Pilot Sand Groynes Delfland Coast: Efficiency and practical feasibility of a pulse nourishment

In September and October of the year 2009, three sandgroyne nourishments have been executed at the Delfland Coast near the village of Ter Heijde. The nourishments have been executed to restore the sediment buffer in the upper part of the coastal profile. A sandgroyne is a concentrated amount of sediment (200.000m3) artificially nourished from the beach into the sea, appearing in the formation of peninsulas. It was anticipated that the three sandgroynes would be absorbed into the coastal system by the impact of waves and currents, nourishing the upper shoreface from the shoreline until a depth of about -5m NAP over a coastal stretch of about 2.5km. The construction and evolution of the sandgroynes have been monitored intensively. The following research objectives were proposed: 1) Assess the morphological evolution and practical aspects of the sandgroynes constructed at the Ter Heijde coast and 2) Use the site specific knowledge from the Ter Heijde pilot project to create a future perspective of sandgroyne nourishments as a common applied method to nourish the shoreface. This master thesis describes the process of the monitoring campaign, the results of a morhpological data analysis, the results of an initial model simulation set-up and a practical analysis. The sandgroynes have been absorbed in the coastal system, dominantly between the shoreline and the -5m depth contour. However the spatial scale of longshore sediment redistribution was larger than accounted for, driven by the intense wave climate. It is concluded that the sandgroynes can be an effective method for nourishing the shoreface, under flexible contract requirements that acknowledge the dynamics of the natural system.Hydraulic EngineeringCivil Engineering and Geoscience

Urban Regeneration in a Market Oriented Decision Environment: A Deeper Understanding of the Plan-, Decision making and Development Process in a Market Oriented Approach to Urban Regeneration and its Possible Physical and Socio-demographic implications in Dutch Deprived Neighbourhoods

The Dutch government aims since the 1990s at a more market oriented approach in urban planning with different implications in terms of who benefits and loses from interventions in vulnerable places such as neighbourhoods of empowerment (krachtwijken). This policy shift and way of thinking about urban planning implicated big changes in the policies which affected all organisational levels. The changes led to other composition of actors on the local municipal scale with more market oriented parties involved in urban regeneration. These changes are to be found controversial by many professionals in academic and the practising world. A different mix of parties will influence the outcomes and may lead to other consequences in physical and socio-demographic implications in vlunerable areas such as neighbourhoods of empowerment. The objective in this research is to gain a better understanding of the physical and socio-demographic implications that appear in a more market oriented approach to urban regeneration in neighbourhoods of empowerment. The results from this research are valuable for authors whom try to make statements regarding the implications that appear when urban regeneration interventions take place under a more market oriented approach. They can be used for a better understanding of the implications in relation to project specific processes.Spatial Planning and StrategyUrbanismArchitectur

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Document uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science

Pilot Project Sand Groynes Delfland Coast

In October and November 2009 a pilot project has been executed at the Delfland Coast in the Netherlands, constructing three small sandy headlands called Sand Groynes. Sand Groynes are nourished from the shore in seaward direction and anticipated to redistribute in the alongshore due to the impact of waves and currents to create the sediment buffer in the upper shoreface. The results presented in this paper intend to contribute to the assessment of Sand Groynes as a commonly applied nourishment method to maintain sandy coastlines. The morphological evolution of the Sand Groynes has been monitored by regularly conducting bathymetry surveys, resulting in a series of available bathymetry surveys. It is observed that the Sand Groynes have been redistributed in the alongshore, mainly in northward direction driven by dominant southwesterly wave conditions. Furthermore, data analysis suggests that Sand Groynes have a trapping capacity for alongshore supplied sand originating from upstream located Sand Groynes. A Delft3D numerical model has been set up to verify whether the morphological evolution of Sand Groynes can be properly hindcasted. Although the model has been set up in 2DH mode, hindcast results show good agreement with the morphological evolution of Sand Groynes based on field data. Trends of alongshore redistribution of Sand Groynes are well reproduced. Still the model performance could be improved, for instance by implementation of 3D velocity patterns and by a more accurate schematization of sediment characteristics.Hydraulic EngineeringCivil Engineering and Geoscience

