This thesis presents a novel analytical solution strategy for the zero-inertia (ZI) equations of free surface flow. These equations are utilized herein for routing flood flow in open channels and for simulating excess rainfall runoff on overland planes. The novel solution approach is shown to be both accurate and robust, especially under the complicated and intricate conditions of infiltrating flow on initially dry river beds or soils, e.g., as present in arid and semiarid areas. This is underlain by comparing modeling results of the novel analytical procedure with those of validated numerical solutions. Furthermore, it is shown that the analytical ZI model can deliver a process-oriented portrayal of runoff concentration in the flood-generating parts of the catchment. Subsequently, the novel analytical ZI model is applied for a real-world water management problem in the Sultanate of Oman, Arabian Peninsula. Within an integrated flash flood routing model—which is also presented in this thesis—the novel analytical routing approach helps in accurately matching the dynamics of advancing and infiltrating ephemeral river flow, established as a consequence of release from a groundwater recharge dam. The integrated modeling system houses the aforementioned analytical downstream model and tailor-made, state-of-the-art modeling components to portray the upstream flow processes, dam operation (including evaporation), and spillway release flow. The proposed modeling system can aid in rendering a realistic image of transient transmission losses and dependent flow dynamics. This is of extremely high importance for water resources assessment, as well as for optimizing recharge dam operation strategies in order to maximize downstream transmission losses and, thus, groundwater recharge. / Diese Dissertation präsentiert einen neuartigen analytischen Lösungsansatz für das beschleunigungsfreie Wellenmodell (bzw. „Zero-Inertia-Modell“, „ZI-Modell“, oder „diffusives Wellenmodell“). Im Rahmen der Arbeit wird das hergeleitete hydrodynamische Modell sowohl zur Simulation von Freispiegelabflüssen in nichtprismatischen und durchlässigen Gerinnen, als auch für die Beschreibung von auf der Landoberfläche abfließendem Infiltrationsüberschuss eingesetzt. Es wird gezeigt, dass der neuartige analytische Ansatz — im Hinblick auf Massenerhaltung und die exakte Abbildung der Abflussdynamik — akkurate Ergebnisse liefert und gleichzeitig unter komplexen und verwickelten Prozessbedingungen anwendbar ist. So belegt eine vergleichende Analyse mit validierten numerischen Lösungsansätzen die Robustheit des analytischen ZI-Modells. Insbesondere die im Sinne der numerischen Mathematik stabile und genaue Modellierung der gekoppelten Abfluss- und Infiltrationsvorgänge in anfänglich trockenen Gerinnen ist dabei ein Novum. Weiterhin wird die Eignung und Anwendbarkeit des neuartigen Modellansatzes zur Beschreibung der Abflusskonzentrationsprozesse gezeigt. Der neuartige Lösungsansatz wird im Folgenden für ein reales Wassermanagementproblem im Sultanat Oman, Arabische Halbinsel eingesetzt. Als Bestandteil eines integrierten Modellsystems, welches ebenfalls im Rahmen der Dissertation vorgestellt wird, dient das analytische ZI-Modell zur Simulation von infiltrierendem Wadiabfluss, welcher unterstrom von Grundwasseranreicherungsdämmen starke Verluste von Masse und Impuls erfährt. Zusammen mit maßgeschneiderten und dem Stand der Technik entsprechenden Komponenten für die Betriebssimulation des Anreicherungsdammes (inklusive Verdunstung von der freien Seefläche) sowie für die Abbildung der oberstromigen hydrodynamischen Prozesse (ebenfalls inklusive Infiltration) wird der neuartige analytische Ansatz in einem Modellsystem zusammengefasst. Das Modellsystem ist in der Lage ein realistisches Bild der raumzeitlichen Dynamik des Abflusses sowie der Grundwasserneubildung aus infiltrierendem Wadiabfluss zu liefern. Damit stellt das Modellsystem ein wertvolles Werkzeug sowohl zur Wasserdargebotsermittlung, als auch für die Optimierung des Betriebes von Grundwasseranreicherungsdämmen dar.

