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Foyers of Werkhotels bieden wonen, begeleiding en daarmee samenhangende voorzieningen op een locatie, bestemd voor jongeren in de leeftijdsgroep van 18 tot 25 jaar. Foyers kunnen varin in omvang van twintig tot een paar honderd bewoners, in het aanbod van voorzieningen en in de mate van openheid voor de omgeving. In Frankrijk en in het Verenigd Koninkrijk zijn in vijftig, respectievelijk twintig jaar honderden Foyers gerealiseerd, maar in Nederland komen Foyers moeizaam van de grond. Het onderzoek gaat in op de kenmerken van Foyers, de programmering van het bouwkundig ontwerp en de ontwikkeling en het beheer van Foyers en geeft de randvoorwaarden voor de Nederlandse situatie. Het programma van eisen valt uiteen in de woon- en gebruikswensen van de beoogde bewoners, van de begeleiders en beheerders, en van de externe betrokkenen zoals de omwonenden en de gemeente. Bij de ontwikkeling en het beheer zijn vele, soms tientallen partijen betrokken. Belangrijke onderscheidende aspecten van beheer zijn de organisatievorm, de wet-en regelgeving, het financieel beheer (inclusief de exploitatie) en het sociaal beheer. Tenslotte worden van de Nederlandse Foyers en de buitenlandse voorgangers succes- en faalfactoren benoemd. Dit onderzoek is een explorerend onderzoek. Allochtone jongeren zijn ruim vertegenwoordigd in de doelgroep, in de Nederlandse praktijk vormen Antilliaanse jongeren de grootste groep Foyerbewoners. De empirische dataverzameling is afkomstig van projecten in Nederland, Frankrijk, Engeland, Cura en Aruba. De grootste Nederlandse Foyer, Crabbehof in Dordrecht, is casestudy.

The Dutch Western Wadden Sea, comprising the basins of Texel, Eierlandse Gat and Vlie, suffers a shortage of sediments. This implies that sediment is imported into the basins. The influence of the main forcing agents on the sediment transport is investigated. These forcing agents are the tide, waves and wind. In case of the wind forcing, both the large-scale and local wind forcing are taken into account. The tide induces an import of sediments through the Texel inlet, and export through the inlets of Eierlandse Gat and Vlie. Waves have most influence on the ebb-tidal delta region of the inlets. Due to the sheltering effect of these deltas and the barrier islands they lose most of their energy when they enter the inlets. As a result the influence of the waves on the sediment transports inside the basins is low. Wind forcing generates a residual flow that is of the same order of magnitude as the residual flow generated by the tide. It induces residual sediment transports through the inlets that are of the same order of magnitude as the tide induced sediment transports. A wave and wind climate is constructed to determine the annual residual sediment transports. With the bathymetry of the year 1998, in total a volume of 6306*103m3/yr is imported into the basins. With the help of the semi-empirical equilibrium relations, the required volume of sediments for the basins to be in equilibrium is determined. In total a volume of 13.78*108m3 is added, 88% of this is placed in the Texel basin. As a result the transport through the Texel inlet approaches the equilibrium (little to no residual transport), but through the other two inlets there is a strong residual export. The shift of the tidal divides is one reason for these results. These divides shift towards the Texel inlet, adjusting the tidal propagation in the basins. In the basins of the Eierlandse Gat and Vlie this results in an increase of the exports. This effect was not taken into account with the determination of the required volume of sediments. Another reason for the strong export through the inlets of the Eierlandse Gat and Vlie is the placement of the added sediments. In the basins of these inlets the additional sediments are predominantly placed in the ebb-channels. This increases the residual export of sediment through these channels. This implies that the determined equilibrium bathymetry is not the exact equilibrium. Yet it gives a fair indication of the amount of sediments needed for the basins to be in equilibrium.

