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Experiments by Invited Researchers

 

Infiltration and ex-filtration on beach face

Project acronym: HyIII-FZK-06
Name of Group Leader: Leonardo Damiani, Technical University of Bari
User-Project Title: Infiltration and ex-filtration on beach face
Facility: Large Wave Flume, GWK
Proceedings TA Project: Swask zone hydrodynamic of a drained beach
Data Management Report: There is no Data Management Report available for this project

User-Project Objectives

Summary:

The project is aimed to analyse the effects of wave motion on the in- and ex-filtration processes on the beach, focusing on the water table oscillations in a beach with and without a drainage system, which can be used to stabilize the beach in the foreshore zone. Another aim of the experimental program is to evaluate the influence of the drainage system on the set-up and the run-up, analysing if the drainage system can modify the near shore hydrodynamics.

The main objective is to reduce all the uncertainties about scale effects, relevant in small scale movable bed models, and the uncertainties in recognizing a good analogy about the sand to reproduce rightly all the sediment characteristics (grain size curve, fall velocity, permeability) of the prototype.

In order to perform trials similar to the ones presented in literature, the experimental program in the GWK made possible not only the investigation of hydrodynamics processes in the near shore zone, but also gave some information about the morphological evolution due to drainage and about scale effects.

The tests done in the GWK led to results about hydrodynamic and morphologic aspects of the beach drainage system. Experimental results were achieved to study drainage effects on the evolution of the beach profile, under two different wave attacks and to define also the better position of the rains, in order to reduce beach erosion. All tests in the GWK were performed jointly in cooperation with the project HyIII-GWK-5.

It was possible to observe the different behaviours of the water table between two kinds of wave attacks, and to understand how the saturated zone develops when drains are working: the decrease of the saturated beach in the run up zone due to drainage may be assumed as an efficiency parameter of the drainage system.

In the undrained configuration it was interesting to evaluate the growing up of water table with the different wave conditions, and to compare it with the lowering of water table position due to drainage.

To analyze the interaction between wave motion and water table oscillation, with the measured data-set it will be possible to refer to wave spectrum, focusing if the frequency spectrum of the breaking wave on the shore influences the water table dynamics or not. A video technique used, allows analyzing the wave run up on the beach through study of recorded videos, captured images and topography surveys of the beach. The analysis of the velocity field, (obtained with electromagnetic velocity meters) allows investigating the influence of drainage system on the near shore currents.

At least, GWK experimental results will be compared with a small-scale data-set obtained at the LIC (Laboratory of Coastal Engineering), in order to evaluate scale effects.

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