This thesis explores the losses occurring in a specific region located in the southern part of Eskilstuna, where ESEM serves as the network owner. The study places particular emphasis on power factor and load factor as key factors. Its objective is to analyze and comprehend the extent of losses in the network and their implications. The results demonstrate that losses in the chosen area of the Eskilstuna network align with prior research and theoretical expectations. Based on calculations, the losses in this network segment amount to approximately 483 MWh per year, corresponding to a cost of approximately 272,000 Swedish Kronor for ESEM in 2022. The method of studies is based on calculations, analyzer, and literature studies to achieve a reliable result. The results show that losses within the selected area of the Eskilstuna network are consistent with previous research and theoretical expectations. Of the total loss, there are some customers who show larger losses compared to the average case. These customers were identified, and a summary analysis was made of their power factor and load factor standard deviation. These losses depend on various factors, such as the existence of reactive power, technical and non-technical losses. Measures to deal with these problems are suggested based on previous research and literature studies. Optimization of transformers, phase compensation and monitoring are some of these measures. This study provides significant insights into power grid losses and proposes potential strategies to mitigate these losses in the examined region. By minimizing such losses, ESEM has the potential to enhance the efficiency of the electrical grid, lower carbon dioxide emissions, and enhance economic outcomes for energy producers, the electricity grid operator, and consumers. For continued progress in the field, further research, and implementation of the proposed measures to streamline the power grid and reduce losses in the future is recommended. / Elnätförluster har konsekvenser för miljön, energisystemet och slutanvändarna. När energi går förlorad i elnätet minskar den totala effektiviteten i systemet och ökar belastningen på kraftgenereringen. Detta kan leda till ökade kostnader för energiproducenter och potentiellt högre priser för konsumenterna. Dessutom kan ökade elnätförluster bidra till en ökning av koldioxidutsläppen från kraftverken och därmed ha en negativ miljöpåverkan. Syftet med studien är att undersöka det befintliga elnätet i det utvalda området genom analys av data från mät-elnätavdelningen i ESEM. Metoden för studien är baserad på beräkningar, analyser och litteraturstudier för att uppnå ett pålitligt resultat. Resultaten visar att förluster inom det valda området av Eskilstunanätverket överensstämmer med tidigare forskning och teoretiska förväntningar. Baserat på beräkningar uppgår förlusterna i detta nätsegment till cirka 483 MWh, vilket motsvarar en kostnad på cirka 272 000 svenska kronor för ESEM 2022. Av den totala förlusten finns det vissa kunder som uppvisar större förluster jämfört med genomsnittsfallet. Dessa kunder identifierades, och en översiktsanalys gjordes av deras effektfaktor och standardavvikelse för belastningsfaktorn. Dessa förluster beror på olika faktorer, såsom existensen av reaktiv effekt, tekniska och icke-tekniska förluster. Åtgärder för att hantera dessa problem föreslås baserat på tidigare forskning och litteraturstudier. Optimering av transformatorer, faskompensering och övervakning är några av dessa åtgärder. Denna studie bidrar med viktig kunskap om elnätförluster och identifierar potentiella åtgärder för att minska förlusterna i det studerade området. Genom att minska förlusterna kan man öka elnätets effektivitet, minska koldioxidutsläppen och förbättra ekonomiska aspekter för energiproducenter, elnätägaren och konsumenter. För fortsatta framsteg inom området rekommenderas ytterligare forskning och implementering av de föreslagna åtgärderna för att effektivisera elnätet och minska förlusterna i framtiden.

