Der Austausch zwischen Grundwasser und Kanalnetz kann in die Prozesse der Grundwasserinfiltration in Kanalnetze und der Abwasserexfiltration aus Kanalnetzen unterteilt werden. Generell entstehen durch die In- und Exfiltration (I/E) erhöhte Kosten der Abwasserentsorgung und eine Belastung für Boden, Grundwasser und Oberflächenwasser. Für Einschätzungen zur Dynamik und Quantität der In- und Exfiltration ist die Nutzung von Modellen sinnvoll, da zahlreiche Einflussfaktoren in die Betrachtungen einfließen können und dadurch eine komplexe Erfassung der Prozessmechanismen ermöglicht wird. Im Rahmen der vorliegenden Arbeit wurden physikalisch basierte Modelle zur Abbildung der In- und Exfiltrationsprozesse hinsichtlich erforderlicher Parameter und Randbedingungen analysiert und angewandt. Anhand detaillierter 3D-Modelle, kleintechnischer Versuche, Datenanalysen und statistischer Verfahren erfolgte die Modifizierung und Entwicklung von I/E-Modellen sowie die Parameteridentifikation zur Abbildung der In- und Exfiltration. Des Weiteren wurden die entwickelten Modellansätze mit einem hydrodynamischen Kanalnetzmodell verknüpft und großräumige Langzeitsimulationen durchgeführt. Die Untersuchungen zeigen bezüglich der Infiltration von Grundwasser in das Kanalnetz, dass eine physikalisch basierte Prozessmodellierung einer Abstraktion bedarf, um die 3-Dimensionalität des Prozesses in einem 1D-Modell wieder zu geben und dadurch die Anbindung an ein Kanalnetzmodell zu ermöglichen. Anhand von Simulationsrechnungen wurde festgestellt, dass die quantitative Betrachtung der Infiltration auf Einzugsgebietsebene keine hydrodynamische Modellierung erfordert. Signifikante quantitative Änderungen der Grundwasserinfiltration aufgrund der Wasserstandsschwankungen in den Kanälen sind nur lokal oder temporär von Bedeutung. Die Grundwasserinfiltration kann jedoch deutliche Auswirkungen auf die Ergebnisse der hydrodynamischen Simulation haben. Anhand von Datenanalysen im Einzugsgebiet Dresden konnte des Weiteren ein signifikanter Zusammenhang zwischen Infiltrationsparametern und Kanalzustand ermittelt werden. Der Exfiltrationsprozess kann durch ein 1D-Modell gut abgebildet werden, wobei der Prozess der Bodenkolmation anhand eines zeit- und potenzialabhängigen Modells implementiert werden kann. Ferner konnte durch die Verknüpfung mit Infiltrationsanalysen eine Ableitung der Schadensfläche erfolgen, die als Parameter in die Exfiltrationsmodellierung eingeht. Die hydrodynamischen Berechnungen zeigen, dass für die Exfiltrationsmodellierung eine möglichst exakte Berechnung der Wasserstände in Kanalnetzen essentiell ist. / The water exchange between groundwater and sewer system can be characterized by the processes of groundwater infiltration and sewerage exfiltration. Infiltration and exfiltration (I/E) cause an increase of the costs of sewerage management and a deterioration of soil, groundwater and the receiving surface water. In order to assess the dynamics and quantities of I/E, model applications can be used in order to include influencing factors and to afford a complex consideration of the process mechanisms. Within this work I/E-approaches were analyzed and modified in order to assess parameters and boundary conditions. The parameter identification and model development was realised according to the application of a detailed 3D-model, the realization of experiments, data analyses and the application of statistical methods. Furthermore the developed and modified approaches were coupled with a hydrodynamic sewer network model and long term simulations were performed. It was found that a physical based description of the infiltration process requires the implementation of the 3-dimensionality of the process. A hydrodynamic modelling of the sewer flow processes is not necessary to quantify infiltration rates on catchment scale, but the results of hydrodynamic modelling can be influenced significantly by groundwater infiltration. Furthermore data analyses of data of Dresden show a significant relationship between infiltration parameters and the condition class of the sewer pipes. The exfiltration process can be described by a 1D-model, whereat the processes of soil clogging are simulated by a time and potential based approach. Using the infiltration analyses it was possible to calculate the leak area, which is an important parameter of the exfiltration modelling. Hydrodynamic simulations show that the exfiltration modelling requires an accurate calculation of water levels in sewers.

Sewage exfiltration from a sanitary and combined sewer systems and its percolation into porous medium results in a clogged or colmation layer in the nearby soil. In order to develop a comprehensive understanding of raw sewage transport mechanisms in porous media, investigations were carried out on the micro-scale properties of the multiphase system. In our laboratory experiments, the role of surfactants as a major organic chemical compound in wastewater was evaluated by using a surfactant solution as an artificial wastewater percolating into a porous media, represented by using columns and Plexiglas model. We studied flows of water and surfactants solution in saturated porous medium to detect the dynamic effects by means of measuring pressure and permeability as well as by visualization of flow regions and consequence for porosity along interfaces between water and surfactants solution. The tests revealed that mechanisms at interfaces between fluids and solids as well as between water and surfactants solution (i.e. wastewater) are significantly influencing the flow behavior. At the interfaces surfactant molecules are adsorbed or accumulate, respectively, and subsequently inducing electrical charges to those layers, altering the properties of fluids and these interfaces. Depending on the conditions, channels might be narrowed and thus decreasing the flow rate with a later erosion and increase of flow rates, or the flow and thus the erosive capacity might become intensified along the interface between surfactants solution and neighbouring water. In conclusion, the results of tests proved the surfactants to be an important controlling factor in the hydraulic properties of wastewater percolating into soil.

Sewage exfiltration from a sanitary and combined sewer systems and its percolation into porous medium results in a clogged or colmation layer in the nearby soil. In order to develop a comprehensive understanding of raw sewage transport mechanisms in porous media, investigations were carried out on the micro-scale properties of the multiphase system. In our laboratory experiments, the role of surfactants as a major organic chemical compound in wastewater was evaluated by using a surfactant solution as an artificial wastewater percolating into a porous media, represented by using columns and Plexiglas model. We studied flows of water and surfactants solution in saturated porous medium to detect the dynamic effects by means of measuring pressure and permeability as well as by visualization of flow regions and consequence for porosity along interfaces between water and surfactants solution. The tests revealed that mechanisms at interfaces between fluids and solids as well as between water and surfactants solution (i.e. wastewater) are significantly influencing the flow behavior. At the interfaces surfactant molecules are adsorbed or accumulate, respectively, and subsequently inducing electrical charges to those layers, altering the properties of fluids and these interfaces. Depending on the conditions, channels might be narrowed and thus decreasing the flow rate with a later erosion and increase of flow rates, or the flow and thus the erosive capacity might become intensified along the interface between surfactants solution and neighbouring water. In conclusion, the results of tests proved the surfactants to be an important controlling factor in the hydraulic properties of wastewater percolating into soil.