Wolfgang Rauch
University of Innsbruck, Institute of Infrastructure, Faculty Member
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Urban water management is concerned with the supply of drinking water to households and industry and the discharge of stormwater and waste water from the urban environment. The system is highly dynamic and driven by meteorology, urban... more
Urban water management is concerned with the supply of drinking water to households and industry and the discharge of stormwater and waste water from the urban environment. The system is highly dynamic and driven by meteorology, urban development, change in land use and technological innovations. Key mechanisms in urban water systems are on the one hand the transport of water and substances in the environment and the pipe network and on the other hand the conversion of substances due to physical and biochemical processes. Urban water management thus requires computer simulations in time (ranging typically from hours to years) and space (one to three dimensions). With the models becoming more and more complex by simulation at detailed spatio-temporal scale and by simulating whole urban environments, the limits of traditional numerical methods have been reached. In this chapter three emerging topics in scientific computing in urban water management are discussed and the need for advanced software methods is exemplified.
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Smoothed Particle Hydrodynamics (SPH) is a numerical method to explore fluid flow phenomena based on the simulation of particle movement. As the motion of particles can be described accordingly to the physical behavior of fluids, the... more
Smoothed Particle Hydrodynamics (SPH) is a numerical method to explore fluid flow phenomena based on the simulation of particle movement. As the motion of particles can be described accordingly to the physical behavior of fluids, the overall picture resembles the true hydrodynamic phenomena. The method has been applied successfully in many fields, however no application is known for pipe flow hydrodynamics. Main reasons are the problems in implementing turbulence phenomena and the increased computational eort. In the paper we describe the fundamentals of SPH for use in pipe hydrodynamics, outline the present state of the implementation and indicate the way forward.
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For a sufficient calibration of an environmental model not only parameter sensitivity but also parameter identifiability is an important issue. In an identifiability analysis is it possible to analyze whether changes in one parameter can... more
For a sufficient calibration of an environmental model not only parameter sensitivity but also parameter identifiability is an important issue. In an identifiability analysis is it possible to analyze whether changes in one parameter can be compensated by appropriate changes of the other ones within a given uncertainty range. Such an analysis is conditional to a certain measurement layout, hence the influence of number and location of measurement sites can be investigated. In the present study identifiability analysis is applied to a conceptual model of a combined sewer system aiming to predict the combined sewer overflow emissions. Different measurement layouts are tested and it can be shown that only 13 of the most sensitive catchment areas (represented by the model parameter “effective impervious area”) can be identified when overflow measurements of the 20 highest overflows and the runoff to the waste water treatment plant is used for calibration. The main advantage of this method are very low computational costs as the number of required model runs equals the total number of model parameters. Hence, this method is a valuable tool when analyzing large models with a long runtime and many parameters.
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Sludge recirculation mixing in anaerobic digesters is essential for the stable operation of the digestion process. While often neglected, the configuration of the sludge inlet has a substantial influence on the efficiency of the mixing... more
Sludge recirculation mixing in anaerobic digesters is essential for the stable operation of the digestion process. While often neglected, the configuration of the sludge inlet has a substantial influence on the efficiency of the mixing process. The fluid is either injected directly into the enclosed fluid domain or splashes onto the free surface of the slurry flow. In this paper, the aim was to investigate the effect of the inlet configuration by means of computational fluid dynamics—using ANSYS Fluent. Single-phase and multi-phase models are applied for a submerged and splashing inlet, respectively. To reduce the high computational demand, we also develop surrogate single-phase models for the splashing inlet. The digester mixing is analyzed by comparing velocity contours, velocity profiles, mixing time and dead volume. The non-Newtonian characteristics of the sludge is considered, and a $$k-\varepsilon $$ k - ε model is employed for obtaining turbulence closure. Our method is valid...