Boeren met water, waterberging in combinatie met landbouw

Het project Boeren met Water is een onderzoeksproject in opdracht van de provincie Noord-Holland, de Noord-Hollandse waterbeheerders en Habiforum. Het is een van de vier projecten van het onderzoeksprogramma Meervoudig Ruimtegebruik met Waterberging in Noord-Holland. Boeren met Water verkent de mogelijkheden om waterberging te combineren met agrarische bedrijfsvoering. Het is een toekomstgerichte studie die invulling geeft aan de wateropgaven die in de nota Waterbeleid voor de 21e eeuw worden geformuleerd. De studie is tot stand gekomen in nauwe samenwerking met een studiegroep van agrarisch ondernemers uit de Zeevang en de Beemster. Samen met de betrokken waterbeheerders hebben zij bijgedragen aan het ontwikkelen van nieuwe kennis ten aanzien van meervoudig ruimtegebruik. Het project is uitgevoerd door het Centrum voor Landbouw en Milieu.KWP-collectio

Quantifying Accuracy and Uncertainty in Data-Driven Flight Trajectory Predictions with Gaussian Process Regression

Several initiatives are developed to shift the current paradigm in Air Traffic Management from the tactical-based approach to more strategic-based coordination of flights. This transformation of the ATM system relies on the improvement of predictive models for the 4D flight trajectories. A variety of performance-based and data-driven approaches are developed for trajectory predictions. The accuracy of the predictions is often deterministic and can be highly impacted by uncertainties that occur in each flight. These uncertainties are commonly related to the lack of detailed information concerning the flight intent, or the inaccuracy of positional and weather-related data. To better understand prediction errors and uncertainties in data-driven predictions, this study proposes a novel two-stage Gaussian Process Regression (GPR) approach. By combining historical flight data and flown trajectory of a given flight, the predictive distributions from the GPR allow us to study both prediction errors and uncertainties. To evaluate the model, we applied the method for flights arriving at the Amsterdam Airport Schiphol. We also evaluate and quantify how flight-plan and meteorological information help to reduce prediction error and uncertainty.Control & SimulationControl & Operation

The Effect Of 3D Audio And Other Audio Techniques On Virtual Reality Experience

Three studies were conducted to examine the effect of audio on people's experience in a virtual world. The first study showed that people could distinguish between mono, stereo, Dolby surround and 3D audio of a wasp. The second study found significant effects for audio techniques on people's self-reported anxiety, presence, and spatial perception. The third study found that adding sound to a visual virtual world had a significant effect on people's experience (including heart rate), while it found no difference in experience between stereo and 3D audio.Intelligent SystemsElectrical Engineering, Mathematics and Computer Scienc

Input reduction for long-term morphodynamic simulations

Input reduction is imperative to long-term (> years) morphodynamic simulations to avoid excessive computation times. Here, we discuss the input-reduction framework for wave-dominated coastal settings introduced by Walstra et al. (2013). The framework comprised 4 steps, viz. (1) the selection of the duration of the original (full) time series of wave forcing, (2) the selection of the representative wave conditions, (3) the sequencing of these conditions, and (4) the time span after which the sequence is repeated. In step (2), the chronology of the original series is retained, while that is no longer the case in steps (3) and (4). The framework was applied to two different sites (Noordwijk, Netherlands and Hasaki, Japan) with multiple nearshore sandbars but contrasting long-term offshore-directed behavior: at Noordwijk the offshore migration is gradual and not coupled to individual storms, while at Hasaki the offshore migration is more episodic, and wave chronology appears to control long-term evolution. The performance of the model with reduced wave climates was referenced to a simulation with the actual (full) wave-forcing series. It was demonstrated that input reduction can dramatically affect long-term predictions, even to such an extent that the main characteristics of the offshore bar cycle are no longer reproduced. This was particularly the case at Hasaki, where all synthetic series that no longer capture the initial chronology (steps 3 and 4) lead to rather unrealistic long-term simulations. At Noordwijk, synthetic series can result in realistic behavior, provided that the time span after which the sequence is repeated is not too large; the reduction of this time span has the same positive effect on the simulation as increasing the number of selected conditions in step 2. It was further demonstrated that, although storms result in the largest morphological change, conditions with low to intermediate wave energy must be retained to obtain realistic long-term sandbar behavior. The input-reduction framework must be applied in an iterative fashion as to obtain a reduced wave climate that simulates long-term sandbar sufficiently accurately within an acceptable computation time. Given its potential huge impact on the actual simulation, we believe it is imperative to consider input reduction as an intrinsic part of model set-up, calibration and validation.Hydraulic EngineeringCivil Engineering and Geoscience

