Modelling Scour in Front of Dune Revetments in a Surf-beat Model

This paper presents adaptations to the XBeach model aimed at including the relevant processes for the generation of scour holes at the toe of a revetment. Dutch assessment rules for the safety of sea defenses need to be adjusted to cope with a combination of sandy dunes and hard elements. To that end, the XBeach model is prepared to be...

Falling aprons at circular piers under currents

Traditional guidelines on rock protection at circular piers predominantly focus on preventing shear failure (by choosing a sufficiently large rock size), winnowing failure (by designing an appropriate filter) and edge failure (by selecting a sufficient extent). In particular areas (e.g. in an eroding river channel or in an area with large-scale...

Physical modelling of san-filled geosystems for coastal protection

Unidirectional irregular waves of varying significant wave-height and peak period but with a constant spectral shape (JONSWAP spectrum, ?=3.3) were generated over a sandy 3:20 sloped plane beach to investigate scour fronting a dune erosion control system constructed from geotextiles, slope inclined at 45º. Both passive (i.e., three dune erosion...

Comparison of water jets and conventional propeller jets

Conventional ship propulsion systems and hydro jets differ in many ways. However, they are both responsible for sailing and manoeuvring of ships in a forward or reverse direction. The hydrodynamic jet is what they have in common, but the characteristics of the jets differ. For example, the outflow velocity of hydro jets is much higher than the...

Scour around an offshore windturbine

During the construction of the first Dutch offshore wind farm prototype measurements were performed. These measurements were aimed to monitor the behaviour of the granular filter layer of the scour protection around the mono-piles upon which the wind turbines are founded. These measurements were compared to scale model test results and...

Uncertainties in the design of bed protections near quay walls

Design formulas for bed protections in the port of Rotterdam were investigated. Using depthsoundings, the actual level of stability of a quay wall can be compared with the design formulas. The loads on a bottom protection differ, because of diversity in shipping and tidal motion. Therefore a better comparison can be made by resembling the...

The design and application of scour anticipated designs in river related and coastal structures in various countries and their effectiveness

Keynote lecture at the ICSE2006. Various types of scour can confront the engineer, who has to design and construct a hydraulic structure in a marine environment. The engineer is interested in the magnitude of the scour to be expected and its development in time. He hopes that such information, if at all available, is accurate and that he can...

The influence of upstram turbulence on local-scour holes

Excessive local scour can progressively undermine the foundation of a structure. Because complete protection against scour is too expensive generally, the maximum scour-depth and the upstream slope of the scour hole have to be predicted to minimize the risk of failure. In 1961 a systematical research 'tY'ith respect to scour holes started in the...