a top-down modeling approach to this problem, and we develop a simple model of flow-rate attenuation in the sewer system, using a numerical empirical approach. Then, we apply the model to source control regulations, assessing which type of regulation is more effective depending on relative positions in a catchment. We show that a model requiring only two types of information about a catchment (concentration time and pluviometry) can provide relevant information on source control effectiveness. This information could be helpful, for example, to define a stormwater zoning.

Urban stormwater source control policies: why and how?

Abstract. Stormwater source control is becoming a common strategy for urban stormwater management in many countries. It relies on regulations or other policy instruments compelling or inciting implementation, for each new urban development, of small-scale facilities to locally store and manage stormwater. Local authorities that pioneered source control since the 1980s have already observed that small-scale facilities systematically implemented over a catchment are able to influence its hydrological behaviour. This capability is the main strength of source control, as it allows compensation for the negative effects of urbanization. Yet, it also represents its main risk: if initial decision-making is not sufficiently accurate, source control can produce long-term negative effects. Because of its current spreading, source control will acquire an increasing role as a driver of hydrological changes in urban catchments, and the directions of these changes depend on current policy-making practices. This paper presents an analysis and a critical discussion of the main objectives that policy-makers attribute to stormwater source control. The investigation is based on a sample of French case studies, completed by a literature review for international comparison. It identifies four main objectives, some typical of urban stormwater management and some more innovative: flood reduction, receiving waters protection, sustainable development, costs reduction. The discussion focuses on how current policy-making practices are able to translate these objectives in concrete policy instruments, and on which knowledge and tools could improve this process. It is shown that for some objectives, basic knowledge is available, but the creation of policy instruments which are effective at the catchment scale and adapted to local conditions is still problematic. For other objectives, substantial lacks of knowledge exist, casting doubts on long-term effectiveness of current policy instruments. Research directions are identified to improve source control policies and thus the future hydrologic behaviour of many urban catchments.

The impact of stormwater source-control strategies on the (low) flow regime of urban catchments

Stormwater management strategies increasingly recognise the need to emulate the pre-development flow regime, in addition to reducing pollutant concentrations and loads. However, it is unclear whether current design approaches for stormwater source-control techniques are effective in restoring the whole flow regime, and in particular low flows, towards their pre-development levels. We therefore modelled and compared a range of source-control stormwater management strategies, including some specifically tailored towards enhancing baseflow processes. The strategies were assessed based on the total streamflow volume and three low flow metrics. Strategies based on harvesting tanks showed much greater volume reduction than those based on raingardens. Strategies based on a low flow rate release, aimed at mimicking natural baseflow, failed to completely restore the baseflow regime. We also found that the sensitivity of the low flow metrics to the proportion of catchment treated varied amongst metrics, illustrating the importance of metrics selection in the assessment of stormwater strategies. In practice, our results suggest that realistic scenarios using low flow release from source-control techniques may not be able to fully restore the low flow regime, at least for perennial streams. However, a combination of feasibly-sized tanks and raingardens is likely to restore the baseflow regime to a great extent, while also benefitting water quality through the retention and filtration processes.

Modelling the impact of stormwater source control infiltration techniques on catchment baseflow

AbstractStormwater management increasingly recognises the need to emulate, to the maximum extent possible, the flow regime of receiving waters in their pre‐development state. Hydrological models play a central role in assessing the catchment‐scale impacts of alternative stormwater management strategies. However, because of the complexity of physical processes involved in urban hydrology, particularly subsurface flows, the predictive performance of such models is often low. We investigated how the structure of hydrological models influenced the prediction of urbanisation and stormwater management impacts on baseflow. We calibrated three conceptual models of the same reference catchment and compared the modelled flow regime from different stormwater management scenarios, using each of the three model structures. Scenarios were assessed using six metrics, characterising the whole streamflow regime and in particular baseflow. Although the three models of the reference catchment represented the observed hydrograph well, the most complex structure developed using a thorough diagnostic of the catchment behaviour better captured the change in hydrological regime during dry years. Predictions of baseflow changes due to urbanisation varied significantly according to the model structure. Similarly, the models showed distinct responses to the stormwater management scenarios applied, especially for scenarios involving infiltration of stormwater at source. Our results confirm the importance of predicting the consequences of land use changes with conceptual models that are consistent with the hydrological behaviour of the study catchment. Future work should help to quantify the uncertainties due to model structure and thus provide practical guidance to the use of catchment models for assessing stormwater management strategies. Copyright © 2013 John Wiley & Sons, Ltd.