From the several existing empirical equations that describe the planform of a bay, the Parabolic Bay Shape Equation (PBSE) is the only one that explicitly assesses an equilibrium bay shape. Research has been performed on the uncertainties regarding the static equilibrium planform (SEP) plotted by this equation but results have been more of a qualitative nature. This paper is an attempt to quantify the uncertainty in the application of the PBSE using existing bays. By means of an expert elicitation, a database consisting of the position of the control points needed to plot the SEP was generated. The elicitation was held under experts in the field of coastal/hydraulic engineering and consisted of two parts. In the Part 1 of the elicitation, twenty-two expert volunteers where asked to place the three control points needed to draw the SEP on a vertical aerial photograph of Taquaras/Taquarinhas Bay, an stable bay, approximately 1800m wide and 750m indent, in the south of Brazil. The software program MEPBAY, which facilitates the use of the PBSE was used to translate the position of the control points into the SEP's corresponding to the bay. The distribution of the location of the SEP along four evenly spaced (200m) profiles in the southern part of the bay was determined. The overall bias of the location of the SEP calculated over the four profiles is in the order of 40m (landward) and the average bandwidth is 116 m. The bandwidth and standard deviation of the SEP increase when moving alongshore toward the curved section of the bay. This means that the uncertainty in the application of the PBSE is dependent on the particular point of interest along the bay. In Part 2 of the elicitation thirty volunteers participated. This time the consequence of the placement of the control points (the corresponding SEP) was visible. Comparing the results from Part 1 and 2, it was observed that when volunteers are directly confronted with the result of the placement of the control points (a plotted SEP) a much smaller variation in the position of the SEP occurs. This in turn means that the PBSE is a robust method provided the user sees the result of his/her choices in placement of the control points. After quantifying the uncertainty when applying the PBSE to a stable bay an unstable situation was analyzed. For this case the bay of Imbituba in southern Brazil was chosen. The construction of a breakwater to shelter the port of Imbituba in the south of the bay was accompanied by an increase in sedimentation of the port. Superimposed plots of the coastline of the bay of Imbituba from different years confirm a general trend of accretion of the southern part of the bay accompanied with a retreat of the coastline in the northern part. After the application of the PBSE it was clear that the breakwater caused a change in the equilibrium state of the bay. Between 1947 and 2001 the Bay of Imbituba has changed from a dynamic equilibrium to a close to static equilibrium in the northern part of the bay and an unstable equilibrium status in the southern part. The tendency of the sedimentation of the southern part of the bay can be explained by looking at the SEP belonging to the new up coast diffraction point (tip of the breakwater): The seaward position of the SEP predicts a need for sediment in order to achieve a stable planform.

In dit rapport wordt onderzocht hoe een woningcorporatie effecten van leefbaarheidsinvesteringen kan meten en evalueren

This Masters Thesis is a pilot research project in order to investigate which parameters, other than the wave energy density spectrum, could play a role in breakwater damage on variable foreshore steepness. The research project is based up on laboratory research, were for equal wave spectra at the toe of a coastal structure significantly more damage (order of 30%) occurs to a steep foreshore in contrast to a mild slope. In order to investigate which parameters, other than the parameters included in the wave energy density spectrum could play a role in the increase in damage for a steep foreshore, an experiment was conducted. In the wave flume of the Fluid Mechanics Laboratory an experimental test set up was constructed. The test setup consisted of a breakwater build on variable foreshore steepnesses (1:30, 1:15 and 1:8). Tests were conducted with regular waves, were the wavelength and the wave steepness at the toe of the breakwater were kept constant per individual test. These tests were conducted for the three different foreshore steepnesses. Wave runs were completed for different wave heights and wave steepnesses. Each experiment was repeated in order to increase the accuracy. At the breakwater the wave velocity and acceleration was measured with zero buoyant particles. The particles were monitored with a video camera. From these video images the velocity and acceleration relative to the breakwater slope were calculated. In order to check the accuracy a reliability study of the experiment was performed. The faults in the experiment were estimated and assumed to be normal distributed. The reliability of the entire experiment was calculated for velocity and acceleration measurements. The velocities and accelerations for up-rush and down-rush were compared for equal wave conditions and different foreshore steepnesses. The experimental data shows that the velocities for up-rush and down-rush are higher for waves travelling over a steep foreshore (order of 10%). Also the obtained accelerations for both up-rush and down-rush are higher for waves travelling over a steep foreshore. When the wave force is calculated with a Morrison equation, the increase in force due to the increase in velocity for waves travelling over a steep foreshore is in the order of 20%. When considering that the acceleration is also larger in this case, this results an even larger total wave force. By linking the wave force to the level of damage, it can be explained that for equal wave spectra at the toe and for variable foreshore steepness the largest damage was measured for waves travelling over a steep foreshore.

