This study focuses on characterising stormwater in order to be able to determine the impact of stormwater on receiving waters and to be able to select the most appropriate stormwater handling strategy
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A baseline study was performed to characterize the stormwater quality from the upstream roofs and road areas. Results showed variations in stormwater quality. This may inhibit single-step treatment performance. Therefore, a ‘treatment train’ of several SUDS measures was developed in order to achieve high pollutionremoval rates and to help prevent loss of valuable archaeological deposits and thereby reduce subsidence.
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Stormwaters, flowing into storm sewers, are known to significantly increase the annual pollutant loads entering urban receiving waters and this results in significant degradation of the receiving water quality. Knowledge of the characteristics of stormwater pollution enables urban planners to incorporate the most appropriate stormwater management strategies to mitigate the effects of stormwater pollution on downstream receiving waters. This requires detailed information on stormwater quality, such as pollutant types, sediment particle size distributions, and how soluble pollutants and heavy metals attach themselves to sediment particles. This study monitored stormwater pollution levels at over 150 locations throughout the Netherlands. The monitoring has been ongoing for nearly 15 years and a total of 7,652 individual events have been monitored to date. This makes the database the largest stormwater quality database in Europe. The study compared the results to those presented in contemporary international stormwater quality research literature. The study found that the pollution levels at many of the Dutch test sites did not meet the requirements of the European Water Framework Directive (WFD) and Dutch Water Quality Standards. Results of the study are presented and recommendations are made on how to improve water quality with the implementation of Sustainable Urban Drainage Systems (SUDS) devices.
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In 2024 the Low Impact Development Devices (LID) open-source international database ClimateScan consist of over 14.000 climate adaption related projects uploaded in the period of 2014–2024. For cities with over 500 projects, this offers an opportunity to construct a LID-DNA of the city. LID-DNA presents the ‘genetic information of the development and functioning of LID in a city’ and was first used in The Netherlands during ClimateCafés as evaluation for future design and maintenance of stormwater management strategies. The LID-DNA of several cities based on the quantity and categories of LID is visualized. The LID structure of early adaptor Amsterdam with over 500 LID measures implemented in 2000–2024, shows a large variety of over 20 types of individual LID. The relative new adaptor Riga shows a LID-DNA with a focus on bio-filtration with raingardens and swales (based on 40 data points). Stakeholders from different departments concluded that cities benefit from the insights of their urban LID-DNA earlier in the process. An early insight will support a targeted LID strategy choosing a limited cost-efficient group of LID than having a wide range of different LID without evaluation of their efficiency. Departments in the city asked for more detailed insights (earlier in the process) to prevent mal-adaptation and disinvestments and be more efficient with their capacity. The ClimateScan database holds over 300 monitored LID projects with research results in North America and Europe in cities as Vancouver, New Orleans, Amsterdam and Riga. Future work will focus on more detailed LID-DNA visualisation based on not only the amount of LID but on the dimensions such as water storage (m 3 ) and surface (m 2 ). Monitoring of LID will be stimulated to make strategic decisions on measured infiltration rates (m/d) of LID as most important criteria for possible damage by floodings and maintenance (clogging). Raising awareness and capacity building targeted on the high-ranking cost-efficient LID is set up in both cities focused on the design, construction and maintenance of LID.
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Storm sewers are known to significantly contribute to annual pollutant loads to receiving water bodies. The storm sewers of the city of Almere discharge the stormwater of 1384 ha of impervious area via 700 storm sewer outfalls (SSOs) to the local receiving water system. This water system suffers from eutrophication and long term build-up of pollutant levels in the sediment bed. In order to be able to select the most effective stormwater management strategy, the municipality of Almere and Water Authority Zuiderzeeland have launched a 2 year extensive monitoring project to measure the stormwater quality and the potential impact of source control and end of pipe measures to decrease the emission via SSOs. Source control measures, such as removal of illicit connections and increasing the cleaning frequency of gully pots showed to be most effective. The potential impact of end of pipesolutions based on settling showed to be very limited due to the low settleability of solids in the storm water of Almere at the SSOs.
