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When designing a new port it is important to predict the operation efficiency of the port. In this respect, it is desirable to predict the possible downtime of a new port in an early phase of the design process. Downtime depends strongly on the moored ship motions. In the past decades several numerical models were developed to predict the behaviour of moored ships in waves. They are referred to as Six Degree of Freedom (SDF) models. These models, such as TERMSIM and BAS, are complex and require quite detailed input data. This detailed information is not available in the planning phase of a new port. Consequently, it is desirable to estimate possible downtime by means of a simple model that estimates the ship's behaviour without detailed input data. With this in mind Delft University of Technology started a research programme that consists of a number ofMSc- projects possibly leading to a PhD-project. The research objective of the programme is to investigate the possibilities of simplification of the models used nowadays. In this respect the aim is to find straightforward relationships to describe the behaviour of moored ships subjected to incident waves. It is emphasized that this simplified model is not meant to replace the Six Degree of Freedom models. The simple model is a valuable design tool, to be used in an early stage of the port development process. This report covers one of the MSc-projects defined as "The analysis of model measurements concerning the behaviour ofmoored ships in long wave ". It concerns the model tests of the planned "Coega Harbour" in South Africa. Part of this project is carried out in South Africa, at CSIR (Council for Scientific and Industrial Research), where data of the model tests are available. The aim of the project is to gain insight in the importance of the various parameters and their mutual relations. An important issue is the validation of relationships mentioned in the literature. The main objective is to derive straightforward relations between motions of a moored ship and the wave field near the ship. Hypotheses with regard to the surge, sway and roll motion are derived from the theory of a moored ship. These hypotheses are verified using the data measured in the physical model. This data is limited to one type of ship moored with one type of mooring system inside one specific harbour. Consequently, the conclusions do not contain general validity. Nonetheless, the results present tools that contribute to the understanding of the response of a moored ship to incident waves.

This thesis investigates the stability of rocks in toe bunds for rubble mound breakwaters. Presently recommended design tools lack a reasonable degree of accuracy to assess required toe element dimensions. The goal of this research is to improve the insight in the physical process related to stability of toe bund elements under wave load. Analysis of presently recommended methods led to the following conclusions: a. The formula of Van der Meer is no improvement of the formula of Gerding. b. Both methods use an inappropriate relation between stability and damage. c. The method of Van der Meer may often underestimate the required toe rock size. A new hypothesis is formulated to describe toe rock stability. The concept for the model of this study is based on two steps: Step 1: Assessment of the local water motions at the toe bund. The amplitude of local velocity is calculated by summation of the contributions of the incoming wave and down rush, taking a phase difference into account. Step 2: Description of the critical load on a toe rock. The Rance/Warren stability criterion is used with a theoretical adaptation that accounts for porous outflow. Coupling these two steps implies that a rock will move if the occurring velocity exceeds the critical velocity. An evaluation of the hypothesis is performed and the model is fitted to available test data. The accuracy of stability assessment is increased with respect to previous methods. The model of this study has more resemblance to the test data and can be used to predict the required toe rock size in design. This is verified for the applicability range of the data set of Gerding.

The Port of Thessaloniki is the second biggest port in Greece after Piraeus. Located in the Northern part of the country, it has a large hinterland above it, the Balkan Peninsula, which renders the Port a transit one. It is naturally protected from winds and waves and it is the best alternative for vessels coming from the Suez Canal and heading towards the Balkans. Competition though is intense in the Adriatic and the Black Sea especially due to the container industry booming as well as the concession of several container terminals in the region to international stevedoring companies. The Port of Thessaloniki seems to be at the moment the leading spoke port in the region. In order thus to maintain this leading position, a proper Masterplan is required, something that has been missing for the last years. This Thesis is the result of an effort to create such a port planning. An inventory of the present situation of the Port was conducted taking into account elements like dry and wet infrastructure, road and rail networks, connections with the regional and national transport networks as well as waterside and landside handling equipment using methods like the queuing theory. These figures were compared to the present cargo and passenger throughput in order to depict deficiencies, lacks and surpluses per terminal. The future needs were then demonstrated based on forecasts. These forecasts were the combination of the extrapolation of past data, the consideration of several transport trends (containerization, liquefied natural gas) as well as the insight in the financial situation of the Balkan countries that constitute the potential customers of the Port. Three different growth scenarios were assumed while the 28-years duration of the Masterplan was divided into three periods (2008-2015-2025-2035). Having these needs as a base, eight alternatives were generated. A multi criteria analysis was then used in order to end up with the three most promising alternatives; the validity of this analysis was verified by five sensitivity checks which demonstrated similar results. Finally an ideal port layout was chosen which was accompanied by the respective construction phasing. The present Thesis was meant to fill a gap; that of the lack of a Masterplan. Fortunately, it can be concluded that the present condition of the Port is adequate for the current cargo and passenger throughput which shows that the rough planning that has been implemented by the consequent authorities until now was successful. Moreover, from now and on, a Masterplan should be considered as mandatory and the present Thesis comprises the ideal blueprint for this. In order to render this report more realistic though, regular updates shall be conducted almost every five years while the forecasts shall be checked and readjusted continuously.