Stratified exchange flows driven by a density difference are found in many natural water bodies and in the atmosphere. A typical case in nature is the strait of Gibraltar, where the water of the Mediterranean Sea flows under the less saline water of the Atlantic Ocean. At the interface between the layers shear is responsible for instabilities (Kelvin-Helmholtz), which results in turbulent mixing and entrainment. Gaining deeper understanding of these processes is the main motivation for this thesis. An experimental study into the development of a mixing layer of a twolayer stratified exchange flow is performed and an LIF measurement system was used to obtain the concentration fields. The main objectives of this study were to calibrate and understand the experimental set-up and to investigate the influence of four different parameters on the development of the mixing layer. The calibration of the experimental set-up has led to a simple calibration procedure, which was applied with success. To study the development of the mixing layer the influence of four different parameters was analyzed namely: the buoyant acceleration, the bottom friction, the water depth and the sill slope. After careful analysis of the experimental results it was observed that fluid from the upper layer was entrained into the lower layer in all the experiments. Analysis of the dye visualization showed that the large-scale structures, the Kelvin-Helmholtz instabilities, are mainly responsible for the mixing and entrainment. The overall conclusion was that the variation of geometric condition on the development of the mixing layer has a much stronger influence than the variation of the hydraulic conditions. An enhanced bottom friction affected the Kelvin-Helmholtz instabilities but the mechanism is not completely understood by the author.

Gedurende het ontwerpproces van bodembescherming nabij kademuren krijgt de constructeur te maken met diverse onzekerheden. Hij moet zowel rekening houden met toekomstige schaalvergroting van de scheepvaart, ontwerpformules die maar in beperkte mate aan de praktijk zijn getoetst en veiligheidseisen die aan een de kademuur worden gesteld. Belangrijk is dat de constructeur inzicht heeft in de te kiezen invoervariabelen van de ontwerpformules, zodat een weloverwogen ontwerp gemaakt kan worden. Om dit benodigde inzicht te vergroten worden de ontwerpformules en belangrijker de keuze van de invoervariabelen vergeleken met een probabilistische ontwerpmethode voor een bodembescherming van een referentie kademuur. Door diverse bodembeschermingen nabij kademuren te toetsen aan de deterministische ontwerpformules werd een bodembescherming gevonden die niet meer aan de huidige eisen van de ontwerpformules voldoet. Een studie naar de lodingen wees uit dat de bestorting van deze referentiekade niet in een stabiele toestand verkeerde gedurende de periodieke belasting door de scheepvaart. Het vergelijken van de referentie kade met de probabilistische benadering verliep niet geheel soepel. Een eerste probabilistische benadering wees uit dat veel correlatie bestaat tussen een aantal invoervariabelen. Dit wil zeggen dat een groter type schip ook een grotere schroef heeft en hierdoor een grotere schroefstraal belasting kan veroorzaken. Diverse relaties tussen de invoervariabelen zijn opgesteld wat resulteerde in een tweede benadering. Volgens deze benadering is er een grote verschilfactor tussen âbegin van bewegenâ en het daadwerkelijke âtransportâ van stenen. Dit wil zeggen dat een bepaald type schip de stenen wel kan laten bewegen maar nog niet voor een grote ontgrondingskuil kan zorgen. Hierdoor bestaat de mogelijkheid te ontwerpen met een mobiliteitscoëfficiënt, zodat bodembescherming zo kan worden ontworpen dat een bepaalde toestand ongewenst is en enige beweging van stenen acceptabel is. Wanneer een bodembescherming nabij een kademuur ontworpen wordt, is een integrale aanpak gewenst. De ongewenste gebeurtenissen ten gevolge van een ontgrondingskuil naast een kademuur kunnen ervoor zorgen dat de kademuur bezwijkt of tijdelijk niet beschikbaar is. Deze gebeurtenissen kunnen enerzijds leiden tot grote herstelkosten aan de bodembescherming en de kademuur. Anderzijds worden er grote economische verliezen verwacht voor de terminal. Een eerste benadering van de ongewenste gebeurtenissen en de gevolgen hiervan heeft uitgewezen dat de bodembescherming ontworpen moet worden voor een geringe kans op de toestand âbegin van bewegingâ. Dit kan vertaald worden naar: âfrequente ontgrondingskuilen naast de kademuur zijn ongewenstâ. Wellicht kan het toepassen van het probabilistische model in combinatie met het doelgericht uitvoeren van lodingen leiden tot het oplossen van de onzekerheden in de ontwerpformules en leiden tot optimalisatie van het aantal lodingen. Enerzijds kan wanneer het aantal lodingen geoptimaliseerd wordt, besparing van kosten worden verkregen. Anderzijds kunnen de ongewenste effecten van schaalvergroting worden verminderd. Door de tijdsperiode tussen een loding en het ontstaan van een ontgrondingskuil te verkorten, blijven de veiligheidseisen, gesteld aan de kademuur, gewaarborgd.