DayWater: an Adaptive Decision Support System for Urban Stormwater Management

The European DayWater project has developed a prototype of an Adaptive Decision Support System (ADSS) related to urban stormwater pollution source control. The DayWater ADSS greatly facilitates decision-making for stormwater source control, which is currently impeded by the large number of stakeholders involved and by the necessary multidisciplinary knowledge. This book presents the results of this project, providing new insights into both technical and management issues. The main objectives of its technical chapters are pollution source control modelling, risk and impact assessment, and evaluation and comparison of best management practices. It also covers management aspects, such as the analysis of the decision-making processes in stormwater source control, at a European scale, and stormwater management strategies in general. The combination of scientific-technical and socio-managerial knowledge, with the strong cooperation of numerous end-users, reflects the innovative character of this book which includes actual applications of the ADSS prototype in significant case studies. DayWater: an Adaptive Decision Support System for Urban Stormwater Management contains 26 chapters collectively prepared by DayWater scientific partners and end-users associated with this European Research and Development project. It includes: * A general presentation of the DayWater Adaptive Decision Support System (ADSS) structure and operation modes, * A detailed description of the major components of this ADSS prototype, * The assessment of its components in significant case studies in France, Germany and Sweden, * The proceedings of the International Conference on Decision Support Systems for Integrated Urban Water Management, held in Paris on 3-4 November 2005. The book presents the ADSS prototype including a combination of freely accessible on-line databases, guidance documents, road maps and modelling or multi-criteria analysis tools. As demonstrated in several significant case studies the challenge for stormwater managers is to make the benefits of urban stormwater management visible to society, resulting in active co-operation of a diversity of stakeholders. Only then, will sustainable management succeed. DayWater: an Adaptive Decision Support System for Urban Stormwater Management advances this cause of sustainable urban management through Urban stormwater management, and makes achievable (by means of risk and vulnerability tools which are included) the goal of integrated urban water management (IUWM).

Do stormwater source control policies deliver the right hydrologic outcomes?

Summary The number of stormwater source control (SC) regulations adopted by local authorities is rapidly growing in many countries. We can expect that, in the near future, the hydrologic behavior of many urban and periurban catchments will reflect this diffusion. This paper discusses SC regulations through two complementary approaches: starting on three French case-studies, it analyzes how regulations are developed today and identifies a set of shortcuts in policy-making practices. Then, the hydrologic model of a periurban catchment in the Paris region is used to test the impacts that these regulations can produce if widely applied. The main finding is that inertia in policy-making, driving a singular focus on flow-rate based regulations, can produce negative impacts in the long-term. Further efforts on volume-based regulations are advocated, both in terms of research and policy-making.

Rainwater harvesting to control stormwater runoff in suburban areas. An experimental case-study

On a 23 ha urban watershed, 10 km East of Paris, rainwater tanks have been installed on 1/3 of the private parcels to prevent stormwater sewer overflows. This paper investigates the macroscopic effect of rainwater harvesting on runoff, and thus the potential of this technique for stormwater source control. The analysis is performed using the SWMM 5 model, calibrated on rainfall- runoff measures from two measurement campaigns, before and after the equipment. The availability of two data-sets allows the authors to point out changes in the catchment's behaviour. The main findings are that: (1) catchment's evolution, mainly caused by individual land-cover modifications, produces non-stationarity of the hydrologic behaviour; (2) the rainwater tanks installed, although they affect the catchment hydrology for usual rain events, are too small and too few to prevent sewer overflows in the case of heavy rain events.

Monitoring and Modeling the Effects of Stormwater Source Controls on Sediment Quality in Tacoma, Washington

Monitoring and Modeling the Effects of Stormwater Source Controls on Sediment Quality in Tacoma, WashingtonFollowing the successful Superfund sediment remediation in the Thea Foss Waterway (2006), the City of Tacoma manages sediment recontamination along its downtown waterfront using a multi-faceted program which includes sediment/stormwater monitoring; an EPA-supported sediment recontamination model (Water Quality Analysis Simulation Program); source control; and a GIS-based pollutant loading model...Author(s)Dana B. de LeonMary L. HenleyTodd M. ThornburgSourceProceedings of the Water Environment FederationSubjectSession 19: Water Quality and Watershed ModelingDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2011ISSN1938-6478SICI1938-6478(20110101)2011:17L.978;1-DOI10.2175/193864711802639552Volume / Issue2011 / 17Content sourceWEFTECFirst / last page(s)978 - 997Copyright2011Word count164Subject keywordsstormwatersource controlstormwater maintenanceNPDESHSPF modelWASP modelstormwater monitoringsedimentrecontaminationSuperfund