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The city of Kiruna in Northern Sweden has become known for the need to relocate major parts of the city. Current and future mining activities in the world’s largest underground iron ore mine are the cause of land subsidence that requires... more
The city of Kiruna in Northern Sweden has become known for the need to relocate major parts of the city. Current and future mining activities in the world’s largest underground iron ore mine are the cause of land subsidence that requires relocation of substantial parts of the town including its water infrastructure. Figure 1 shows the area currently affected and projections thereof for the future. The process of relocating the city has started already and will continue for a few decades. It implies the construction of new urban areas and at the same time demolition in abandoned areas. With regard to the life span of water infrastructure, all actions taken now and in the near future will have an impact over five to ten decades. These circumstances place special demands on processes and technical solutions with regard to robustness, flexibility and mobility and require dealing with changes that cannot yet be foreseen.
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In dieser Arbeit wird ein moglicher Ubergang von grauer (traditioneller) zu grunerInfrastruktur anhand der Stadt Kiruna (Schweden) untersucht, in der in den nachsten Jahrzehnten einegrose Stadtumwa ...
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In this paper we describe the background, the concept and the current status of an international postgraduate course on the subject of integrated urban water systems. The course aims to overcome the typical fragmentation of the... more
In this paper we describe the background, the concept and the current status of an international postgraduate course on the subject of integrated urban water systems. The course aims to overcome the typical fragmentation of the engineering curricula in that field. Hence, the objective is to give a comprehensive overview on the total urban water and pollutant cycle, thus hoping to provide the students with a wider perspective on the problem. The course is structured into 22 modules that can also be taught in certain combinations. Emphasis is given to engineering problem solving and modeling.
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In the urban water cycle, there are different ways of handling stormwater runoff. Traditional systems mainly rely on underground piped, sometimes named 'gray' infrastructure. New and so-called 'green/blue' ambitions aim... more
In the urban water cycle, there are different ways of handling stormwater runoff. Traditional systems mainly rely on underground piped, sometimes named 'gray' infrastructure. New and so-called 'green/blue' ambitions aim for treating and conveying the runoff at the surface. Such concepts are mainly based on ground infiltration and temporal storage. In this work a methodology to create and compare different planning alternatives for stormwater handling on their pathways to a desired system state is presented. Investigations are made to assess the system performance and robustness when facing the deeply uncertain spatial and temporal developments in the future urban fabric, including impacts caused by climate change, urbanization and other disruptive events, like shifts in the network layout and interactions of 'gray' and 'green/blue' structures. With the Info-Gap robustness pathway method, three planning alternatives are evaluated to identify critical p...
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Successful river water quality modelling requires the specifi cation of an appropriate model structure and process formulation. Both must be related to the compartment stru cture of running water ecosystems including their lon- gitudinal,... more
Successful river water quality modelling requires the specifi cation of an appropriate model structure and process formulation. Both must be related to the compartment stru cture of running water ecosystems including their lon- gitudinal, vertical, and lateral zonation patterns. Furtherm ore, the temporal variability of abiotic boundary con- ditions may be important and must be incorporated by an appropria te
Research Interests: Environmental Science, Rivers, Eutrophication, Multidisciplinary, River water, and 11 moreAdvection, Steady state, Water Science and Technology, Constant Time Delay, Length scale, Dissolved Oxygen, River Water Quality, Water Quality Models, Boundary Condition, Temporal Variability, and Representation Politics
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Urban drainage systems are designed to capture the runoff for a certain return period of a design rainfall event. Typically, numerical models are used, which are calibrated by comparing model response and measured system performance. The... more
Urban drainage systems are designed to capture the runoff for a certain return period of a design rainfall event. Typically, numerical models are used, which are calibrated by comparing model response and measured system performance. The applicability of such models to predict the system behaviour under extreme events is unclear, as usually then no data are available. This paper describes the analysis of an extreme rainfall event in the year 2016. The event is characterized by a very short duration and very high rainfall intensities. The maximum-recorded rainfall peak was 47.1 mm rainfall within 10 min, which corresponds to a return period of 500 years. The event caused local flooding on streets, interruptions of traffic and damages in buildings. In order to improve the flood resilience of the city, the event was analysed with an existing 1D hydrodynamic model of the sewer system. Model results were compared to water level measurements in the drainage system and citizen observations...