Wave height distributions on shallow foreshores deviate from those in deep water due to the effects of the restricted depth-to-height ratio and of wave breaking. Laboratory data of wave heights on shallow foreshores of different slopes have been analysed to determine these effects and to derive generalised empirical parameterisation. A model distribution is proposed consisting of a Rayleigh distribution or a Weibull distribution with exponent equal to 2, for the lower heights and a Weibull with a higher exponent for the higher wave heights. The parameters of this distribution have been estimated form the data and expressed in terms of local wave energy, depth and bottom slope, yielding a predictive model that is to be significantly more accurate that existing expressions.

Computer models are commonly used to simulate the behaviour of the coast in response to natural processes (e.g. storms, extreme sea levels) or management plans (e.g. beach nourishment, channel dredging). The COAST3D project was initiated to improve and validate these numerical models. COAST3D stands for Coastal Study of ThreeDimensional Sand Transport Processes and Morphodynamics. In March 1999, a COAST3D Pilot experiment was held in Teignmouth on the coast of Devon in Southwest England.Teignmouth has a very irregular coastline. It comprises a tidal inlet adjacent to the beach and a sandstone cliff, making it three-dimensional.This study involves the modelling of the Teignmouth site with data from the Pilot campaign. The general goal is to validate Delft3D-MOR against the field data taken in Teignmouth. For this purpose, a model grid covering the Teignmouth site is constructed. The hydrodynamic boundary conditions are determined by nesting the Teignmouth grid into a larger model, the Lyme Bay Model, which is in turn nested into the Continental Shelf Model. After the nesting procedure, the boundary conditions are calibrated with the use of water levels recorded during the Pilot campaign. The influence of the Teignmouth estuary is calibrated by varying the bed roughness inside the estuary. However, the tidal flow through the estuary mouth can not be modelled accurately, as the bathymetry data used in the Teignmouth model is outdated. The different COAST3D modelling teams agreed to carry out three common test cases: 1) A spring tidal cycle without waves. 2) A hypothetical situation with high waves and a fixed water level. 3) A neap tidal cycle with large waves. The focus of this study is also on these three test cases.The suspended and bedload transports and resulting bed-level changes are also computed for each test case. This is done with and without intratidal bed updating.

