Although permeable pavements have been used all over the world in recent years to infiltrate and treat stormwater, only limited research has been undertaken to investigate and compare the long-term performance of these sustainable urban drainage system devices. This paper presents the results of an extensive international review of research on the reduction of infiltration capacity of permeable pavements over time. The results of these studies, coupled with specific knowledge of the key environmental factors on the individual research locations and infiltration testing methods used, enables the maintenance of these SUDS to be strategically planned in order to meet specific European and international infiltration capacity guidelines.
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Permeable pavements are a type of sustainable urban drainage system (SUDS)technique that are used around the world to infiltrate and treat urban Stormwater runoff and to minimize runoff volumes. Urban stormwater runoff contains significant concentrations of suspended sediments that can cause clogging and reduce the infiltration capacity and effectiveness of permeable pavements. It is important for stormwater managers to be able to determine when the level of clogging has reached an unacceptable level, so that they can schedule maintenance or replacement activities as required. Newly-installed permeable pavements in the Netherlands must demonstrate a minimum infiltration capacity of 194 mm/h (540 l/s/ha). Other commonly used permeable pavement guidelines in the Netherlands recommend that maintenance is undertaken on permeable pavements when the infiltration falls below 0.50 m/d (20.8 mm/h). This study used a newly-developed, full-scale infiltrationtest procedure to evaluate the infiltration performance of eight permeable pavements in five municipalities that had been in service for over seven years in the Netherlands. The determined infiltration capacities vary between 29 and 342 mm/h. Two of the eight pavements show an infiltration capacity higher than 194 mm/h, and all infiltration capacities are higher than 20.8 mm/h. According to the guidelines, this suggests that none of the pavements tested in this study would require immediate maintenance.
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This research used a newly developed, full-scale infiltration testing (FSIT) procedure to determine the saturated surface infiltration rate of 16 existing permeable pavement installations in the Netherlands that have been in service for a number of years. Newly installed permeable pavements in the Netherlands must demonstrate a minimum infiltration capacity of 194 mm/h (540 L/s/ha). Only four of the 16 pavements tested in this study had an infiltration capacity higher than 194 mm/h. Most previous research has focused on unsaturated infiltration rates. However, the results of this study show that the difference in infiltration capacity between saturated and unsaturated can differ by up to 300%. If the unsaturated infiltration capacity is used as design input for computer models, the infiltration capacity may be significantly overestimated. The study demonstrated that the FSIT method is a reliable and accurate way to measure surface infiltration rates of permeable pavements. However, it is recommended that a minimum of three different FSIT tests should be undertaken at the same pavement location, and that the results should be averaged, to ensure appropriate infiltration rates are observed, recorded, and used in design. The results of this study should help stormwater managers with the planning, testing, and scheduling of maintenance requirements for permeable pavements with more confidence so that they will continue to perform satisfactorily over their intended design life
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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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Permeable pavements are a type of SUDS that are becoming more common to allow infiltration, to minimize runoff volumes and to treat urban water stormwater by soil filtration. However, urban stormwater runoff contains significant concentrations of suspended sediments that can cause clogging and reduce the infiltration capacity and effectiveness of permeable pavements. This study used a full-scale infiltration test procedure to evaluate the infiltration performance of 20 permeable pavements that have been in service for over 2 to 9 years in the Netherlands. The observed infiltration capacities range between 20 and 342 mm/h.
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Swales are widely used Sustainable Urban Drainage Systems (SuDS) that can reduce peak flow, collect and retain water and improve groundwater recharge. Most previous research has focused on the unsaturated infiltration rates of swales without considering the variation in infiltration rates under extreme climate events, such as multiple stormwater events after a long drought period. Therefore, fieldwork was carried out to collect hydraulic data of three swales under drought conditions followed by high precipitation. For this simulation, a new full-scale infiltration method was used to simulate five rainfall events filling up the total storage volume of the swales under drought conditions. The results were then compared to earlier research under regular circumstances. The results of this study show that three swales situated in the same street show a variation in initial infiltration capacity of 1.6 to 11.9 m/d and show higher infiltration rates under drought conditions. The saturated infiltration rate is up to a factor 4 lower than the initial unsaturated rate with a minimal rate of 0.5 m/d, close to the minimum required infiltration rate. Significant spatial and time variable infiltration rates are also found at similar research locations with multiple green infrastructures in close range. If the unsaturated infiltration capacity is used as the design input for computer models, the infiltration capacity may be significantly overestimated. The innovative method and the results of this study should help stormwater managers to test, model, plan and schedule maintenance requirements with more confidence, so that they will continue to perform satisfactorily over their intended design lifespan.
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Over the past decades, various types of permeable pavements have been implemented in different municipalities in the Netherlands in order to improve infiltration capacity in urban areas and therewith being able to better treat stormwater runoff. With initial promising results, this adaptation measure seemed to be the solution for urban flooding due to extreme precipitation.However, in practice, foreseen infiltration capacities were usually not met, often due to unknown reasons. To better understand the functioning of permeable pavements in practice, we have studied - as part of the project Infiltrating Cities - over 100 existing permeable pavement installations in the Netherlands. At each location, infiltration capacity was tested through a full-scale infiltration testing procedure (flooded area about 40 m2) while conditional on-site factors were collected (location, age, type of permeable pavement, street-type, traffic density, vicinity of urban green, regular maintenance regime, etc.). By coupling this information we analyzed how these factors influence the infiltration capacity of permeable pavements in practice, e.g. through accelerated deterioration of infiltration capacity through time. In addition, we evaluated for a selected number of installations, how various types of maintenance may counteract this deterioration, hence improving the infiltration capacity of permeable pavements.
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Permeable pavements are specifically designed to promote the infiltration of stormwater through the paving surface in order to reduce run-off volumes and to improve water quality by removing sediment and other pollutants. However, research has shown that permeable pavements can become clogged over time and this reduces their infiltration capacity. In order to assess the infiltration of permeable pavements, a variety of infiltration test procedures have been utilised in the past. However, the results have generally been inconsistent, and have shown a large variation in the range of infiltration rates measured. This paper evaluates the performance of two new experimental test methods developed in the Netherlands to more accurately determine the surface infiltration rate of existing permeable pavement installations. The two methods were the falling head full-scale method and the constant head full-scale method. Both of the new methods involved inundating a large area of the pavement in order to determine the infiltration rate through the pavement surface. Double ring infiltrometer tests were also performed to enable a comparison of the results. The study found that the new falling head full-scale testing method produced the most accurate results.
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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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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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