Searched for: author%3A%22Clemens%2C+F.H.L.R.%22
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Rietveld, M.W.J. (author), Clemens, F.H.L.R. (author), Langeveld, J.G. (author)
Urban runoff remobilises solids and their associated pollutants from urban-built environments and transports them to drainage systems via gully pots. This study presents an extensive monitoring campaign on the solids loading to drainage systems, including 104 gully pots as sampling locations and lasting 2 years. The solids loading is modelled...
journal article 2022
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Clemens, F.H.L.R. (author), Lepot, M.J. (author), Blumensaat, Frank (author), Leutnant, Dominik (author), Gruber, Guenter (author)
Once data have been recorded, data validation procedures have to be conducted to assess the quality of the data, i.e. give a confidence grade. Furthermore, gaps may occur in time series and, depending on the purposes, these can be given values by application of e.g. interpolation. Since both aspects are strongly correlated, this chapter gives an...
book chapter 2021
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Larrarte, Frédérique (author), Lepot, M.J. (author), Clemens, F.H.L.R. (author), Bertrand-Krajewski, Jean-Luc (author), Ivetic, Damjan (author), Prodanovic, Dusan (author), Stegeman, B. (author)
The knowledge of water levels and discharges in urban drainage and stormwater management (UDSM) systems is of key importance to understand their functioning and processes, to evaluate their performance, and to provide data for modelling. In this chapter, devoted mainly to underground combined and separate sewer pipe systems, various methods and...
book chapter 2021
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Lepot, M.J. (author), Kapelan, Z. (author), Clemens, F.H.L.R. (author)
The knowledge of water levels and discharges in urban drainage and stormwater management (UDSM) systems is of key importance to understand their functioning and processes, to evaluate their performance, and to provide data for modelling. In this chapter, devoted mainly to underground combined and separate sewer pipe systems, various methods and...
book chapter 2021
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Bertrand-Krajewski, Jean-Luc (author), Clemens, F.H.L.R. (author), Lepot, M.J. (author)
This introductory chapter indicates why well-defined, high-standard, and reliable monitoring is a key aspect in the necessary evolution of urban drainage and stormwater management and why it should become routine practice. It provides a framework, guidelines, and recommendations to define monitoring objectives and means. It also presents the...
book chapter 2021
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Bertrand-Krajewski, Jean-Luc (author), Uhl, Mathias (author), Clemens, F.H.L.R. (author)
Assessing uncertainties in measurements must become a standard practice in the field of urban drainage andstormwater management. This chapter presents three standard methods to estimate uncertainties: the Type Amethod (repeated measurements), the Type B method (law of propagation of uncertainties) and the MCmethod (Monte Carlo method). Each...
book chapter 2021
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Duinmeijer, S.P.A. (author), Clemens, F.H.L.R. (author)
Experiments are conducted in a Ø600 mm tank to analyse the 3D motion of buoyant particles in the free-surface vortex flow. The experiments revealed two stages in the particle motion: stage 1 is the helical motion along the vortex air core and stage 2 is the axial motion inside the vortex core. The stage 1 motion is sensitive to the particle’s...
journal article 2021
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Schellart, Alma N.A. (author), Blumensaat, Frank (author), Clemens, F.H.L.R. (author), van der Werf, J.A. (author), Mohtar, Wan Hanna Melina Wan (author), Ramly, Salwa (author), Muhammad, Nur (author), Bonneau, Jérémie (author), Fletcher, Tim D. (author)
Data collection in urban drainage systems comes with many challenges. However, many examples already exist, containing numerous useful lessons learned. This chapter therefore contains several urban drainage and stormwater management metrology case studies, selected to cover a wide range of scopes, scales, objectives, climates, data validation...
book chapter 2021
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Makris, K. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Polyvinyl chloride (PVC) sewer pipes have operated for decades in a hostile environment, raising concern among sewer managers over the longevity of their drainage systems. Inspection data (CCTV and Panoramo®) reveals that severe defects have already surfaced, yet it is unknown if the material properties of PVC sewers have been affected. In...
journal article 2021
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Rietveld, M.W.J. (author), Clemens, F.H.L.R. (author), Langeveld, J.G. (author)
Runoff (re)mobilises solids and their associated pollutants from streets and transports them via gully pots to the drainage system. As the solids negatively impact the performance of the drainage systems, knowledge on the solids loading in terms of mass and composition is essential. However, monitoring data on the solids loading, in...
