Groyne

About: Groyne is a research topic. Over the lifetime, 397 publications have been published within this topic receiving 4549 citations. The topic is also known as: groin & Breakwater.

Beach and dune nourishment in the netherlands

Abstract: In the Netherlands up to the fifties of this century, dike and groyne building were the most important coastal defence measures Because of the increased awareness of the importance of the sandy coast the demand for a more environmentally friendly coastal protection measure increased However, artificial beach nourishment was very expensive In the past two decades the costs of nourishment have decreased as a result of technical developments in the dredging industry, and erosion control by means of sandfills has become in general cheaper than the construction of groynes and dikes In that period also large volumes of sand have become available from harbour extension and maintenance dredging These have been the conditions that led to a new coastal defence method Up till now nearly 50 beach nourishment projects have been carried out, with a total amount of 60 million m This paper provides a review of the projects carried out in the last 4 decades, with a description of the most important aspects

Modelling shoreline evolution in the vicinity of a groyne and a river

Abstract: Analytical solutions to the equations governing shoreline evolution are well-known and have value both as pedagogical tools and for conceptual design. Nevertheless, solutions have been restricted to a fairly narrow class of conditions with limited applicability to real-life situations. We present a new analytical solution for a widely encountered situation where a groyne is constructed close to a river to control sediment movement. The solution, which employs Laplace transforms, has the advantage that a solution for time-varying conditions may be constructed from the solution for constant conditions by means of the Heaviside procedure. Solutions are presented for various combinations of wave conditions and sediment supply/removal by the river. An innovation introduced in this work is the capability to provide an analytical assessment of the accretion or erosion caused near the groyne due to its proximity to the river which may act either as a source or a sink of sediment material.

Beach fill at two coasts of different configurations

Abstract: Movements of borrow sand replenished at two coasts of different configurations are investigated by analyzing the topographic data which were surveyed periodically after the beach fill placements. One is a long straight beach and borrow sand was placed behind a submerged breakwater. Another is a pocket beach which has an arcshoreline with a groyne at one end and a headland at another. It is found that the amount of borrow sand moved in the longshore direction surpasses the amount of borrow sand transported in the cross-shore direction regardless of the shape of the coast. A clear correlation is also found between displacements of shoreline and changes of sectional areas. These results imply that the deformation of the artificially nourished beach and the dissipation rate of borrow sand can be predicted by the so-called one-line theory.

The modular habitat model (MHM) for the ide, Leuciscus idus (L.) ‐ a new method to predict the suitability of inshore habitats for fish

Abstract: Summary Groynes are the dominant river engineering structures along the lowland section of large European rivers such as the Rhine, Danube and the Elbe. More than 6000 groynes structure the 400 km stretch of the potamal of the Elbe River. After 1945, destruction of the groynes increased through ice and flood events in the eastern part of Germany. In the past ten years, groyne reconstruction was accompanied by a controversial discussion in the context of the ecological integrity of the Elbe River. With the modular habitat model (MHM) a tool was developed to evaluate the suitability and to balance the availability of fish habitats in groyne fields of different conditions. The morphodynamic module produced a digital terrain model and a spatial model of flow velocity for each groyne field separately. Based on point abundance sampling by electro-fishing, models of habitat preference were developed for different life history stages by logistic regression. Statistical models predicting the preference of fish-environment relationships (Leuciscus idus) at different life history stages. The models were discriminated and validated by receiver operating characteristic (ROC) curves. The link between the statistical and the spatial model was realised in the suitability module. The suitability of microhabitats is expressed in classes for each species and life history stage separately. Habitat availability is balanced on the level of mesohabitat, e.g. different types of groyne fields. The temporal dynamics of habitat availability are analysed by considering different levels of discharge. For the stage ‘juvenile A’ and preadult the habitat suitability is better in fields downstream of destroyed groynes. For ‘juvenile B’ and adult stages of the ide, groyne fields in general constitute low habitat suitability. Differences in spatial availability are higher than the differences in temporal habitat availability.