Case study Piçarras Beach: Erosion and nourishment of a headland bay beach

Master project report. Piçarras is one of the touristic beaches of Santa Catarina state in Brazil. Piçarras beach is a headland bay beach. In the bay irregular features like an island, rocky outcrops and shoals are present influencing wave propagation. In the south Piçarras is bounded by Piçarras river. The river mouth has been fixated in 1970, after which erosion started. The part just a few hundred meters north of the river jetty has the most severe erosion. The erosion gradually decreases towards the north, where even some accretion has been measured. When the situation became critical a nourishment was executed in 1999, which has disappeared totally on some places. The decrease in beach width causes a devaluation of the houses and a decrease in tourism which consequently leads to a decrease of employment. It is therefore necessary to investigate the causes and the amount of the erosion and to generate measures to counteract the negative impact of the erosion. Prosul, a Brazilian engineering company, has designed a nourishment of which execution started in July 2008. The main goal of this study is investigate erosion at Piçarras beach and to design a nourishment to counteract the effects of the current erosion. A model has been built to represent the situation at Piçarras beach. With the model the evolution of the nourishment and the evolution of the existing plan of Prosul could be evaluated. The bathymetry has been composed of recent profile measurements and old nautical maps. They have all been related to the reference level of IBGE. To investigate the erosion at Piçarras beach the wave climate has been schematised. The available wave data was given for four direction (NE, E, SE, S) in the form of wave heights and periods. To be able to compare what the results of the incoming wave energy from these four directions were on the erosion and accretion on the beach, a schematisation has been made. A representative average wave per direction has been determined, that supplied the same energy input from that direction as did all the different waves from that direction. Headland bay beaches are historically formed in such a way that the incoming waves and thereby the wave energy, arrive perpendicular at the beach, thus absorbing the incoming wave energy in the most efficient way. This theory formed the basis of this schematisation. The mean tidal variation is 0.6m, at spring tide this is 0.9m. Storm surges lead to a set-up in water level of approximately 1.0m. Currents and wind are not taken into account. The sediment present at the beach has a D50 of 0.285mm. The sand used in the nourishment of 1999 was coarser than the native sand, which had a D50 of 0.260mm. Erosion processes can take the sand either in cross-shore direction or in longshore direction. Without looking at the underlying process, just to get a realistic idea of the erosion and accretion patterns, the amount of eroded sediment has been calculated with shoreline changes and deduced erosion rates [2]. The erosion of the past nine years is calculated to be 395,000 m3. To find out where the sediment is transported to at Piçarras beach a model has been build. First the nearshore wave conditions have been modelled with Delft3D (D3D) for the four wave scenarios. These conditions serve as input for Unibest (UB). This program is applied to model the shoreline changes.Hydraulic EngineeringCivil Engineering and Geoscience

Using the private rented sector as a form of social housing

The paper considers the role of the private rented sector in supplying housing that can be defined as social housing. It will do this by considering policy initiatives in Germany, France, the USA and England that use privately owned housing to meet social needs. The operation of these initiatives will be compared. The allocation and rent conditions attached to dwellings supplied under selected schemes will be exam-ined as will the incentives for landlords to offer housing under these conditions. The functions of the conditions and the time limits attached to them will be compared. It will be shown that such schemes raise questions about the definition and the role of the sector in varying institutional contexts. The paper draws on some of the evidence in the authors’ research report for the English Department of Communities and Local Government: Promoting Investment in Private Rented Housing Supply: International Policy Comparisons (November 2010). See: http://www.communities.gov.uk/publications/housing/investprivaterentedhousingOTB Research Institute for the Built Environmen