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This paper investigates the minimization of the kernel and gradient errors introduced by refining particles. For the first time the computation of a minimizing function is depicted that can ease the choice of refinement parameters.... more
This paper investigates the minimization of the kernel and gradient errors introduced by refining particles. For the first time the computation of a minimizing function is depicted that can ease the choice of refinement parameters. Results for different refinement patterns are analyzed. Finally an application to a fully refined air bubble problem is considered, which leads to a description of the difficulties and implications when applying refinement to multiphase problems involving a high-density ratio of 1:1,000.
The lifespan of urban water networks (e.g. water supply and sewer) and other infrastructure systems (gas distribution, streets, etc.) is limited. While for networks in larger municipalities (>50,000 inhabitants) various rehabilitation... more
The lifespan of urban water networks (e.g. water supply and sewer) and other infrastructure systems (gas distribution, streets, etc.) is limited. While for networks in larger municipalities (>50,000 inhabitants) various rehabilitation models exist, rehabilitation management of networks in small municipalities (water supply, sewer, gas supply, etc.) usually depends mainly on expert knowledge and the experience of engineers, as models and reliable data for these networks are often missing. To analyze this problem, we investigated the integrated rehabilitation of infrastructure networks of a small municipality (13,100 inhabitants). Since, water supply, sewer and gas distribution network and condition/failure data were available, an integrated, multi-utility approach is enabled. For rehabilitation management a prioritization of street sections containing all available infrastructure was applied. Jointly with the priority of each network an overall priority of the areas is estimated for an integrated rehabilitation management.
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ABSTRACT In the past decades, the main focus of water supply management has moved from construction of new water supply networks to rehabilitation and adaptation of the existing infrastructure. The decision-making process for the... more
ABSTRACT In the past decades, the main focus of water supply management has moved from construction of new water supply networks to rehabilitation and adaptation of the existing infrastructure. The decision-making process for the rehabilitation management relies heavily on the quality of the applied deterioration model. A recurring problem in the application of such models relates to the quality and availability of network data. These data are often incomplete or unreliable because building measures and damages are only documented properly recently and the recovery of older data is difficult and expensive. A key point in rehabilitation planning is therefore data collection and data reconstruction. Consequently, the aim of this paper is to present a methodology for the enhancement of the available data of water supply networks and the prognosis of the necessary rehabilitation rates under limited data availability. Results indicate that the presented data reconstruction technique has advantages as compared to traditional data extrapolation. It also allows the reconstruction of fragmentary data about existing water supply and wastewater collection systems for the operating utilities. However, it cannot be used for reconstructing failure types as well as the whole information on pipes (e.g. more than two missing information).
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Successful river water quality modelling requires the specification of an appropriate model structure and process formulation. Both must be related to the compartment structure of running water ecosystems including their longitudinal,... more
Successful river water quality modelling requires the specification of an appropriate model structure and process formulation. Both must be related to the compartment structure of running water ecosystems including their longitudinal, vertical, and lateral zonation patterns. Furthermore, the temporal variability of abiotic boundary conditions may be important and must be incorporated by an appropriate choice of model parameters. A six-step decision procedure is proposed to achieve these objectives. The steps address the determination of the following model features: (1) temporal representation (dynamic or steady-state); (2) model dimensionality; (3) mixing; (4) advection; (5) reaction terms; and (6) boundary conditions. Numerical criteria based on process time constants and length scales provide a basis for these decisions.
