255 research outputs found
Beheersen van extreme waterstanden in het IJsselmeer, een nieuw perspectief voor een veilig en klimaatbestendig IJsselmeergebied
No full textIn 2008 kwam de tweede Deltacommissie met het voorstel om het waterpeil van het IJsselmeer in de toekomst met 1,5 m te verhogen. Door de verwachte zeespiegelstijging zal het namelijk steeds moeilijker worden om het overtollige water van het IJsselmeer af te voeren naar zee. Om dit onder vrij verval te kunnen blijven doen is een peilopzet noodzakelijk, met ingrijpende dijkverhogingen tot gevolg. In dit afstudeeronderzoek zijn een aantal alternatieve maatregelen onderzocht, waarmee in een betere beheersing van het IJsselmeerpeil kan worden voorzien. Op deze manier kan grootschalige dijkverhoging wellicht worden voorkomen. Het afstudeeronderzoek spitst zich toe op twee zgn.“Alternatieve Beheersmaatregelen” waarmee, tijdens en voorafgaande aan een hoogwater op het IJsselmeer, het peil kan worden verlaagd. 1. Reduceren van de IJsselafvoer met behulp van een nieuw regelwerk in de Pannerdensche Kop; 2. Vergroten van de uitstroom door tijdens extreem hoog water in het IJsselmeer, het Markermeer (incidenteel) als Noodbuffer in te zetten. Naast deze alternatieve beheersmaatregelen is tevens gekeken naar de optie van bemaling via de Afsluitdijk. Hiervoor is, op basis van het meest extreme klimaatscenario volgens het KNMI, een schatting gemaakt van de maximaal benodigde pompcapaciteit bij verschillende combinaties met beheersmaatregelen. Daarnaast zijn ook globaal de (pomp)kosten berekent om het huidige peil in de toekomst te kunnen handhaven.Hydraulic EngineeringCivil Engineering and Geoscience
Verslag van het voorgevallene tijdens het hooge opperwater op de Nederlandsche rivieren in den winter van 1925 op 1926
No full textNa een lagen stand op 21 December 1925 bereikt te hebben begon de Rijn te Keulen sterk te wassen, welk was met een korte onderbreking 26 en 27 December aanhield tot in den nacht van 1 op 2 Januari, waarbij de hoogste bekende stand bij open rivier van 45.63m +NAP of 9.69m +0 werd bereikt. De Maas vertoonde vóór deze hoogwaterperiode geen lagen stand; in den nacht 19 op 20 December werd te Maastricht 42.62m NAP of 1.07m +M.R. als dalstand geregistreerd; de toen intredende was hield aan tot 1 Januari 1926, waarbij ook op deze rivier de bijzonder hooge stand van 46.92m NAP op 1 Januari 1926 op den middag werd bereikt. De waarnemingen tijdens het jongste hoog opperwater hebben doen zien, dat verschillende rivierwaterkeringen niet overal voldoende overhoogte hadden. De overloop, die daarvan op een aantal plaatsen het gevolg was en andere oorzaken, hebben geleid tot doorbraak van verscheidene dijksgedeelten. Hierbij dient opgemerkt te worden dat de meteorologische omstandigheden bijzonder ongustig waren in den winter. De buitengewone omstandigheden, die de rampspoedige vloeden van December - Januari hebben veroorzaakt, worden in dit verslag uiteengezet.Hoogwaterversla
Effectiveness of Nitrate Policy in Flanders (1990-2003): Modular Modelling and Response Analysis
No full textThe impact of current nitrate policy measures in Flanders is estimated. A modular modelling system has been developed for comparing response and pressure indicators and for decomposing the response impact of policy measures. Compared to 1990, the internalised manure surplus is reduced to zero, whereas the distance to target of the soil surface balance to the water quality standard dropped only with 58%. Source-linked and sink-related measures each account for about the half of the manure surplus reduction. The impact of abatement technologies is minor. The modular approach helps to unravel the discrepancy between pressure and response and to propose policy alternatives.abatement technology, DPSIR scheme, nitrogen pollution reduction, Agricultural and Food Policy, B41, C51, H21, K32,
Reading ground water levels with a smartphone
No full textWater ManagementCivil Engineering and Geoscience
Model predictive control on open water systems
No full textHuman life depends on water daily, especially for drinking and food production. Also, human life needs to be protected against excess of water caused by heavy precipitation and floods. People have formed water management organizations to guarantee these necessities of life for communities. These organizations manage a water system within the community and manipulate the water flows in this system to fulfill the water related requirements. To do so, controllable structures, such as gates and pumps are used. The way these structures are controlled, depending on the requirements of the communities, is part of the research field of control on water systems, often referred to as operational water management. In the research "Model Predictive Control on Open Water Systems", the relatively new control methodology Model Predictive Control is configured for application of water quantity control on open water systems, especially on irrigation canals and large drainage systems. The methodology applies an internal model of the open water system, by which optimal control actions are calculated over a prediction horizon.Civil Engineering and Geoscience