The potential of green roofs to manage Urban Stormwater

Green roofs have considerable potential for stormwater source control, both for new developments and as a retrofit option. In the United Kingdom the lack of local quantitative performance data and modelling tools, together with more general barriers to sustainable drainage systems (SUDS) implementation, may explain their limited uptake to date. This paper presents preliminary findings from a small-scale instrumented green roof test plot located in Sheffield, UK. During spring 2006 the average volume retention was 34% and the average peak reduction was 57%. The key hydrological determinants were the antecedent dry weather period (ADWP), mean rainfall intensity and rainfall depth. Detailed examination of rainfall–runoff relationships in summer 2007 demonstrates the dependency of performance on antecedent moisture conditions. Structural appraisal of a range of flat roof types suggests that retrofitting a green roof will be a feasible option in many cases, particularly for concrete slab roofs.

Urban stormwater drainage management: The development of a multicriteria decision aid approach for best management practices

Multicriteria analysis methods have been used over the past decade for resolving environmental issues. This paper deals with the application of a multicriteria analysis (MCA) approach to urban stormwater drainage management. Stormwater source control has become a popular alternative solution for managing stormwater in urban areas. Source control constitutes one variant of best management practices (BMPs) that can be evaluated with respect to various criteria, including: hydraulic efficiency, pollution retention, environmental impact, operation and maintenance, economic investment, and social and sustainable urban living. A French survey was undertaken to assess the performance of different BMPs at the national scale; results highlight the main reasons justifying the use of BMPs. These reasons are primarily related to flood prevention, which far outweighs the economic incentives. Moreover, hydraulic and technical aspects are most frequently noted by users, whereas operation and maintenance aspects are often seen as obstacles to application of these techniques. The survey results, completed by a literature review and expert statements, have been used to establish a matrix of alternatives for multicriteria analysis. The MCA results obtained allow ranking the various alternatives from best to worst, taking into account the different strategies adopted by the decision-makers involved. The development of a multicriteria approach could, in the future, serve as a supporting decision-aid tool, whose purpose would be to guide users in their choice of stormwater source solution.

Applying storm water management in Greek cities: learning from the European experience

This paper is based on the studies forming part of the European research project DayWater, which aims at the promotion of stormwater source control (participating countries: UK, France, Sweden, Denmark, Germany, The Netherlands and Greece). Source control techniques include all techniques (e.g. retention, infiltration, reuse) of stormwater treatment near its source, in contrast to end-of-pipe. In this paper we present: the different stormwater management issues across Europe; the specific stormwater management issues in Greece; source control techniques applied in European cities; Public policies for promoting source control techniques; Strategies of application of the aforementioned techniques and policies in Greek cities. In Greece, the question of stormwater treatment has not yet attracted a lot of attention. Wastewater management, flood prevention and fresh water scarcity issues are given priority instead. However source control stormwater management can contribute to the solution of all these problems. In many European cities source control techniques have been chosen for stormwater treatment because: a) they are less expensive than massive end-of-pipe treatment installations, b) they are more compatible with the natural water cycle, c) they reduce the overall stormwater flow and thus permit the expansion of cities without requesting reconstruction of the existing sewer networks. Different policy instruments (taxes, specific regulations and controls, information campaigns) have been applied in order to promote source control techniques. The main objective of this work is to discuss the possibility of applying similar techniques and policies in Greek cities.

The Role of Water Balance Modelling in the Transition to Low Impact Development

Abstract Low impact development (LID) is increasingly being viewed by local governments and developers alike as a viable approach to stormwater management that can effectively protect aquatic habitat and water quality. LID relies on distributed runoff management measures that seek to control stormwater volume at the source by reducing imperviousness and retaining, infiltrating and reusing rainwater at the development site. Early conventional stormwater management practices tended to focus on stormwater quantity and controlling a few extreme rainfall events, whereas the more frequent storms, which represent the majority of total runoff volume, carry most of the pollutants, and control the geomorphology of streams, were addressed in stormwater quality design practiced during the last decade. These frequent events are most effectively managed with a volume control approach, often described as stormwater source control or Low impact development (LID). Such an approach is described in this paper, demonstrating how water balance modelling can be an effective tool for evaluating and supporting implementation of LID options such as bioretention, pervious paving, numerous types of infiltration systems, rainwater reuse and green roofs. It also discusses recently developed water balance modelling software, including an Internet-based planning tool and a design optimization tool.