journal article 2021
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Meijer, D.H. (author), Post, Johan (author), van der Hoek, J.P. (author), Korving, Hans (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Drinking water distribution networks (WDNs) are a crucial infrastructure for life in cities. Deterioration of this ageing, and partly hidden from view, infrastructure can result in losses due to leakage and an increased contamination risk. To counteract this, maintenance strategies are required to maintain the service level. Information on...
journal article 2021
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Rietveld, M.W.J. (author), de Rijke, D. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)
Urban runoff (re)mobilises solids present on the street surface and transport them to urban drainage systems. The solids reduce the hydraulic capacity of the drainage system due to sedimentation and on the quality of receiving water bodies due to discharges via outfalls and combined sewer overflows (CSOs) of solids and associated pollutants....
journal article 2020
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Duinmeijer, S.P.A. (author), Oldenziel, G. (author), Clemens, F.H.L.R. (author)
In order to analyse the flow characteristics of free-surface vortexes and to validate the Burgers vortex model by using stereo particle image velocimetry, experiments are conducted in a 600 mm diameter vortex tank. Measured axial velocities indicate that 10–25% of the flow is transported through the vortex core. The velocity profiles show that...
journal article 2020
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Thota Radhakrishnan, A.K. (author), Poelma, C. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
Transition from laminar to turbulent flow of non-Newtonian fluids is investigated using velocimetry data. These data are obtained by applying particle image velocimetry to images obtained through ultrasound imaging (echography). This yielded the observation of intermittent structures (puffs and slugs) that are formed during transition. Post...
journal article 2020
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Rietveld, M.W.J. (author), Clemens, F.H.L.R. (author), Langeveld, J.G. (author)
Gully pots are utilized for conveying runoff to drainage systems, as well as for reducing the system’s solids loading by retaining suspended solids. However, the accumulation of solids in gully pots reduces their removal efficiency, leading to an increase in solids transport towards the drainage system. This article aims to identify the main...
journal article 2020
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Mehta, D. (author), Thota Radhakrishnan, A.K. (author), van Lier, J.B. (author), Clemens, F.H.L.R. (author)
This article concerns the turbulent flow of Herschel–Bulkley slurries through circular horizontal pipes; in particular, that of concentrated domestic slurry obtained upon separation of domestic waste water and reduction in the use of water for domestic purposes. Experiments with a rheologically equivalent clay (kaolin) slurry indicated a non...
journal article 2020
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Rietveld, M.W.J. (author), Clemens, F.H.L.R. (author), Langeveld, J.G. (author)
Runoff entering urban drainage systems contains suspended solids, which carry pollutants and may cause blockages in downstream parts of the system (for example infiltration facilities). Suspended solids inflow should, therefore, preferably be controlled by solids removal at gully pots. This paper presents the results of lab experiments on the...
journal article 2020
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Tscheikner-Gratl, F. (author), Bellos, Vasilis (author), Schellart, Alma (author), Moreno Rodenas, A. (author), Muthusamy, Manoranjan (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author), Shucksmith, James (author), Heuvelink, Gerard B.M. (author)
This paper aims to stimulate discussion based on the experiences derived from the QUICS project (Quantifying Uncertainty in Integrated Catchment Studies). First it briefly discusses the current state of knowledge on uncertainties in sub-models of integrated catchment models and the existing frameworks for analysing uncertainty. Furthermore, it...
review 2019
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Stegeman, B. (author), Langeveld, J.G. (author), Bogaard, T.A. (author), Clemens, F.H.L.R. (author)
Due to the ageing of our underground wastewater infrastructure, leakage of sewers and pressure mains and subsequent infiltration or exfiltration are becoming an increasingly important issue. Herein, we present a novel method to detect and potentially quantify exfiltration from sewer systems under variable flow conditions; the DEST method. The...
conference paper 2019
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Tscheikner-Gratl, Franz (author), Caradot, Nicolas (author), Cherqui, Frederic (author), Leitão, Joao P. (author), Langeveld, J.G. (author), Scholten, L. (author), Lepot, M.J. (author), Stegeman, B. (author), Clemens, F.H.L.R. (author)
Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced...
review 2019
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