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... Karsten Arnbjerg-Nielsen 1 Thorkild Hvitved-Jacobsen 2 Niels Bent Johansen 3 Peter SteenMikkelsen 4 Bjarne Kallesø Poulsen 1 Wolfgang Rauch 4 Flemming Schlütter 2 1 PH-Consult ApS 2 Aalborg Universitet. ... Mogens Kaasgaard,... more
... Karsten Arnbjerg-Nielsen 1 Thorkild Hvitved-Jacobsen 2 Niels Bent Johansen 3 Peter SteenMikkelsen 4 Bjarne Kallesø Poulsen 1 Wolfgang Rauch 4 Flemming Schlütter 2 1 PH-Consult ApS 2 Aalborg Universitet. ... Mogens Kaasgaard, Miljøstyrelsen Peter Steen Mikkelsen, IMT ...
There is a widespread need for a common terminology in modelling for water quality management. This paper points out sources of confusion in the communication between researchers due to misuse of existing terminology or use of unclear... more
There is a widespread need for a common terminology in modelling for water quality management. This paper points out sources of confusion in the communication between researchers due to misuse of existing terminology or use of unclear terminology. The paper attempts to clarify the context of the most widely used terms for characterising models and within the process of model building. It is essential to the ever growing society of researchers within water quality management, that communication is eased by establishing a common terminology. This should not be done by giving broader definitions of the terms, but by stressing the use of a stringent terminology. Therefore, the goal of the paper is to advocate the use of such a well defined and clear terminology.
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Research Interests: Environmental Science, Water, Urban Health, Medicine, Multidisciplinary, and 13 moreProbability, Stochastic processes, Heavy Metal, Polycyclic Aromatic Hydrocarbon, Rain, Sewage, Stochastic Model, Sewer System, Elsevier, Organic Compound, Urban Area, Environmental Problem, and total suspended solid (TSS)
... Villeurbanne cedex, France 6) Pennine Water Group, The University of Bradford, Richmond Road, Bradford, BD7 1DP * Corresponding author, e-mail: ana.deletic@eng.monash.edu Abstract The state of knowledge regarding uncertainties in... more
... Villeurbanne cedex, France 6) Pennine Water Group, The University of Bradford, Richmond Road, Bradford, BD7 1DP * Corresponding author, e-mail: ana.deletic@eng.monash.edu Abstract The state of knowledge regarding uncertainties in urban drainage models is poor, in ...
The use of urban drainage models requires careful calibration, where model parameters are selected in order to minimize the difference between measured and simulated results. It has been recognized that often more than one set of... more
The use of urban drainage models requires careful calibration, where model parameters are selected in order to minimize the difference between measured and simulated results. It has been recognized that often more than one set of calibration parameters can achieve similar model accuracy. A probability distribution of model parameters should therefore be constructed to examine the model's sensitivity to its parameters. With increasing complexity of models, it also becomes important to analyze the model parameter sensitivity while taking into account uncertainties in input and calibration data. In this study a Bayesian approach was used to develop a framework for quantification of impacts of uncertainties in the model inputs on the parameters of a simple integrated stormwater model for calculating runoff, total suspended solids and total nitrogen loads. The framework was applied to two catchments in Australia. It was found that only systematic rainfall errors have a significant im...
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This paper examines the performance of infiltration of wastewater into the groundwater due to leaks in sewer systems. Experiments were carried out under a variety of conditions using domestic sewage and uniform bedding material ranging in... more
This paper examines the performance of infiltration of wastewater into the groundwater due to leaks in sewer systems. Experiments were carried out under a variety of conditions using domestic sewage and uniform bedding material ranging in grain-size from 0 to 40 mm. The results indicate that the infiltration is determined solely by the physical process of the colmation of the bedding sand zone. Due to the accumulation of particles in the porous media the permeability of this zone and therefore the amount of infiltrated sewage is decreased rapidly with time. This effect is commonly known as colmation. A strong influence of both solids concentration of the sewage and grain-size of the bedding material can be seen on the temporal development of the colmation. Still a steady state flow was reached under all experimental conditions in less than an hour of infiltration. The characterisation of the colmated zone by the leakage factor presents the possibility to calculate the infiltrated se...
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ABSTRACT