Open granular filter layers are widely applied in bed, bank, and shore protections to reduce hydraulic loads on underlying materials and geotextiles. While traditional design approaches primarily focus on mechanical stability, the transmission and damping of turbulent pressure fluctuations within these filters remain insufficiently understood. This is particularly relevant for the application of natural geotextiles, which are more permeable and mechanically weaker than synthetic alternatives and are therefore more sensitive to fluctuating hydraulic gradients.
This thesis experimentally investigates the propagation and attenuation of turbulent- and wave-induced pressure fluctuations through open granular filter layers, with the objective of validating and extending the spectral framework proposed by Thomas (2023). Physical experiments were conducted in the Hydraulic Engineering flume at Delft University of Technology using filters with thicknesses of 4, 6, and 8 cm. Two vertically aligned pressure sensor arrays were embedded at the top and base of the filter layer, enabling direct measurement of internal pressure fluctuations under both current-driven and wave-induced conditions across a range of flow velocities and water depths.

Pressure time-series were processed using advanced filtering techniques and transformed into power spectral densities. Temporal spectra were converted to spatial (wavenumber) spectra using a convection-velocity-based approach, allowing the damping of pressure fluctuations and the resulting hydraulic gradients to be analysed both per wavenumber and through integrated variance.
The results show broad agreement with the theoretical spectral shape predicted by Thomas (2023), particularly under highly turbulent flow conditions. Damping is found to be primarily governed by geometric parameters, notably the filter thickness and the ratio between water depth and filter thickness (h/D_f). Thicker filters and shallower water depths lead to significantly stronger attenuation of turbulent fluctuations. Flow velocity mainly influences the absolute magnitude of the hydraulic load but does not affect damping efficiency. In contrast, wave-induced pressure fluctuations, characterised by low wavenumbers, experience only limited damping within the filter layer.

By quantifying both spectral damping and transmitted hydraulic loads, this study provides a physical basis for incorporating load-type dependency and geometric scaling into filter design. The findings support more reliable and sustainable design approaches for granular filters and contribute to the safe application of natural geotextiles in hydraulic engineering.
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This report, titled Expanding Puerto Rawson: Enhancing Fishery Capacity and Project Cargo Logistics, presents a conceptual masterplan for the eco-friendly expansion of the Port of Rawson. The port’s proximity to a region abundant in marine resources makes it an attractive location for expansion. However, the port is facing strategic expansion problems and it could fail to accommodate the rise in demand from the fishery industry. This report carefully maps out the gap between the expected rise in demand and the currently existing infrastructure. After that, two models are created to transform the rise in demand that is expected by 2030 & 2040, to nautical demands for the port, like number of berths and required waterway width. The results from these model in combination with a strategic overview of the landscape, were used to come up with three conceptual designs that eventually converged into one final conceptual design by conducting an MCA. This conceptual design, together with the port waste management plan, could enable an eco-friendly and future-ready expansion of the Port of Rawson. ... Read more