Collection of long-term data sets of wave characteristics and bathymetry with high resolution in time is a prerequisite to improve our understanding of nearshore coastal dynamics. Advanced video monitoring systems allow to sample these data automatically, on a long-term basis and without the need to deploy in situ instruments in a hostile environment. Recently, a technique was developed to derive wave frequency-direction spectra from time series of pixel intensities (Holman and Chickadel, 2004). A second technique (Stockdon and Holman, 2000) quantifies nearshore bathymetry from videoderived estimates of wave phase speed. Both techniques were successfully tested against field data collected at Duck (NC) and near San Diego (CA); their applicability for typical North Sea conditions as found along the Dutch coast is unknown yet. The central aim of this work is to apply and assess the applicability of the existing methods to estimate wave characteristics from video imagery with data from the Dutch coast. To achieve this central aim, the Holman and Chickadel (2004) model is used to determine directional wave spectra at Egmond aan Zee (NL) and the accuracy of the results is assessed. Furthermore a new analysis technique is developed to determine wave phase speed and corresponding bathymetry from video using cross correlation analysis, as opposed to the spectral technique developed by Stockdon and Holman (2000). The work described here is part of the ONR funded BeachWizard project (Cohen et al, 2006), which aims at the nowcasting of bathymetrical evolution through assimilation of remote sensing data and model computations of nearshore coastal processes. The analysis of wave direction, period and celerity from time stack images was performed with data collected at Egmond aan Zee along the Dutch coast. The field experiment was carried out from 20 September 2005 to 29 October 2005 in cooperation with the Utrecht University. During this field campaign data were simultaneously collected by video (half hourly time stack images) and in situ wave instruments in the intertidal zone. During the field campaign mostly mild wave conditions occurred and a complex, highly irregular beach morphology was noticed. The final dataset consists of 2.5 days of good quality time stacks at half hourly intervals and concurrent in situ measurements (water level, wave height, period and direction) at three locations, resulting in 43 time-series for ground-truthing. Wave data sampled from an offshore buoy at 21 m water depth are used for ground-truthing the deeper optical instruments (outside the intertidal area).

De Amstelhof is een historisch complex aan de Amstel in Amsterdam. Het verzorgingshuis is gebouwd in 1681 en heeft tot op heden die functie behouden. Door de schaal van het gebouw en de bijzondere functie in de binnenstad is de morfologie van de bebouwing op het bouwblok afwijkend t.o.v. de directe omgeving. Het verzorgingshuis kan niet meer aan de huidige eisen voldoen en het aanpassen is een zeer kostbare ingreep. Bovendien zal de bouwhistorische waarde van het gebouw verloren gaan. Via de stichting Nieuwe Kerk Amsterdam zal een dependance van de Hermitage in St Petersburg worden geopend in Amsterdam. De Amstelhof vormt de huisvesting van dit nieuwe museum. Met LaGroup (adviesbureau) en Hans van Heeswijk Architecten is een Programma van Eisen samengesteld waaraan het ontwerp moet voldoen. In totaal een programma van ongeveer 15000m2. Het ontwerp bestaat uit een nieuwe oostvleugel (de huidige oostvleugel dateert uit de jaren '70) die de hoofdvorm behoudt van de bestaande situatie. In deze vleugel worden de ontvangstfuncties van het museum gehuisvest. In de noord- en zuidvleugel bevinden zich de grote tentoonstellingszalen. De meest historische westvleugel blijft behouden en krijgt de grandeur terug die het ooit had. Het ontwerp maakt gebruik van twee in elkaar verweven looproutes die strategisch met elkaar zijn verbonden. Op die manier zijn tijdelijke exposities mogelijk. De museumzalen maken voor het (dag)licht gebruik van de orientatie in het gebouw. De architectuur van de nieuwe toevoegingen maakt gebruik van de bestaande materialisering, maar dan toegepast in een strakke en sobere vorm.

Wave surfing is existing and becoming more attractive in the Netherlands. However natural wave conditions are not suited to encourage the sport. To improve the surf conditions of the local waves, Artificial Surf Reefs are potential solutions. As a part of intentions to optimise the design of Artificial Surf Reefs, this thesis is aimed at gaining insight into the wave-induced circulations and the wave-current interactions around an artificial reef. Impacts of the channel width on these processes were assessed by varying the width of the channel. Several surf-ability parameters were measured or observed to verify the performance of the proposed design. The surface currents on either side of the reef show a decrease in intensities and dimensions resulting in less intense wave-current interactions around the structure. It was found that rip currents with a Froude number smaller than 0.1 do not cause negative impact on the breaker shapes.