Om problemen betreffende ruimtetekort in de Rotterdamse haven het hoofd te bieden wordt onderzocht of een nieuw haventerrein voor de kust kan worden aangelegd, de TweedeMaasvlakte. Dit terrein moet voldoende worden beschermd tegen golven afkomstig uit zee en hoge waterstanden. Om golfbrekers en andere civieltechnische constructies ten behoeve van dit project te ontwerpen en uit te voeren is een goede beschrijving van het hydraulische klimaat in de uiterste grenstoestanden in de bruikbaarheidsgrenstoestand vereist. Het afstudeerrapport heeft betrekking op de beschrijving van het hydraulisch klimaat in de uiterste grenstoestand. Dit klimaat zou kunnen worden vastgelegd door een gezamenlijke kansdichtheidsfunctie van de hydraulische lange termijn variabelen. Deze hydraulische variabelen zijn tenminste: de waterstand, de significante golfhoogte, de piekperiode en de hoofdgolfrichting. De vraag is, hoe deze gezamenlijke kansdichtheidsfunctie moet worden beschreven. Dit kan geschieden door middel van fysische modellen of door modellen gebaseerd op de meetdata. De beoogde locatie van de Tweede Maasvlakte ligt ter plaatse van relatief ondiep water terwijl er slechts metingen beschikbaar zijn op relatief diep water (Euro-O platform). De beoogde werkwijze is het hydraulische klimaat eerst ter plaatse van de relatief diep waterlocatie te beschrijven met behulp van fysische modellen en later te vertalen naar de relatief ondiep waterlocatie. Deze vertaalslag valt buiten de hoofdlijn van dit afstudeeronderzoek. Het verband tussen de waterstand en de significante golfhoogte kan worden beschreven door de methode van Vrijling en Bruinsma, welke gebruik maakt van een gemeenschappelijke ontstaansbron, het windveld. Het verband tussen de significante golfhoogte en de piekperiode kan worden beschreven door het golfsteilheidsmodel voorgesteld door Vrijling. Hierbij wordt de koppeling gelegd via de diep water golfsteilheid. Tenslotte kan de hoofdgolfrichting worden gekoppeld aan de windrichting binnen een storm. Om de modellen te verifieren en te kalibreren is er een dataset geselecteerd met onderling onafhankelijke stormen door een combinatie van de Peak Over Threshold methode en de methode van depressiebaan selectie. Bij verificatie van de geinplementeerde modellen geeft de golfgroeirelatie van Bretschneider, welke onderdeel is van het model van Vrijling en Bruinsma, voor golven op ondiep water en beperkte strijklengte te lage waarden voor de significante golfhoogte. Een ander onderdeel van de methode van Vrijling en Bruinsma is de windopzet-windsnelheidsrelatie, waarvan het gemiddelde goed te bepalen is. De metingen vertonen echter wel behoorlijke spreiding om dit gemiddelde. Kennis van de meteorologische weerssituatie boven de gehele Noordzee lijkt belangrijk te zijn om dit laatste aspect te kunnen verklaren. Indien deze twee problemen worden verholpen, kunnen de geimplementeerde modellen het hydraulische klimaat waarschijnlijk goed beschrijven. Extrapolatie kan in dat geval ondersteund worden door fysica. Er is bekeken in hoeverre het geimplementeerde golfsteilheidsmodel wordt ondersteund door het modelvan Battjes/ Mitsuyasu gebaseerd op de piekfrequentie van het zeegangsspectrum. Ook het op metingen gebaseerde model van De Haan is met dit geimplementeerde golfsteilheidsmodel vergeleken. Tenslotte is het geimplementeerde model van Vrijling en Bruinsma vergeleken met deze methode DeHaan. Het fysisch-theoretisch model van Battjes/ Mitsuyasu lijkt het golfsteilheidsmodel niet tegen te spreken en ook de methode De Haan geeft redelijk overeenkomende resultaten, ondanks de verschillende aannames. Bij vergelijking van de modellen voor de relatie tussen waterstand en significante golfhoogte treden er niet te verwaarlozen verschillen op tussen de methode De Haan en de methode van Vrijling en Bruinsma.

Floods are a threat to millions of people who are living in lowlands. A lot of research is done about flood risk analysis. A general expression of flood risk is the probability of flooding times the consequences. This graduation research focuses on the probabilities of failure and leaves the consequences out of the comparison. The objective is to find the most interesting parts for a flexible and widely applicable reliability method. By describing existing reliability methods and applying those to a model dike and a dike ring in the German Bight area (Germany) more insight will be gained into the advantages and disadvantages of these methods. The reliability methods PC-Ring and ProDeich are described and compared with each other. PC-Ring is developed in the Netherlands and used in the VNK-project to test the Dutch dike rings. ProDeich is developed in Germany as a model to assess the overall failure probabilities for sea dikes. Both methods are designed to analyse the separate flood defences and systems of flood defences. Furthermore the approach of determining the failure probability is in general the same. The dike ring is divided in equal sections. A limit state function describes the strength and loading for the failure mechanisms and the failure probabilities are calculated using probabilistic level II or level III calculations. Differences can be found in the general background of the methods, the application area, the available fault trees and failure mechanisms. The use of stochastic and hydraulic input is rather different in PC-Ring and ProDeich. PC-Ring considers correlations and dependencies, while this is neglected in ProDeich. The amount of hydraulic input in PC-Ring is very extensive compared to ProDeich. Differences in the output are caused by the following aspects: The calculation methods lead to differences for all failure mechanisms. Piping is in PC-Ring preceded by heave. Differences in the limit state functions. Different use of model factors (which account for uncertainties in the used models). Different wave heights and periods, these are provided in a different way in each program and therefore lead to different results. The comparison of both methods leads to many differences and similarities and a new software tool should comprise aspects from both programs.