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SummaryConstructed wetlands have been used for decades on industrial areas to treat stormwater. European regulations and local ambitions for water quality dictate lower emissions before the water is discharged to the drainage system, surface water or infiltrated to ground water. The increase in the required removal efficiency requires a better understanding of the characteristics of pollutants and cost-effective performance of constructed wetlands. In this chapter detailed characteristics of stormwater from (industrial) areas is given together with monitored removal efficiencies and the cost of constructed wetlands. Some case studies with constructed wetlands are selected and reviewed in this chapter which can be regarded as Best Management Practices (BMPs). In most cases the constructed wetlands are not monitored in detail but perceived to be effective. Long-term performance, however, remains an issue. New monitoring techniques such as underwater drones and full scale testing can be applied to get new insights on optimizing the hydraulic capacity and removal efficiency of wetlands. Last but not least: international knowledge exchange on constructed wetlands and new monitoring techniques can be promoted by interactive online tools.
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Constructed wetlands are one type of Sustainable Urban Drainage System (SUDS) that have been used for decades in The Netherlands. They provide stormwater conveyance and improve stormwater quality. European regulations for water quality dictate lower and lower concentrations for an array of dissolved pollutants. The increase in the required removal efficiency for these systems imposed in the Netherlands requires a better understanding of thecharacteristics of stormwater and the functioning of constructed wetlands as SUDs. This paper presents a brief overview of 5 different constructed wetlands from the Netherlands that have been implemented at least more than 10 years ago. Their efficiency and functioning is reviewed and a new method of assessment is described.
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Urbanisation and climate change have an effect on the water balance in our cities resulting in challenges as flooding, droughts and heatstress. Implementation of Sustainable Urban Drainage Systems (SuDS) can help to restore the water balance in cities by storing and infiltrating stormwater into the subsurface to minimise flooding, restoration of groundwater tables to prevent droughts, lowering temperatures by evapotranspiration to fight heatstress. Urban planners and otherstakeholders in municipalities and water authorities struggle with implementing SuDS at locations where infiltration of water seems challenging. Questions arise as: can you infiltrate in countries as The Netherlands with parts under sea level, high groundwater table and low permeable soil? Can you infiltrate in Norway with low permeable or impermeable bedrock and frozen ground most of theyear? How do you find space to implement SuDS in the dense urban areas of Bucharest? These questions are answered by researchers of the JPI Water funded project INovations for eXtreme Climatic Events (INXCES).To answer the question on ‘can we infiltrate stormwater under worse case conditions?’, testing of the hydraulic capacity take place at rainwater gardens in Norway (Bergen and Trondheim) and (bio)swales in the low lying parts of The Netherlands. The first results show that even under these ‘extreme’ hydraulic circumstances the hydraulic capacity (or empty time) is sufficient to infiltratemost of the stormwater throughout the year.INXCES exchanged researchers on an international level, shared research results with stakeholders and sets up guidelines for design, implementation and maintenance of SuDS to promote the implementation of sustainable water management systems throughout the world.One of the tools used to promote SuDS is www.climatescan.nl, an open source online map application that provides an easy-to-access database of international project information in the field of urban resilience and climate adaptation. The tool is able to map several sustainable urban drainage systems as has been done for Norway, The Netherlands, Romania and other countries in the world.The tool is used for engagement with stakeholders within EU projects as INXCES and WaterCoG and resulted in international knowledge exchange on infiltration of stormwater under extreme climate and geohydrolic circumstances.
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Sedimentation devices have been widely implemented to remove suspended solids and attached pollutants from stormwater before entering surface waters. The treatment performance of these best management practices (BMPs) on fine particles is rarely investigated in a standardized way. To overcome this information gap a reliable and standardized testing procedure is formulated.Four devices have been tested on their suspended sediments removal efficiency at different discharges and particle sizes, using the newly developed standardized full scale test method. The observed removal rates of the facilities with a storage volume in the order of 1.5 m3 and settling surface around 1 m2 drop to low removal efficiencies at flow rates of 10 l/s or more. For small sized sediments (up to 63 μm) the removal efficiency is below 50%. The results of the experiments can be used to improve both the design and the dimensions of stormwater treatment devices.
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Met de toenemende drukte in de stad neemt ook het autogebruik toe. Deze toename zorgt voor extra druk op de veiligheid en gezondheid voor mens en natuur. Om de negatieve impact van verkeer te mitigeren kan gekeken worden naar strengere eisen aan hinder en uitstoot. Met Smooth Traffic Management (STM) wordt gewerkt aan het verminderen van de negatieve verkeerseffecten rond ‘gevoelige locaties’ door bestuurders middels een navigatiesysteem een alternatieve, omgevingsbewuste route aan te bieden.
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