This thesis presents a novel analytical solution strategy for the zero-inertia (ZI) equations of free surface flow. These equations are utilized herein for routing flood flow in open channels and for simulating excess rainfall runoff on overland planes. The novel solution approach is shown to be both accurate and robust, especially under the complicated and intricate conditions of infiltrating flow on initially dry river beds or soils, e.g., as present in arid and semiarid areas. This is underlain by comparing modeling results of the novel analytical procedure with those of validated numerical solutions. Furthermore, it is shown that the analytical ZI model can deliver a process-oriented portrayal of runoff concentration in the flood-generating parts of the catchment. Subsequently, the novel analytical ZI model is applied for a real-world water management problem in the Sultanate of Oman, Arabian Peninsula. Within an integrated flash flood routing model—which is also presented in this thesis—the novel analytical routing approach helps in accurately matching the dynamics of advancing and infiltrating ephemeral river flow, established as a consequence of release from a groundwater recharge dam. The integrated modeling system houses the aforementioned analytical downstream model and tailor-made, state-of-the-art modeling components to portray the upstream flow processes, dam operation (including evaporation), and spillway release flow. The proposed modeling system can aid in rendering a realistic image of transient transmission losses and dependent flow dynamics. This is of extremely high importance for water resources assessment, as well as for optimizing recharge dam operation strategies in order to maximize downstream transmission losses and, thus, groundwater recharge.:List of Figures List of Tables List of Algorithms List of Symbols and Acronyms 1 Introduction 1.1 The Role of Ephemeral River Flow for Groundwater Recharge 1.2 Methods for Estimating Groundwater Recharge 1.3 Groundwater Augmentation Techniques and the Involved Processes 1.4 The Role of Overland Flow for Flash Flood Formation 1.5 Objectives of the Thesis 1.6 Structure of the Work 2 Literature Review 2.1 Surface-Water Based Studies on the Estimation of Indirect Recharge 2.2 Review of Literature on Process-Oriented Overland Flow Modeling 2.3 Summary 3 Principles of Physically-Based Modeling of Infiltrating Free Surface Flows 3.1 Hydraulic Phases of an Infiltrating Flow Event 3.2 Hydrodynamic Models 3.2.1 The Saint-Venant Equations 3.2.2 Zero-Inertia Approximation 3.2.3 Kinematic Wave Approximation 3.2.4 Other Simplifications of the Full Hydrodynamic Model 3.3 Initial and Boundary Conditions 3.4 Relating Friction and Flow Properties 3.5 Accounting for Losses or Gains 3.6 Including Arbitrary Cross-Sectional Geometries 3.7 Discussion of the Reviewed Flow Models 3.7.1 Discussion of Modeling Approaches for Ephemeral River Routing 3.7.2 A Suitable Hydrodynamic Model for Overland Flow 3.7.3 On the Portrayal of Shocks with the Kinematic Wave Model 3.8 Summary 4 Solution Procedures for the Reviewed Flow Models 4.1 Method of Characteristics 4.2 Numerical Solution Procedures 4.2.1 Introduction to Finite Difference Methods 4.2.2 Mathematical Principles of Finite Difference Methods 4.3 Analytical Solution Procedures 4.4 Discussion of the Reviewed Solution Procedures 4.5 Summary and Conclusions 5 Novel Analytical Solution Approaches for the Zero-Inertia Equations 5.1 Novel Analytical Solution Approach for Zero-Inertia Open Channel Flow 5.1.1 Governing Equations 5.1.2 Including Nonprismatic Channel Geometries 5.1.3 Boundary and Initial Conditions 5.1.4 Analytical Solution of the Momentum Equation 5.1.5 Analytical Solution of the Continuity Equation 5.1.6 Algorithm for the Iterative Solution of the Nonlinear Problem 5.1.7 Coupling Surface Flow and Infiltration 5.1.8 Additional Remarks 5.2 Novel Analytical Solution Approach for Zero-Inertia Overland Flow 5.2.1 Governing Equations 5.2.2 Boundary and Initial Conditions 5.2.3 Analytical Solution 5.2.4 Algorithm