In the year 1991 the Technical Advisory Commission (TAW-A4) ordered a full scale investigation on wave impacts on an asphaltic concrete revetment. The goal of the experiment was to gain insight into the mechanisms which would lead to failure, cracking of the revetment. Also the behaviour of the revetment after failure (residual strength) was studied. To gain insight in the behaviour of the revetment, strain measuring devices and pressure transducers were placed into the revetment. The measured strains were compared with calculated strains by several researchers. One of the researchers concluded there was almost no resemblance between the measured and calculated strain and recommended to perform a sensitivity analysis on the calculations. This conclusion and recommendation is what resulted into the subject of the thesis. Due to extensive testing of materials in the last fifteen years a better understanding of material behaviour is achieved. This concerns in particular the modulus of elasticity of asphaltic concrete and the modulus of subgrade reaction. This knowledge is used in the thesis to get new results, by recalculation, from the same model. To perform a sensitivity analysis a stochastic simulation is used. A choice is made for using the Monte Carlo method for simulation of the strains and the results of the simulations are compared with the measured strains. The conclusions are divided into conclusions regarding the recalculation and conclusions regarding the Monte Carlo simulation. In the recalculation a better agreement between the measured and calculated strain is obtained. The model describes the calculated dynamic strain in a good way. This is also concluded by Ruygrok, one of the researchers who also investigated this Delta flume experiment. The simulated strains calculated with the Monte Carlo method are not in agreement with the measured strains. The difference between the calculation and the measurements are assigned to the differences between the quasi-static and the dynamic strain. Another reason for the differences is that the information of the wave impacts stored in the impact factor distribution cannot be divided into time and space, which leads to a too rough approach in the simulation.It is recommended to investigate the relation between the quasi-static or dynamic strain with the total strain. If the quasi-static strain adds extra damage to the revetment this part should be taken into account when a safety assessment is performed.

Na analyse van de resultaten van de modelproeven zijn de volgende criteria voor Tetrapoden in een enkele toplaag bepaald: Bezwijken Ns=1,2; Start van Schade Ns=1,2 Geen Schade Ns=0.8. Ns is hierbij het schadegetal (golfhoogte gedeeld door relatieve dichtheid en blokdiameter) Na vergelijking van deze criteria met de ontwerpformule voor Tetrapoden in een dubbele toplaag bleek dat, bij de in de modelproeven gebruikte plaatsingsmethode en plaatsingsdichtheid, de elementen in een enkele toplaag, bij 'geen schade', 6,6 keer zwaarder moeten worden uitgevoerd. Per vierkante meter kan dan bijna met de helft van het aantal elementen worden voldaan. Ondanks de grotere en zwaardere elementen kan er toch een betonbesparing van ongeveer 28% gerealiseerd worden. In een enkele toplaag kan echter minder kernmateriaal worden gebruikt om de kruinhoogte en -breedte gelijk te houden aan een toepassing met een dubbele toplaag. Tetrapoden in een enkele toplaag lijken voordeliger dan in een dubbele toplaag (minder elementen en een kleiner betonverbruik per vierkante meter). De elementen moeten, bij een porositeit van ongeveer 62%,6,6 keer zwaarder zijn dan bij toepassing in een dubbele toplaag. De kans dat deze grotere elementen breken is waarschijnlijk niet gering. Daarnaast is het nog de vraag of zwaardere elementen wel aanvaardbaar zijn met het oog op het te gebruiken materieel. Verder kan men zich afvragen of het gebruik van kubussen in een enkele toplaag geen betere optie is. Tijdens het modelonderzoek zijn Tetrapoden in een enkele toplaag zeer regelmatig en open geplaatst. Bij gebruik van een dichtere plaatsing, waarbij per vierkante meter meer elementen worden gebruikt, kan wellicht een hogere stabiliteit worden bereikt door een verhoogde haakweerstand. Een daarmee verkregen hogere stabiliteit, waardoor de elementen lichter dan op dit moment het geval is, kunnen worden uitgevoerd, kan Tetrapoden in een enkele toplaag aantrekkelijker maken.

