Repository for Publications and Research Data

Submit

Manual

Discover new chapters.

ETH Library

News from the ETH Library

Recently Added

Umsetzung von Keyline Design auf Schweizer Landwirtschaftsbetrieben: Praktische Erfahrungen und Entwicklung eines Leitfadens

Master Thesis

Waldner, Sandrine (2026)

Keyline Design ist eine Methode, mit der Niederschlagswasser länger auf einer Fläche zurückgehalten und gezielt verteilt werden kann. Durch das Keyline Design kann Wasser wieder auf Hügelkuppen geleitet werden, wo es unter natürlichen Bedingungen am schnellsten abfliesst und die Standorte häufig am trockensten sind. Zudem trägt das System zur Reduktion von Erosion, zum Humusaufbau sowie zur Förderung der Biodiversität bei und kann die Resilienz landwirtschaftlicher Betriebe gegenüber dem Klimawandel erhöhen. Vor dem Hintergrund des Klimawandels nehmen Niederschlagsereignisse in ihrer Intensität zu, während ihre Häufigkeit abnimmt. Gleichzeitig verschiebt sich der Wasserabfluss zunehmend vom Sommer in den Winter, da weniger Schnee fällt und entsprechend weniger Schmelzwasser anfällt. Methoden zur Rückhaltung von Niederschlagswasser und zum Erhalt der Bodenfeuchtigkeit gewinnen daher in der Landwirtschaft zunehmend an Bedeutung. Diese Arbeit untersucht anhand von vier Praxisbeispielen im Jurapark Aargau die praktische Umsetzung von Keyline Designs auf Schweizer Landwirtschaftsbetrieben und entwickelt einen möglichen Leitfaden zur Planung und Implementierung solcher Systeme. Analysiert wurde, wie unterschiedliche Betriebe Keyline Designs an ihre jeweiligen Betriebsstrukturen und Bewirtschaftungsziele anpassen. Die Ergebnisse zeigen, dass Keyline Designs stark betriebsspezifisch sind und unterschiedliche Landnutzungen wie Ackerflächen, Hochstammobstbäume, Haselnussbäume oder Futterhecken integrieren können. Auf Grundlage der gewonnenen Erkenntnisse wurde ein Prozessablauf für die Planung von Keyline Designs zusammengestellt. Daraus wurden praxisnahe Leitfäden in Form einer Checkliste und einer Canvas entwickelt. Diese Instrumente sollen die Planung unterstützen, eine Übersicht über relevante Aspekte ermöglichen und potenzielle Wissenslücken sichtbar machen. Eine Evaluation der Praxistauglichkeit durch Landwirtinnen und Landwirte steht noch aus, bietet jedoch Ansatzpunkte für zukünftige Weiterentwicklungen. Die Arbeit zeigt, dass Keyline Designs in der Schweiz ein flexibles und anpassbares Instrument darstellen, das ökologische Vorteile bieten kann. Gleichzeitig verdeutlicht sie den Bedarf an praxisorientierten Hilfsmitteln sowie an weiterer Forschung, um die Implementierung zu erleichtern und den Nutzen für landwirtschaftliche Betriebe und die Umwelt fundiert aufzuzeigen.

Development of a Low-Cost Ultrasound Flow Sensor

Master Thesis

Scettrini, Samuele (2026)

Accurate monitoring of emission reduction projects is essential to ensure the environmental integrity of carbon crediting mechanisms established under the Paris Agreement. In biodigester-based clean cooking projects, monitoring is often based on survey data, which is prone to systematic overestimation and may lead to over-crediting. Direct measurement of biodigester usage through low-cost sensing offers a promising alternative; however, existing gas flow and composition sensors are typically too expensive for large-scale deployment in decentralized settings. This thesis presents the design, implementation, and evaluation of a low-cost transit-time ultrasonic flow meter intended for biogas applications. The proposed sensor measures volumetric flow rate and estimates gas composition by combining bidirectional ultrasonic time-of-flight. The system integrates commercially available components on a custom printed circuit board and is calibrated using controlled air and CH4–CO2 gas mixtures representative of field conditions. Experimental results demonstrate that, for air, the sensor achieves a mean relative error below 3 % over a flow range of 2–10 L min−1. For biogas-like mixtures with methane concentrations between 70 % and 100 %, gas composition can be estimated with a mean relative error below 1 %, while volumetric flow rate errors increase substantially due to ultrasonic signal attenuation in CO2-rich environments. At methane concentrations below 70 %, reliable measurements are not achievable with the adopted architecture. The total estimated production cost of the prototype is approximately 36 CHF, significantly lower than that of commercially available ultrasonic flow meters. The results highlight both the potential and the limitations of low-cost transit-time ultrasonic sensing for biogas monitoring. While the proposed sensor is suitable for applications involving high methane concentrations, extending its operational range to CO2-rich mixtures will require more advanced signal acquisition and processing techniques. Future work should therefore focus on ADC-based ultrasonic measurement approaches that offer improved robustness under low signal-to-noise conditions