for the Iterative Solution of the Nonlinear Problem 5.3 Summary 6 Comparative Studies with Generally Accepted Approaches 6.1 Open Channel Flow in Prismatic and Nonprismatic Permeable Open Channels 6.1.1 Test Setup 6.1.2 Comparison of Flow Dynamics 6.1.3 Analysis of the Geometry Parameter Sensitivity 6.1.4 Evaluating the Stability of the Analytical ZI Model 6.1.5 Summary 6.2 Overland Flow on a Plane 6.2.1 Test Setup 6.2.2 Comparison of Modeling Results 6.2.3 Summary 7 Flash Flood Routing under Transmission Losses and Dam Operation 7.1 Outline of the Structure of a Novel Integrated Modeling System 7.1.1 Wadi Flow Routing Models 7.1.2 Dam Simulation Model with Evaporation Component 7.2 Real-World Application of the Modeling System for an Arid Region 7.2.1 Study Area and Available Data 7.2.2 Parameter Sensitivity Analysis 7.2.3 Optimization-Based Process Parameter Estimation 7.2.4 Model Application for Wadi Ma\\\\\\\'awil 7.3 Summary 8 Summary and Conclusions 9 Outlook 9.1 The Modeling System for Improving Water Resources Assessment 9.2 The Modeling System for Optimizing Groundwater Recharge Bibliography A Mathematical Supplements A.1 Explicit First-Order Finite Difference Scheme for the Kinematic Wave Model A.2 Explicit Second-Order Finite Difference Scheme for the Kinematic Wave Model A.3 Implicit Finite Difference Scheme with Interior Point (Preissmann Scheme) A.4 Analytical Solution of the Kinematic Wave Model A.5 Details on the Derivation of the Iterative Procedure (5.47);(5.48) A.6 Details on the Evaluation of Equation (5.60) B Selected Publications of the Author B.1 Analytical Model of Surge Flow in Nonprismatic Permeable Channels B.2 Analytical Model of Surface Flow on Hillslopes B.3 Integrated Modeling System for Flash Flood Routing in Ephemeral Rivers / Diese Dissertation präsentiert einen neuartigen analytischen Lösungsansatz für das beschleunigungsfreie Wellenmodell (bzw. „Zero-Inertia-Modell“, „ZI-Modell“, oder „diffusives Wellenmodell“). Im Rahmen der Arbeit wird das hergeleitete hydrodynamische Modell sowohl zur Simulation von Freispiegelabflüssen in nichtprismatischen und durchlässigen Gerinnen, als auch für die Beschreibung von auf der Landoberfläche abfließendem Infiltrationsüberschuss eingesetzt. Es wird gezeigt, dass der neuartige analytische Ansatz — im Hinblick auf Massenerhaltung und die exakte Abbildung der Abflussdynamik — akkurate Ergebnisse liefert und gleichzeitig unter komplexen und verwickelten Prozessbedingungen anwendbar ist. So belegt eine vergleichende Analyse mit validierten numerischen Lösungsansätzen die Robustheit des analytischen ZI-Modells. Insbesondere die im Sinne der numerischen Mathematik stabile und genaue Modellierung der gekoppelten Abfluss- und Infiltrationsvorgänge in anfänglich trockenen Gerinnen ist dabei ein Novum. Weiterhin wird die Eignung und Anwendbarkeit des neuartigen Modellansatzes zur Beschreibung der Abflusskonzentrationsprozesse gezeigt. Der neuartige Lösungsansatz wird im Folgenden für ein reales Wassermanagementproblem im Sultanat Oman, Arabische Halbinsel eingesetzt. Als Bestandteil eines integrierten Modellsystems, welches ebenfalls im Rahmen der Dissertation vorgestellt wird, dient das analytische ZI-Modell zur Simulation von infiltrierendem Wadiabfluss, welcher unterstrom von Grundwasseranreicherungsdämmen starke Verluste von Masse und Impuls erfährt. Zusammen mit maßgeschneiderten und dem Stand der Technik entsprechenden Komponenten für die Betriebssimulation des Anreicherungsdammes (inklusive Verdunstung von der freien Seefläche) sowie für die Abbildung der oberstromigen hydrodynamischen Prozesse (ebenfalls inklusive Infiltration) wird der neuartige analytische Ansatz in einem Modellsystem zusammengefasst. Das Modellsystem ist in der Lage ein realistisches Bild der raumzeitlichen Dynamik des Abflusses sowie der Grundwasserneubildung aus infiltrierendem Wadiabfluss zu liefern. Damit stellt das Modellsystem ein wertvolles Werkzeug sowohl zur Wasserdargebotsermittlung, als auch für die Optimierung des Betriebes von Grundwasseranreicherungsdämmen