Jet scour

This paper discusses scour without bed protection, such as propeller scour, two-dimensional horizontal, three-dimensional horizontal scour generated by free jets downstream of gates and outlets, two-dimensional vertical and three-dimensional vertical scour. The flow velocities in two- and three-dimensional propeller and free jets are briefly...

Shear stress concept in granular filters

Scour is a natural phenomenon caused by the flow of water in rivers and streams and occurs as a part of the morphological changes caused by rivers or as a result of man-made structures. For the Dutch Delta Works hydraulic structures were often constructed on fines with loose packing. To guarantee the geotechnical stability of these structures...

Ontgrondingen rondom brugpijlers en aan de kop van kribben

Het doel van het handboek ontgrondingen is een antwoord te geven op ontgrondingsvraagstukken zoals een ontwerper van waterbouwkundige constructies die tegenkomt. Verschillende deelstudies worden voor het afronden van dit handboek uitgevoerd. Het verifiëren van ontgrondingsformuies staat centraal in deze studies. Hier is de voorspellingskracht...

Ontgrondingen door ondergedompelde stralen

Het doel van het handboek ontgrondingen is een antwoord te geven op ontgrondingsvraagstukken zoals een ontwerper van waterbouwkundige constructies die tegenkomt. Verschillende deelstudies worden voor het afronden van dit handboek uitgevoerd. Het verifiëren van ontgrondingsformules staat centraal in deze studies. Hier is de voorspellingskracht...

Ontrondingen door vallende stralen

Het handboek ontgrondingen beoogt een instrument te zijn om de grootte van lokale ontgrondingskuilen rondom brugpijlers, kribben, achter drempels met of zonder bodembescherming, uitlaatconstructies, strandmuren, strandhoofden, etc. te voorspellen. Met het handboek kunnen ontwerpers en adviseurs een eerste schatting van het ontgrondingsproces...

A hydraulic and morphologic criterion for upstram slopes in local-scour holes

Scour is a natural phenomenon caused by the flow of water in rivers and streams. Scour occurs naturally as part of the morphological changes of rivers and as result of structures man-made. Several types of scour can be distinghuished. Experience has shown that due to sand or flow slides or micro instabilities at the end of the bed protection,...

A study concerning the influence of the relative local turbulence on local-scour holes

Scour is the lowering of the sea or river-bed as a result of non-equilibrium sediment transport conditions and can be divided into several categories (Breusers and Raudkivi, 1991). Local scour, which may occur at the base of a structure because of the affected flow pattern, can severely endanger the stability of this structure. Many varieties of...

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...

Users manual: DUCT-SUSTRA

Some information is given how to use the scour model DUCT-SUSTRA (Hoffmans, 1991). The scour model predicts the morphological process in scour holes or trenches and consists of two separated sub-models: a flow model DUCT and a morphological model SUSTRA. The flow model is based on the equation of continuity and the momentum equations for...

Concentration and flow velocity measurements in a local scour hole

Flume experiments with small Froude numbers have been carried out to study the concentration field in a local scour hole without supply of sediment load. The measuring results will be used to check the validity of the two dimensional scour model DUCT-SUSTRA. The objective of the experiments was to measure the concentrations at various locations...