Door de eeuwen heen heeft Nederland een grote verbondenheid met het omringende water gehad. De ligging aan zee en de verbindingen met het achterland via de grote rivieren zijn bepalend geweest voor onze welvaart. Deze ligging heeft echter ook gezorgd voor een voortdurende strijd die geleverd moet worden om het land tegen overstromingen te beschermen. Deze overstromingen hebben vaak grote schade tot gevolg. Om het achterland te beschermen zijn in het verleden vergaande maatregelen getroffen zoals bijvoorbeeld de Deltawerken. Deze enorme constructies zijn gebouwd na de watersnoodrampvan 1953. Om de kustlijn op zijn plaats te houden worden tegenwoordig in Nederland veelal zandsuppleties uitgevoerd. De laatste jaren worden echter steeds meer altematieven onderzocht. Een van die alternatieven bestaat uit de aanleg van offshore golfbrekers. Offshore golfbrekers zijn harde constructies die op een bepaalde afstand voor de kust geplaatst worden. Ze hebben tot doel de achterliggende kust te beschermen. Door het Civieltechnisch Centrum Uitvoering Research en Regelgeving (CUR) is een studie uitgevoerd naar de toepasbaarheid van offshore golfbrekers parallel aan de kust. Offshore golfbrekers beinvloeden door hun vorm en locatie plaatselijk de hoogte en richting van invallende golven. Dit leidt tot lagere golven in het gebied tussen de golfbrekers en de kustlijn. Als gevolg neemt het zandtransport langs de kust af en kan er sedimentatie optreden. Nadeel van het gebruik van offshore golfbrekersis het optreden van lijzijde erosie. Aanleg van een offshore golfbrekersysteem zal het verlies van zand (erosie) niet geheel kunnen stoppen. Aanvullende zandsuppleties zijn vereist om de positie van de kustlijn te behouden. Om de grootte van deze aanvullende zandsuppleties te kunnen bepalen is een aangepast software model gebruikt, namelijk het multi-layer model. Met het multi-layer model zijn een aantal verschillende offshore golfbrekersystemen berekend. Tevens is een ontwerp ondersteunend model ontwikkeld, dat aan de hand van invoerparameters de kosten van een offshore golfbrekersysteem berekent. Binnen deze afstudeerstudie is onderzocht wat de mogelijkheden van de beide modellen zijn en welke aanpassingen gedaan kunnen worden om deze modellen te verbeteren. Aan de hand van de resultaten is het ontwerp ondersteunend model aangepast. Verder is onderzoek gedaan naar de invloed van een andere golfrichting op de werking van offshore golfbrekers. In het oorspronkelijk ontwerp ondersteunend model kan slechts een evaluatie van acht verschillende golfbrekersystemen worden uitgevoerd. In deze studie is het model zo aangepast dat door interpolatie een schatting gegeven wordt van de effectiviteit van de tussenliggende waarden. Het model is hierdoor voor meer golfbrekersystemen te gebruiken. Verder kan in het oorspronkelijke ontwerp ondersteunend model slechts een situatie tegelijkertijd worden uitgerekend. Om voor verschillende situaties tegelijkertijd de bijbehorende offshore golfbrekerkosten te kunnen bepalen is een menu aan het model toegevoegd, namelijk een optimalisatie menu. Het is hierdoor eenvoudiger een optimale parameterwaarde te vinden. Tevens kan de invloed van parameters op meerdere golfbrekersystemen tegelijkertijd bepaald worden. Met behulp van dit menu zijn voor verschillende parameters berekeningen uitgevoerd.In het CUR onderzoek zijn slechts voor een golfklimaat berekeningen uitgevoerd. Om inzicht te verkrijgen in de invloed van een andere golfinvalshoek op de werking van offshore golfbrekers is een literatuurstudie uitgevoerd. Uit de studie is gebleken dat een grotere invalshoek van de golven een positieve invloed heeft op de effectiviteit van een offshore golfbrekersysteem. De sedimentatie in het beschermde gebied neemt toe. Een negatieve invloed is de toename van lijzijde erosie.

After Hurricane Katrina the Bring New Orleans Back committee advised to use the Gentilly Ridge to split the Orleans Metro Bowl into compartments in order to reduce the consequences of a flood. The Gentilly Ridge is a natural sand elevation (ridge) of approximately 0,50 1,00 meter NAVD88 in the OMB landscape. The objective of this thesis is to determine the cost-effectiveness (risk reduction versus construction costs) of compartmentation of the Orleans Metro Bowl (OMB) in comparison with an improvement of the primary levee system. Three alternative compartment levees are compared with one primary system improvement. In this thesis the total flood risk of the OMB has been represented in two scenarios: the Katrina event (hurricane class III) and a hurricane class IV event. - The Katrina event is the complete scenario of the Katrina disaster of August 29, 2005. The probability of the event is set to be 1/50 per year. - A hurricane category IV event. The probability of the event is set to be 1/200 per year. Once the probability (in probability/year) and the consequences (in $) of a scenario and alternative have been determined the risk (in $/year) is known. This risk is calculated to a Net Present Value ($) to compare with the costs of a alternative ($). With a detailed cross-section of the compartment levees a calculation of the heightening costs of an earthen levee for each compartment trace has been made. Compartment levee 3 appeared to be less cost-effective than the levee improvement and drop-out. An boundary optimal design level for compartment levee 1 and 2 is calculated and appeared to be both 1,50 meter NAVD88. To overcome a disaster like Katrina, a compartment levee alone will not suffice, therefore the cost effectiveness of a combination Levee improvement and compartment levee is elaborated. Compartment levee 1 (1,50 meter NAVD88) is a quick and cost effective way to deduct the total risk for economical damage in the OMB for the short term. Once the total primary system has been improved, a compartment levee (trace 1) is still of economical value.

