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Many pressurized sewer systems do not reach their design capacity discharge due to enlarged resistance in the pipe system. An extensive investigation has brought to light that air pockets in pipe systems are an important cause of high resistance in sewer system pipe lines. Air intake by pumps in sumps is one of the main reasons of air pocket formation in sewer systems. But there is still little known about air entrainment due to plunging jets from circular open channels, and air intake by submersible pumps near plunging jets, especially at the scale of real sewer sumps. The research objective is to achieve knowledge and insight into air entrainment from free overfall water jets from horizontal open channels and air bubble intake with submersible sewer pumps. The main questions are: - How does the air entrain into the reservoir? - Where and how many air bubbles can be expected in a certain configuration without any specific measures? - What is the sphere of influence of the submersible sewer pump? - What is a robust measure to prevent air coming into the sewer pump?

Introduction Flooding is a natural phenomenon, but human activity has significantly altered the natural drainage processes thereby occasionally causing greater flood risk. Urban flooding has become more frequent due to a number of factors including climate change, urban growth and an increase in paved surfaces. Pluvial flooding results from heavy rainfall when water that does not infiltrate into the ground ponds in hollows or flows over the ground. In flood damage estimation, the concept of damage curves or damage functions is applied. Such functions give the building damage due to inundation. Most damage assessment models have in common that the direct monetary damage is obtained from the type of the element at risk and the inundation depth. Problem definition Flood damage assessment models do not focus solely on pluvial flood damage estimation. In addition, the existing flood damage models and developed depth-damage curves have not been tested for application of pluvial flood events. Research This study is carried out with the main objective to test the flood damage assessment model HOWAD-PREVENT in a case study in Rotterdam and to evaluate the uncertainty and sensitivity of this model. The model applicability and sensitivity was tested by running the model with two building type files together with three water level files.

Nieuwe KNMI-klimaatscenario’s: grotere rioleringen? Veel artikelen wijzen, na de openbaarmaking van de nieuwste inzichten van het KNMI over de ontwikkeling van het klimaat in Nederland, in die richting. Maar is dat niet te kort door de bocht?

Insurance databases form a promising data source that can be used to improve pluvial flood damage estimations. This paper describes the key characteristics of an insurance database on water related damages to private buildings and content in the Netherlands that has been made available for research. The paper presents preliminary results of a case study where insurance data are explored to find relationships between rainfall characteristics and pluvial flood damage. The results show that variations in damage are partly related to rainfall characteristics. More research on rainfall characteristics and other explanatory variables of flood damage is needed to capture the processes causing damage.

Urban pluvial flood management requires detailed spatial and temporal information on flood characteristics and damaging consequences. There is lack of quantitative field data on pluvial flooding resulting in large uncertainties in urban flood model calculations and ensuing decisions for investments in flood protection. In this paper four different data sources are discussed, based on literature and expert consultation, that are believed to be of value for the acquisition of quantitative data on pluvial flooding. Data assembled by insurance agencies on flood damage, call databases held by water authorities and emergency services and remote sensing images cover years of observational data that can be mined to obtain data on flood characteristics and occurrence. Flood monitoring using sensor technology can be effective to collect additional pluvial flood data, that is not captured by existing data sources.

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.

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.

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).

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.

Van 3 tot en met 7 september 2012 is de negende Urban Drainage Modelling conferentie gehouden in Belgrado, de hoofdstad van Seme. Hieronder volgt een verslag van de indrukken die zijn opgedaan in Servië en de belangrijkste, wetenschappelijke ontwikkelingen die aan de orde zijn gekomen. Het congres had een vol wetenschappelijk programma, mede doordat de organisatie ook graag de stad en het land wilde promoten.