Wave attenuation by flattened vegetation (Scirpus mariqueter)

With the capacity to reduce wave energy and trap sediment, Scirpus mariqueter has become an important native species of annual grass for ecology restoration at the Yangtze Estuary in eastern China. Due to seasonal variances of biophysical characteristics, S. mariqueter usually bends and breaks in winter, resulting in flattened stems that may...

Erosion Behavior of Sand-Silt Mixtures: Revisiting the Erosion Threshold

The erosion threshold, beyond which bed sediments start to move, is a key parameter describing sediment transport processes. For silt-dominated mixtures, in which the grain size is between sand and clay, existing experimental studies exhibit contradictory observations. That is, the erosion was either sand-like or clay-like, suggesting...

Retardation of breach growth under high flow velocities: Applicability of a bentonite-additive

People all around the world live and work in low-lying areas. Low-lying areas have to be protected against high water levels in rivers and at sea by a water protection system (e.g. by dunes, dikes and barriers). Dikes are an important component within water protection systems. Generally, dikes are described as elongated naturally occurring or...

A laboratory experiment on the evolution of a sand gravel reach under a lack of sediment supply

A flume experiment was conducted to examine the evolution of a sand-gravel reach under a lack of sediment supply. A bed composed of a bimodal sediment mixture was installed with a uniform slope and an gradual fining pattern. At the upstream end of the flume the initial bed consisted of 100% gravel, which decreased stepwise (10% steps) in...

Hydrodynamic Drivers of Sediment Transport Across a Fringing Reef

Coral reefs are highly valuable ecosystems, which are under an increasing number of environmental pressures. Sedimentation and sediment transport patterns are among key physical drivers of coral reefs, so it is important to improve our understanding of these poorly studied dynamics on reefs. To this purpose, flume experiments were performed on a...

Sediment transport in a fringing reef environment: Analysis using laboratory experiments and numerical modelling

Coral reefs are highly valuable structures in many respects and it is increasingly important to understand hydrodynamics and morphodynamics around reefs to be able to better protect them and their hinterland. Flume experiments were performed on a scaled fringing reef in the laboratory facilities of Deltares in Delft. The objective of this thesis...

Stability of open filter structures

Granular filters are used for protection against scour and erosion. For a proper functioning it is necessary that interfaces between the filter structure, the subsoil and the water flowing above the filter structure are stable. Stability means that there is no transport of subsoil material through the filter to the water above the filter, and...