Surfing as a sport is growing. Locations with good surfing conditions are limited and therefore crowded. The growing interest for the sport led to a new concept, surf pools. Surf pools mimic good surfing conditions found along the coast. This thesis is about the technical feasibility of a new surf pool concept, creating surfing waves in a circular pool by towing ship-like hulls around. The hulls are towed along the outer wall of the pool and waves generated by these hulls propagate inwards and break on an island in the middle of the pool. The waves break around the island which theoretically leads to endless surf rides. The initial design as suggested by Webber is based on a pool diameter of 200 m and a water depth of 3 m. The objective of his design to generate 2 m high waves for intermediate to expert surfers. Because of the lack of knowledge about ship induced waves in such an enclosed environment, a physical and a numerical model study are carried out. Various hull sizes are towed in a towing tank and the surface elevations are measured and analyzed. From this physical model study it was concluded that the wave pattern behind a hull is the result of a complex interference pattern and is easily disturbed when the velocity beside the hull becomes large. The difficulties of wave generation by a hull therefore lie in the return currents. The magnitude of the return flow is a function of the blockage, the percentage of the cross section of the pool blocked by the hull. In case the blocking and the velocity are too large, water accumulates in front of the hull and the wave field behind the hull is disturbed, the so-called trans-critical regime. Maximum wave height is found when to towing a hull at the onset of this trans-critical regime. The initial wave pool design is evaluated, and it was concluded that the water depth of 3 m is insufficient to generate the desired 2 m waves. Therefore an amended design is presented. Water depth is increased to 7 m and the generation area is enlarged to reduce the blockage to 5%. The large generation area causes a weak return flow and therefore less turbulence in the pool. In such a cross section it is considered technically possible to generate 2 m high surfable waves.

For several years the Department of Physical Geography ofthe University of Utrecht has conducted surveys on the river Allier in France. These surveys always took place during periods of low discharge because at high or even moderate discharges measurements are impossible. As information on the flow during a flood is important to understand the river morphology, a flow model of a part of the Allier was made to simulate the flow during a flood. During a survey in the summer of 1998 bathymetric data and flow measurements were collected. With this data a flow model was made and calibrated. The discharge during the survey was approximately 20 m3Is. During the calibration it became clear that the downstream boundary condition (a water level) could not be generated well. This problem was overcome by moving the boundary to a flow measurement section where the water level for a discharge of20 m3/s was known. However this left a problem for simulation at higher discharges than 20 m3/s. The influence ofan error in the downstream boundary condition was estimated both numerically as well as with the Bresse approximation. Both methods showed the backwater effect introduced by an error to extent for about 1000 m upstream of the boundary. The magnitude of a water level error however, was shown to decrease rapidly in the upstream direction. To simulate flow during a flood several simulations were made, steady- (with a constant discharge) and unsteady state (with a varying discharge). Ten steady state simulations were made, increasing in discharge from 100 to 1000 m3/s. In the unsteady state run the flood of November 1994 was simulated. The simulations showed the flow mainly to follow the main channel, leading to an inbank flow pattern. The position of the secondary flow cells - where the bend radius of curvature is smallest - also indicated an inbank flow pattern. Velocities up to 4 m/s were found in the main channel leading to very large bed shear stresses. At several places the flow was directed onto the point bars. The bed shear stress magnitude here indicated that large grain sizes could be transported onto the point bars. The differences between the steady state and the unsteady state simulations were small. Although there were some differences the flow pattern and the magnitude ofthe velocity were the same. This means that for a global impression ofthe flow pattern at a certain discharge, a steady state simulation is sufficient. This saves a lot of computation time as the unsteady state simulation has a much larger computation time. Armour layers are layers 0 f coarse grains on top of the bed. They were found at several places in the survey area. During the survey a number of the armour layers were sampled. With the aid of the Oak Creek model by Parker (1990) the threshold of motion ofthe grain sizes within these armour layers was estimated. By combining the Oak Creek model and the bed shear stresses from the flow model it was shown that the threshold of motion was exceeded for all grain sizes within the sampled armour layers. Also a rough indication of the surface grain size distribution was given based on the Oak Creek model and the bed shear stresses derived from the flow model. However, the applicability of Oak Creek model to the river Allier was not tested. This requires sediment transport measurements. For the various coefficients in the Oak Creek model the literature values were used.

