Bed-load transport over inlet sills of longitudinal training walls: Experimental study

This experimental study is about the bed-load transport over inlet sills of longitudinal training walls. The focus is on the flow structures around the inlet: the shape, the processes and the effect on sediment transport. Groynes have been replaced by longitudinal training walls in an 11-km long pilot project to optimize training of the river...

Tidal Bridge Dynamics: Optimising the dynamic response due to wind, waves and current

Currently, there is no infrastructure between the two Indonesian islands Flores and Adonara. The islands are separated by the Larantuka Strait, which has a width varying between 600 and 1000 meters. The local government would like a bridge between the two islands. However, as the water in the 18 meter deep strait is heavily subjected to tidal...

Scour hole formation for lateral non-uniform flow in non-cohesive sediments

For a project in the province of Zeeland, The Netherlands, a culvert was installed trough a dike to restore the tidal flow. Shortly after commissioning of the facility a scour hole at the end of the bottom protection developed. Although the scour hole was anticipated in the design, the scour hole was developing more rapidly than predicted....

Stability of randomly placed log bed protections

Design criteria for the stability of rock filters on river beds (i.e. rock bed protection) are extensively researched and successfully applied in practice. The most common stability criteria are the Izbash and Shields criteria. These methods define a critical flow (Izbash) or parameter (Shields). Rijkswaterstaat (RWS) wants to explore a more...

Flow over and around submerged groynes: Numerical modelling and analysis of a groyne flume experiment

In submerged conditions groynes add resistance to a river, thereby increasing the water levels for a particular discharge. Groynes are modelled in two ways, either they are included in the bed topography when the grid resolution is sufficiently high or with a sub-grid parametrisation when the grid cell-size is larger than the geometry of the...

The Submerged Floating Tunnel: An experimental study on the hydrodynamics and kinematics of a submerged rectangular cylinder in a wave-current environment

This study presents the results of small scale flume experiments on a submerged rectangular cylinder subjected to a current, regular wave and combined wave-current environment. The objective of the study is to gain more knowledge about the hydrodynamics around and the kinematics of a submerged structure, to give a contribute to the research...

The influence of surface screens on morphology in side channels

Following from the programme Room for the River, side channels are created in the Netherlands. For their maintenance, alternatives to dredging vessels are needed because of nature development, such as surface screens, that use the flow itself to generate erosion. <br/>A field experiment using surface screens was executed at the small side...

Porcupines for river training: A study on the near-field effect of porcupines

Braiding rivers are characterised as highly dynamic, and experience annual morphological changes in plan- form. This dynamic nature of the river leads to navigational hindrance and risk of unstable bifurcation points where discharge distributions might switch. In pilot studies, porcupines have shown promising results in re- tarding the flow and...

The prediction of stone stability by a three-dimensional eddy resolving simulation technique

In this thesis, it is studied if the stability of a stone in a granular bed protection, can be predicted by the local output of a three-dimensional (3D) eddy resolving simulation technique.<br/><br/>In earlier studies regarding stone stability, Reynolds-Averaged Navier-Stokes (RANS) models are used to determine the loads on the bed. In the...

Experimental research on channel closure in braided rivers

The dynamic nature of braided rivers can lead to river bank erosion, bankline shifts and navigational hindrance. River training measures can be implemented in order to mitigate these problems. An alternative to conventional river training works is the closure of a channel within the braided network. Until recent there has been no systematic...

The effects of vegetation on riverbank stability in the Ayeyarwady River: The use of the Normalised Difference Vegetation Index as indicator for stabilising effects of vegetation by measuring bank retreat rates

The Ayeyarwady River is the most important river in Myanmar, connecting the cities Mandalay and Yangon, making inland water transport economically attractive. The Ayeyarwady River has a dynamic character, caused by the significant discharge difference between the dry and rainy season, and the related suspended sediment transport. Point bar...

Stability of stones on mild slopes

The static stability of stones on mild slopes under wave attack is investigated in this research. The first part of the research is focused on reproducing the physical scale model tests regarding profile change of Kramer (2016) numerically with the model XBeach-G. The erosion profiles modelled with the bed-load transport formulas of Nielsen ...

The influence of hydropower developments on the Mekong delta

Rapid hydropower development is taking place in the Mekong river, which is expected to change the natural river regime. Because of the ecological and economical importance of the Mekong delta, the effects of these changes could have large consequences in the delta area. This research focuses on the hydrodynamical processes and assesses potential...

Implications of Fine Sediment Dynamics in Relation to Flushing Operations for Physical Habitats at the Meso-scale

Worldwide, dam reservoirs loose over one percent of their storage capacity every year due to sedimentation. Proper management is therefore urgent. While drawdown flushing is considered an effective method to remove sediments from the reservoir, the increased sediment flux has an impact on the downstream environment. On the short term, several...

The influence of vegetation on flow and transport mechanisms: An experimental study on sediment transport mechanisms in two parallel stretches of vegetated and non-vegetated bed

Vegetation on river banks and bars contribute to the stability of these morphological features; however, the exact processes that contribute to this stabilization are still subject to research. This study has looked into the flow phenomena at the streamwise interface between a vegetated and non-vegetated river bed. Flow velocities in vegetated...

Stability of block mattress under non-uniform flow downstream of sluice gate

Downstream of hydraulic structures, the flow is normally of turbulence. This will cause considerable erosions on the gravel bed. To prevent this, block mattress is preferable in many cases. Its effective stabilization and feasibility on construction make it commonly used against scouring problems, protecting underwater pipelines and cables. The...

A new physics-based method for estimating the excess turbulence downstream of a structure

Erosion and sedimentation are natural processes that occur in natural flows.<br/>If the erosion is a threat for a structure, a bed protection is necessary to stop this process. A bed protection usually consists of relatively large stones.<br/>For calculating the required dimeter of the stones several formulae are available, of which the formula...

Physical Scaling of Tocardo’s Eastern Scheldt Turbines: Additional Graduation Work

Additional thesis - The largest structure of the Dutch Delta Works, that protect the Netherlands against high water levels at sea, is the Eastern Scheldt storm surge barrier. The Eastern Scheldt barrier is constructed as an<br/>open structure that can separate the Eastern Scheldt estuary from the North Sea. In case that water<br/>levels of +3.00...