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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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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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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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Moreno Rodenas, A. (author), Tscheikner-Gratl, F. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)Receiving water quality simulation in highly urbanised areas requires the integration of several processes occurring at different space-time scales. These integrated catchment models deliver results with a significant uncertainty level associated. Still, uncertainty analysis is seldom applied in practice and the relative contribution of the...journal article 2019
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Moreno Rodenas, A. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)Water quality environmental assessment often requires the joint simulation of several subsystems (e.g. wastewater treatment processes, urban drainage and receiving water bodies). The complexity of these integrated catchment models grows fast, leading to potentially over-parameterised and computationally expensive models. The receiving water body...journal article 2019
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Moreno Rodenas, A. (author), Bellos, V. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)This work presents a method to emulate the flow dynamics of physically based hydrodynamic simulators under variations of time-dependent rainfall and parametric scenarios. Although surrogate modelling is often employed to deal with the computational burden of this type of simulators, common techniques used for model emulation as polynomial...journal article 2018
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Nieuwenhuis, E.M. (author), Post, J.A.B. (author), Duinmeijer, S.P.A. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)The accumulation of FOG (Fat, Oil and Grease) deposits in sewer pumping stations results in an increase in maintenance costs, malfunctioning of pumps and, a potential increase of wastewater spills in receiving open water bodies. It is thought that a variety of parameters (e.g. geometry of the pump sump, pump operation, socioeconomic...journal article 2018
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van Bijnen, J.A.C. (author), Korving, J.L. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)Due to a variety of contaminants in floodwater, exposure to urban pluvial flooding may pose a health risk to humans. In-sewer defects may cause increased pluvial flooding, possibly increasing health risks. This paper addresses the impact of in-sewer defects on urban pluvial flooding and, subsequently, on infection probabilities for humans. As...journal article 2018
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Mahmoodian, M. (author), Torres-Matallana, Jairo Arturo (author), Leopold, Ulrich (author), Schutz, Georges (author), Clemens, F.H.L.R. (author)In this study, applicability of a data-driven Gaussian Process Emulator (GPE) technique to develop a dynamic surrogate model for a computationally expensive urban drainage simulator is investigated. Considering rainfall time series as the main driving force is a challenge in this regard due to the high dimensionality problem. However, this...journal article 2018
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Mahmoodian, M. (author), Carbajal, Juan Pablo (author), Bellos, Vasilis (author), Leopold, Ulrich (author), Schutz, Georges (author), Clemens, F.H.L.R. (author)Urban drainage modelling typically requires development of highly detailed simulators due to the nature of various underlying surface and drainage processes, which makes them computationally too expensive. Application of such simulators is still challenging in activities such as real-time control (RTC), uncertainty quantification analysis or...journal article 2018
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Moreno Rodenas, A. (author), Cecinati, Francesca (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)Integrated Catchment Modelling aims to simulate jointly urban drainage systems, wastewater treatment plant and rivers. The effect of rainfall input uncertainties in the modelling of individual urban drainage systems has been discussed in several studies already. However, this influence changes when simultaneously simulating several urban...journal article 2017
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Elias Maxil, J.A. (author), Hofman, J.A.M.H. (author), Wols, B.A. (author), Clemens, F.H.L.R. (author), van der Hoek, J.P. (author), Rietveld, L.C. (author)This paper presents a model (inspired by another model) to calculate water temperature in free-surface flow with two main innovations: the convective heat transfer occurs only at the wetted perimeter of pipes, and the model was integrated to commercial software used for hydraulic calculations in drainage systems. Given these innovations, we...journal article 2017
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van Daal-Rombouts, P.M.M. (author), Gruber, Günter (author), Langeveld, J.G. (author), Muschalla, Dirk (author), Clemens, F.H.L.R. (author)Real time control (RTC) is generally viewed as a viable method for optimising the performance of urban wastewater systems. A literature review on the performance evaluation of RTC demonstrated a lack of consensus on how to do this. Two main deficiencies were identified: omitting uncertainty analysis and applying limited evaluation periods. A...journal article 2017
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Post, J.A.B. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)The performance of lateral house connections has a direct impact on sewer serviceability. Despite the potential consequences of a blockage, these components are generally maintained with a reactive approach. As inspection data on the condition of lateral house connections are scarce, this study adopts a statistical procedure to support...journal article 2016
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van Daal-Rombouts, P.M.M. (author), Sun, Siao (author), Langeveld, J.G. (author), Bertrand-Krajewski, J.-L. (author), Clemens, F.H.L.R. (author)Optimisation or real time control (RTC) studies in wastewater systems increasingly require rapid simulations of sewer systems in extensive catchments. To reduce the simulation time calibrated simplified models are applied, with the performance generally based on the goodness of fit of the calibration. In this research the performance of three...journal article 2016
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Moreno Rodenas, A. (author), Cecinati, F. (author), ten Veldhuis, Marie-claire (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)This study addresses the effect of spatial and temporal resolution of rainfall fields on the performance of a simplified integrated catchment model for predicting dissolved oxygen concentrations in a river. For that purpose we propose a procedure to generate rainfall products with increasing spatial information at different time step...conference paper 2016
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van Riel, W. (author), Post, J.A.B. (author), Langeveld, J.G. (author), Herder, P.M. (author), Clemens, F.H.L.R. (author)Operational decision-making processes for networked infrastructure management often occur as a multi-actor planning problem, implying these are based on negotiations between different stakeholders in addition to available system quality information. As such, does more accurate data about actual structural condition lead to other or better...journal article 2016
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Post, J.A.B. (author), Pothof, I.W.M. (author), Dirksen, J. (author), Baars, E. J. (author), Langeveld, J.G. (author), Clemens, F.H.L.R. (author)Gully pots are essential assets designed to relief the downstream system by trapping solids and attached pollutants suspended in runoff. This study applied a methodology to develop a quantitative gully pot sedimentation and blockage model. To this end, sediment bed level time series from 300 gully pots, spanning 15 months, were collected. A...journal article 2016
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Rombouts, P.M.M. (author), Tralli, A. (author), Langeveld, J.G. (author), Verhaart, F. (author), Clemens, F.H.L.R. (author)Being able to accurately determine weir discharges is of key importance in urban water management. The most common method is performing a level measurement and calculating the discharge using the standard weir equation. Since this equation is only valid in certain conditions, this can lead to large deviations from the actual discharge. In this...conference paper 2014
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- Clemens, F.H.L.R. (author) doctoral thesis 2001