De afgelopen tien jaar is gebleken dat de rivieren in Nederland, en met name de Rijn, een afvoerregime vertonen dat verandert, en dat er regelmatig extreem lage en hoge afvoeren zijn. De meest recente extreem lage waterstanden werden geregistreerd in 2003. In 1993 en 1995 werd Nederland geconfronteerd met overstromingen wegens extreem hoge waterstanden. De oorzaak van de extreem hoge en lage waterstanden wordt gelegd bij klimaatverandering. Voor de binnenvaart leiden extreem lage waterstanden tot afname van het inzetbare laadvermogen en extreem hoge waterstanden leiden tot vaarbeperking en eventueel tot een vaarverbod. Met het vooruitzicht op meer extreem lage en hoge waterstanden en de voorspelde toename van het goederenvervoer, kan de prestatie van de binnenvaart onder druk komen te staan.

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.

De laatste jaren is er steeds meer aandacht voor natuurvriendelijke oevers. Op veel plaatsen vormen ze een goed alternatief voor traditionele oeverbeschermingen. Verschillende onderzoeken zijn uitgevoerd om na te gaan in welke situaties ze kunnen worden toegepast en op welke manieren ze bescherming bieden. Daaruit is gebleken dat de vegetatie ervoor zorgt dat de stroomsnelheden in de buurt van de oever worden gereduceerd. Daardoor wordt de erosie minder of neemt de sedimentatie toe. In dit proces spelen de wortels van de planten of bomen een bijzondere roI. Want hoewel de bomen bij elkaar de belasting reduceren, worden de individuele bomen op de voorste rij blootgesteld aan de oorspronkelijke belasting. De wortels zorgen ervoor dat de ontgrondingen rondom de stam beperkt blijven. Het is echter niet bekend op welke manier ze dat doen en welke eigenschappen daarvoor belangrijk zijn. Daarvoor is het onderzoek in dit rapport uitgevoerd. Ten eerste is de macrostabiliteit van steile zandoevers onderzocht. Aan de hand van waarnemingen en trekproeven met wortelmonsters is zo'n oever met een wortellaag geschematiseerd en doorgerekend met het softwarepakket MStab. Ten tweede is de binding tussen wortels en zandkorrels onderzocht. Daarvoor zijn een aantal monsters genomen en bekeken met een binoculaire microscoop. Ten derde is experimenteel onderzoek gedaan naar de mechanische aspecten van wortels die effect hebben op de erosie van de bodem. Dat is een vervolg van eerder onderzoek. De wortels zijn nagebootst door een mat met een driedimensionale structuur van draadjes. Deze is aangebracht in een zandbodem en beproefd in een stroomgoot. Met een peilnaald zijn de langsprofielen opgenomen als functie van de tijd en van de gemiddelde stroomsnelheid. Verder is een aantal eigenschappen van de mat gevarieerd. Uit het onderzoek naar de macrostabiliteit van steile zandoevers bleek dat wortels deze aanzienlijk kunnen verbeteren. Ze doorsnijden het afschuifvlak van de oever, waardoor het weerstandbiedende moment groter kan worden. Uit het onderzoek naar de binding tussen wortels en zandkorrels bleek, dat grote korrels, in tegenstelling tot kleine korrels, niet of nauwelijks worden gebonden aan de wortels. Toch heeft eerder onderzoek aangetoond dat wortels de ontgronding reduceren in grof zand. Dat betekent dat er andere aspecten moeten zijn die daarvoor verantwoordelijk zijn. Daar is naar gezocht in het experimentele onderzoek in de stroomgoot. Daaruit bleek dat de experimenten met de mat vergelijkbare resultaten opleverde als de experimenten met echte wortels in eerder onderzoek. Daaruit kan worden geconcludeerd dat de eigenschappen van de mat goed overeenkomen met de mechanische eigenschappen van de wortels. Verder bleek dat de wortels niet het begin van beweg/n beinvloeden, maar de afhankelijkheid van de stroomsnelheid. Want binnen het snelheidsinterval van dit onderzoek (0,35 m/s < v < 0,85 m/s) geldt: hoe hoger de stroomsnelheid is, des te groter is het effect van de wortels. Verder lijken wortels ervoor te zorgen dat de evenwichtsdiepte van de ontgrondingskuil fors wordt gereduceerd. De wortels beinvloeden de stroming, zodat de belasting op de korrels wordt verlaagd. Er zijn geen aanwijzingen ze de beweging van de korrels afremmen.