dar.:List of Figures List of Tables List of Algorithms List of Symbols and Acronyms 1 Introduction 1.1 The Role of Ephemeral River Flow for Groundwater Recharge 1.2 Methods for Estimating Groundwater Recharge 1.3 Groundwater Augmentation Techniques and the Involved Processes 1.4 The Role of Overland Flow for Flash Flood Formation 1.5 Objectives of the Thesis 1.6 Structure of the Work 2 Literature Review 2.1 Surface-Water Based Studies on the Estimation of Indirect Recharge 2.2 Review of Literature on Process-Oriented Overland Flow Modeling 2.3 Summary 3 Principles of Physically-Based Modeling of Infiltrating Free Surface Flows 3.1 Hydraulic Phases of an Infiltrating Flow Event 3.2 Hydrodynamic Models 3.2.1 The Saint-Venant Equations 3.2.2 Zero-Inertia Approximation 3.2.3 Kinematic Wave Approximation 3.2.4 Other Simplifications of the Full Hydrodynamic Model 3.3 Initial and Boundary Conditions 3.4 Relating Friction and Flow Properties 3.5 Accounting for Losses or Gains 3.6 Including Arbitrary Cross-Sectional Geometries 3.7 Discussion of the Reviewed Flow Models 3.7.1 Discussion of Modeling Approaches for Ephemeral River Routing 3.7.2 A Suitable Hydrodynamic Model for Overland Flow 3.7.3 On the Portrayal of Shocks with the Kinematic Wave Model 3.8 Summary 4 Solution Procedures for the Reviewed Flow Models 4.1 Method of Characteristics 4.2 Numerical Solution Procedures 4.2.1 Introduction to Finite Difference Methods 4.2.2 Mathematical Principles of Finite Difference Methods 4.3 Analytical Solution Procedures 4.4 Discussion of the Reviewed Solution Procedures 4.5 Summary and Conclusions 5 Novel Analytical Solution Approaches for the Zero-Inertia Equations 5.1 Novel Analytical Solution Approach for Zero-Inertia Open Channel Flow 5.1.1 Governing Equations 5.1.2 Including Nonprismatic Channel Geometries 5.1.3 Boundary and Initial Conditions 5.1.4 Analytical Solution of the Momentum Equation 5.1.5 Analytical Solution of the Continuity Equation 5.1.6 Algorithm for the Iterative Solution of the Nonlinear Problem 5.1.7 Coupling Surface Flow and Infiltration 5.1.8 Additional Remarks 5.2 Novel Analytical Solution Approach for Zero-Inertia Overland Flow 5.2.1 Governing Equations 5.2.2 Boundary and Initial Conditions 5.2.3 Analytical Solution 5.2.4 Algorithm for the Iterative Solution of the Nonlinear Problem 5.3 Summary 6 Comparative Studies with Generally Accepted Approaches 6.1 Open Channel Flow in Prismatic and Nonprismatic Permeable Open Channels 6.1.1 Test Setup 6.1.2 Comparison of Flow Dynamics 6.1.3 Analysis of the Geometry Parameter Sensitivity 6.1.4 Evaluating the Stability of the Analytical ZI Model 6.1.5 Summary 6.2 Overland Flow on a Plane 6.2.1 Test Setup 6.2.2 Comparison of Modeling Results 6.2.3 Summary 7 Flash Flood Routing under Transmission Losses and Dam Operation 7.1 Outline of the Structure of a Novel Integrated Modeling System 7.1.1 Wadi Flow Routing Models 7.1.2 Dam Simulation Model with Evaporation Component 7.2 Real-World Application of the Modeling System for an Arid Region 7.2.1 Study Area and Available Data 7.2.2 Parameter Sensitivity Analysis 7.2.3 Optimization-Based Process Parameter Estimation 7.2.4 Model Application for Wadi Ma\\\\\\\'awil 7.3 Summary 8 Summary and Conclusions 9 Outlook 9.1 The Modeling System for Improving Water Resources Assessment 9.2 The Modeling System for Optimizing Groundwater Recharge Bibliography A Mathematical Supplements A.1 Explicit First-Order Finite Difference Scheme for the Kinematic Wave Model A.2 Explicit Second-Order Finite Difference Scheme for the Kinematic Wave Model A.3 Implicit Finite Difference Scheme with Interior Point (Preissmann Scheme) A.4 Analytical Solution of the Kinematic Wave Model A.5 Details on the Derivation of the Iterative Procedure (5.47);(5.48) A.6 Details on the Evaluation of Equation (5.60) B Selected Publications of the Author B.1 Analytical Model of Surge Flow in Nonprismatic Permeable Channels B.2 Analytical Model of Surface Flow on Hillslopes B.3 Integrated Modeling System for Flash Flood Routing in Ephemeral Rivers