Investigating the connection between superhydrous melts, magma reservoir nucleation and the scarcity of mafic eruptions in post-collisional settings

Journal Article

Näpflin, Alissa; Popa, Răzvan-Gabriel; Seghedi, Ioan; et al. (2026)

Journal of Volcanology and Geothermal Research

Magma reservoir emplacement in the brittle upper-crust typically requires prolonged heating to modify host-rock rheology, allowing magma to accumulate rather than erupt. In thermally immature crust, early eruptions are expected to be mafic, yet many volcanic provinces, particularly those with water-rich melts, lack significant initial mafic volcanism, suggesting an alternative trapping mechanism. We investigate this using Caraci volcano (Romania's Apuseni Mountains), a water-rich system that started with relatively differentiated, andesitic eruptions. The first eruptions at Caraci extruded water-rich (5–6 ± 0.35 wt% dissolved H₂O) amphibole-plagioclase andesites (890–920 ± 22 °C) stored at water-saturated conditions in the upper-crust (∼2 ± 0.5 kbar). These magmas were associated with superhydrous primitive melts (>6 wt% H₂O), which evolved in a polybaric system (crystallization pressure varying from 2 to 8 ± 0.5 kbar), evidenced by high-Mg amphibole and delayed plagioclase crystallization. These deeper storage melts likely reached water saturation during ascent towards the upper crust, inducing degassing and crystallization, which increased viscosity and enabled stalling in the cold crust, explaining the lack of initial mafic eruptions and providing the efficient trapping mechanism in a thermally immature crust. Progressive drying of the source and generation of less hydrous magmas initiated the eruptions and construction of the stratovolcano, and ultimately terminated the system. As a result, the final eruption extruded somewhat drier (4–4.5 ± 0.35 wt% H₂O), hotter (930–960 ± 45 °C) pyroxene-bearing andesites erupted from water-undersaturated storage. This trapping mechanism of water-rich magmas may explain the typical scarcity of mafic volcanism in arc and post-collisional settings.

Regulation of the γ-Tubulin Ring Complex by the Centrosomal Proteins CDK5RAP2 and NEDD1

Doctoral Thesis

Xu, Yixin (2026)

Impact of non-1D Earth on FDEM measurements and the performance of PWI and LCI Inversions

Journal Article

Carrizo Mascarell, Maria; Werthmüller, Dieter; Slob, Evert (2026)

Journal of Applied Geophysics

Subsurface electrical conductivity models from frequency-domain electromagnetic (FDEM) induction measurements are often derived using computationally efficient one-dimensional piecewise inversion (PWI) approaches. However, PWI does not account for lateral conductivity variations or the measurement overlap between adjacent soundings, which can limit model estimation accuracy. Laterally constrained inversion (LCI) introduces smoothness constraints to reduce lateral variability between neighbouring models, potentially improving continuity. In this study, both PWI and LCI use a 1D forward function, assuming a horizontally layered earth, and a horizontally laying rigid boom instrument, to perform the estimations This study presents a detailed analysis of how various 2.5D and 3D conductivity distributions, including topographic variations and instrument pitch angle, affect FDEM measurements. We examine how these measurement distortions propagate into PWI and LCI inversion results. Under ideal conditions, such as flat terrain, no instrument tilt, and simple two-layer models, both methods recover accurate conductivity structures, with LCI offering little advantage in accuracy. When topography is introduced, however, distortions occur even at slopes as small as 2°, and both methods show degraded performance, particularly in 3D scenarios. In the field example, LCI produces smoother and more stable results than PWI in the presence of noise, but its assumption of lateral smoothness can be restrictive in geologically complex settings. Our findings show that both inversion strategies are sensitive to topographic and 3D effects, and that error propagation significantly influences inversion reliability. These results highlight the need for improved methodologies capable of handling realistic acquisition conditions and measurement uncertainties in FDEM surveys.