Showing papers by "Francois Clemens published in 2012"
TL;DR: Using data from the Eindhoven wastewater system in The Netherlands both dry weather flow and wet weather flow situations have been studied, finding the smallest catchment area consistently shows the largest mean peak factors and vice versa.
24 citations
04 Sep 2012
TL;DR: The results of full-scale experiments aiming to quantify the detection limits for illicit connections under various sewer conditions are described and a new monitoring set-up for (partially) filled sewer conduits has been proposed.
Abstract: Distributed Temperature Sensing (DTS) with fiber-optic cables is a powerful tool to detect illicit connections in storm sewer systems. High frequency temperature measurements along the in-sewer cable create a detailed representation of temperature anomalies due to illicit discharges. The detection limits of the monitoring equipment itself are well-known, but there is little information available on detection limits for the discovery of illicit connections, as in sewers mixing and attenuation also plays an important role. This paper describes the results of full-scale experiments aiming to quantify the detection limits for illicit connections under various sewer conditions. Based on the results, a new monitoring setup for (partially) filled sewer conduits has been proposed.
16 citations
TL;DR: It is shown that settlement significantly influences sewer system functioning within the lifetime of a sewer (system).
13 citations
TL;DR: This paper presents the results of a study in two research catchments on the impact of in-sewer defects on urban pluvial flooding at network level using Monte Carlo simulations with a full hydrodynamic model of the sewer system.
12 citations
31 Dec 2012
TL;DR: In this article, the authors focus on determining the information required to be able to detect and identify sewer failure mechanisms using a HAZOP approach, and identify the main processes and defects responsible for the structural/operational failures of sewer elements, as well as possibility of obtaining the information about them.
Abstract: Asset management is a prerequisite for maintaining the required level of serviceability of urban drainage systems. The required asset management effort to achieve a certain level of service is unclear due to sewer systems process and structure complexity. One of the main questions of asset management is what kind of information is needed, and how this information can be obtained. Sewer failure mechanisms explain the structural/operational failures of sewer elements. This study focuses on determining the information required to be able to detect and identify sewer failure mechanisms. In order to be able to identify the failure mechanisms involved, a HAZOP approach was applied. The main processes and defects responsible for the structural/operational failures of sewer elements were identified, as well as possibility of obtaining the information about them. This information will help in estimating the probability of failure occurrence and generally it will help defining the information needed for proper serviceability.
5 citations
14 Jul 2012
TL;DR: In this paper, the authors established relationships between rainfall extremes and damage data from Dutch insurance industry and showed that there is a weak relationship between property damage and rainfall intensities, and that rainfall-related damage mainly occurs during summer seasons.
Abstract: The objective of this paper is to establish relationships between rainfall extremes and damage data from Dutch insurance industry. Rainfall data are based on a network of 33 automatic rain gauges held by the Royal Netherlands Meteorological Institute. Rainfall characteristics, such as peak rainfall intensity and rainfall volume, are correlated with damage statistics of claims in the vicinity of the rain gauges. The results show that rainfallrelated damage mainly occurs during summer seasons. There is a weak relationship between property damage and rainfall intensities and between property damage and rainfall volumes for summer events. More data is needed to confirm these relationships. In a subsequent study this will be investigated by using weather radar data to obtain a higher spatial rainfall resolution and thus be able to include more insurance data.
3 citations
31 Dec 2012
TL;DR: In this article, the authors presented new experimental data on the breakdown and removal of large air pockets in water pipelines and hydropower tunnels, and compared the experimental results with the numerical model.
Abstract: Air-water flow is an undesired condition in water pipelines and hydropower tunnels. Water pipelines and wastewater pressure mains in particular are subject to air pocket accumulation in downward sloping reaches, such as inverted siphons or terrain slopes. Air pockets cause energy losses and an associated capacity reduction. Despite its practical relevance, many phenomena associated with airwater flow in downward sloping pipe reaches are still poorly understood. Deltares and Delft University of Technology have investigated the co-current flow of air and water in twelve different large-scale facilities. Pothof and Clemens have recently developed a numerical model for the total air discharge by flowing water in downward sloping pipes. The model has been validated against the experimental data on co-current air-water flow and available literature. This paper presents new experimental data on the breakdown and removal of large air pockets. The experimental results are compared with the numerical model. The observed disagreement is analysed and discussed. The main conclusion is that the numerical model predicts the air pocket breakdown rate with reasonable accuracy.