Many pressurized sewer systems do not reach their design capacity discharge due to enlarged resistance in the pipe system. An extensive investigation has brought to light that air pockets in pipe systems are an important cause of high resistance in sewer system pipe lines. Air intake by pumps in sumps is one of the main reasons of air pocket formation in sewer systems. But there is still little known about air entrainment due to plunging jets from circular open channels, and air intake by submersible pumps near plunging jets, especially at the scale of real sewer sumps. The research objective is to achieve knowledge and insight into air entrainment from free overfall water jets from horizontal open channels and air bubble intake with submersible sewer pumps. The main questions are: - How does the air entrain into the reservoir? - Where and how many air bubbles can be expected in a certain configuration without any specific measures? - What is the sphere of influence of the submersible sewer pump? - What is a robust measure to prevent air coming into the sewer pump?

Since the container revolution in the mid-sixties and the scale increase it caused, seaports face changing technological developments and economic circumstances. Terminal operators and port authorities have to deal with an increasing number of uncertainties. Especially in container transport competition plays a major role. Containers have a relative large mobility and container transportation routes are less bounded to modalities, ports and logistic chains. As a consequence the substitutability of ports is considerable. Port selection within the logistic chain is part of the selection of the logistic chain which is the primary choice. The market power of shipping companies has been enhanced to the extent that they have gained control of logistic chains. The capacity of container carriers is still growing and as long as there is enough freight to transport they tend to call at less and less ports. There are huge challenges for container ports and their terminals to remain competitive and to handle the anticipated growth with an increase of their productivity, a reduction of port congestion (e.g. Maasvlakte II) and improvement of their hinterland accessibility (e.g. the Betuweline). The overall objective of this research is to provide port authorities with a tool to support their strategic investment planning in a competitive market. The tool should provide port authorities with information on the impacts of, structural and non-structural, capacity improvement measures on the future demand for container service. The present thesis contributes to this objective by the development of the Port Competition Model, a supporting planning tool. The port can be considered a node in a transport network with competition, which faces a dynamic situation concerning the timing and sizing of capacity expansions of other ports and changes in the transport network. The challenge is to incorporate the aspects of the full dynamics of port competition over the network in the Port Competition Model by simulation of the competitive strategies of other ports and the sensitivity of decisions on port investment for such strategies. To this end the Port Competition Model needs to represent varying market shares over the years in order to reflect strategies of other ports. When port planning is based on varying market shares of competitive ports it can be defined as "dynamic port planning". The focus of this research is the reaction of a particular port on a change in the transportation network. A scenario for such change is the entry of new routes via a competing port. This leads to decreased demands and benefits for the particular port. Potential reactions of the ports on this change include investment in port expansion and improvement of hinterland connections. The expansion of a port's surface area takes a central place in this research. The density of ports in Northwest Europe is the highest in the world. This implies severe competition. Four of the five biggest European ports are situated within the Hamburg - Le Havre range: Rotterdam, Antwerp, Hamburg and Bremen. Within this range the ports compete mainly on transit containers. The Port Competition Model has been developed for these four ports within the Hamburg - Le Havre range.

A major part of the breakwaters constructed in the world are the so-called conventional rouble mound breakwaters, which consist of a core, a filter layer and a heavy armour layer. An alternative to the conventional rouble mound breakwater is a berm breakwater. Berm breakwaters have mainly developed in two directions over the last couple of decades. On the one hand a dynamically stable structure, where reshaping is allowed. And on the other hand a more stable multi layered structure often referred to as Icelandic type berm breakwater. When there is a rock quarry, relatively close to the construction site, which is dedicated to the breakwater project, the Icelandic type has proven to be very attractive economically. The basic reason for that is that unlike the other types the Icelandic type utilizes the quarry 100%. This M.Sc. thesis focuses on the Icelandic type berm breakwater. Before an Icelandic type berm breakwater is constructed the stones are divided into classes depending on their size. The smaller armour stones are then placed rather deep where the influence of the wave attack is less, as well as on the rear end of the structure, while the largest stones are placed where the largest wave attack is expected. The goals of the project are the following: a) Design rules for the transaction of stone classes with depth have not yet evolved and the main goal of this project was to develop a stability criterion for the stones in that area (Primary goal). b) Stones on berm. Since the total amount of the largest stones (Class I) is usually limited, the combination of the amount of large stones on the berm and down the berm is important (Secondary goal). c) Recession. Recession will be measured in each test and thereby a large database on the subject will be made available for further research on the subject (Secondary goal). d) The location of the transition of the original and the reshaped profiles as the berm height changes as well as for different stone setups. This is also closely related to the primary goal of the project (Secondary goal). Numbers of model tests were performed in order to reach those goals.