3 citations
31 Dec 2012
TL;DR: In this paper, the authors compare visual inspection and drill core analysis in order to enhance further understanding of the limitations and potentials of both methods and show that both methods are associated with large uncertainties.
Abstract: Sewer systems are costly to construct and even more costly to replace, requiring proper asset management Sewer asset management relies to a large extent on available information. In sewer systems where pipe corrosion is the dominant failure mechanism, visual inspection (CCTV) and core sampling are amongst the methods applied mostly to assess sewer pipe condition. This paper compares visual inspection and drill core analysis in order to enhance further understanding of the limitations and potentials of both methods. Both methods have been applied on a selected sewer reach in the city of the Hague, which was reportedly subject to pipe corrosion. Results show that both methods, visual inspection and core sampling, are associated with large uncertainties and that there is no obvious correlation between results of visual inspection and results of drill core analysis.
3 citations
31 Dec 2012
TL;DR: In this paper, Rioleringsbeheer is eerste vereiste om het gewenste niveau van functioneren van de riolering te behouden.
Abstract: Rioleringsbeheer is een eerste vereiste om het gewenste niveau van functioneren van de riolering te behouden Welke inspanning op het gebied van rioleringsbeheer nodig is om een bepaald niveau van functioneren te bereiken is onduidelijk, omdat zowel de processen in als de structuur van de rioolstelsels complex zijn Een belangrijke vraag hierbij is welke informatie er nodig is en hoe deze informatie verkregen moet worden Faaimechanismen van het rioolsysteem verklaren het structurele en operationele falen van onderdelen van het rioolsysteem Deze studie richt zich op het vaststellen welke informatie er nodig is om faalmechanismen in de riolering op te sporen en te identificeren Om het identificeren van de faalmechanismen mogelijk te maken, is gebruik gemaakt van de zogenaamde HAZOP (Hazard+OPerability) benadering De belangrijkste processen en tekortkomingen verantwoordelijk voor het structurele en/of operationele falen van rioleringsonderdelen zijn geidentificeerd, evenab de mogelijkheden om de ervoor benodigde informatie te verkrijgen Deze informatie is nodig om de kans op een faalgebeurtenis te kunnen schatten en is uiteindelijk ook nodig om vast te stellen welke informatie nodig is voor goed functioneren van het systeem
1 citations
04 Sep 2012
TL;DR: Kallisto as discussed by the authors is a large scale research project at water board De Dommel in The Netherlands, in cooperation with several partners, which consists of quantitative and qualitative continuous on line measurements and extended modelling of the WWTP (Waste Water Treatment Plant) Eindhoven, the contributing sewer systems and the river Dommel.
Abstract: Kallisto is a large scale research project at water board De Dommel in The Netherlands, in cooperation with several partners (Weijers et al, 2011). It consists of quantitative and qualitative continuous on line measurements and extended modelling of the WWTP (Waste Water Treatment Plant) Eindhoven, the contributing sewer systems and the river Dommel. The overall goal of the project is to optimise the performance of the total wastewater system by using impact based Real Time Control (RTC) in order to comply with the WFD (water framework directive).
01 Jan 2012
TL;DR: Kallisto as mentioned in this paper is a large scale research project at water board De Dommel in The Netherlands, in cooperation with several partners, which consists of quantitative and qualitative continuous on line measurements and extended modelling of the WWTP (Waste Water Treatment Plant) Eindhoven, the contributing sewer systems and the river Dommel.
Abstract: Kallisto is a large scale research project at water board De Dommel in The Netherlands, in cooperation with several partners (Weijers et al, 2011). It consists of quantitative and qualitative continuous on line measurements and extended modelling of the WWTP (Waste Water Treatment Plant) Eindhoven, the contributing sewer systems and the river Dommel. The overall goal of the project is to optimise the performance of the total wastewater system by using impact based Real Time Control (RTC) in order to comply with the WFD (water framework directive).