Model Predictive Control applied to the Dutch delta, a probabilistic safety analysis
No full textAs many areas in The Netherlands are located below or slightly above mean sea level, or adjacent to large rivers, a lot of effort is put into ensuring the Dutch keep dry feet. The prevention of flooding is the most important and internationally well-known layer in the Dutch water safety policy. Nowadays this takes place by means of taking physical measures, i.e. making sure flood defences (e.g. dikes, barriers) are of adequate height and strength, or allowing enough space for the river to store water in case of extreme discharges. Though very robust, taking physical measures for flood prevention is generally also very expensive. Another method to prevent flooding, currently hardly applied in The Netherlands, is anticipatory: the optimization of the control of the large (controllable) flood defence structures in the Dutch water system. This is explored in this thesis in the form of the application of Optimal Control, which utilizes Model Predictive Control. This is the only control method which can deal with large interconnected systems, anticipation on predictions, conflicting goals, and constraints. It is a methodology that originates in the process industries and is throughout the world applied to all sorts of systems and processes. More recently it has found its way into water management. A major benefit of this method is that the costs of realisation, operation and maintenance of such a system are estimated to be orders of magnitude lower than taking (extensive) physical measures. In previous studies the influence of the application of Model Predictive Control on the water safety in The Netherlands has been determined for specific cases. However, a probabilistic analysis, which can provide a more complete picture of the profit of this technology in general, i.e. the effect on overall system behaviour, and is required by Dutch law for any measure in order to be considered a potential solution for safety against flooding, has not been possible thus far. In this research a computing platform which allows for parallel calculation is used which makes this analysis possible. In this research, a model framework has been set up allowing for such a probabilistic water safety analysis of The Netherlands using Model Predictive Control. This framework consists of: - a high resolution Sobek Rural model of the rivers, lakes and estuaries of The Netherlands (LSM) which is used to simulate the real world; - Optimal Control in Matlab, which includes an internal model, an objective function and constraints; - Hydra-Zoet probabilistic model to account for the probabilistic analysis. During this research improvements and adaptations have been made to the models used. Using this framework the probabilistic approach has been followed in order to determine the effect of the application of Model Predictive Control. Additionally five structures, selected considering existing plans for the water system and the effect these structures can have on the water distribution, have been added to these models to further investigate possibilities within the system. The effect of Model Predictive Control in this research is determined largely by a minimization of the objective function which includes many locations, structures and goals, each made explicit by weights set in the controller. Before results could be obtained, an iterative process (trial and error) has been gone through in order to determine a best suiting set of weights to be used for this research. The required model calculations for the probabilistic analysis used in this research consist of a limited set of 108 calculations determined by previous research of HKVLIJN IN WATER, these are considered to be representative for the overall system behaviour. This set consist of nine river discharge levels, combined with six storm levels combined with possible (dependant) failing of the Maeslant barrier and Hartel barrier. What can be concluded from the results is that, when applying Optimal Control, clear effects can be expected in certain cases, while in other cases differences with current control are minimal. As a result, the effect on the overall system behaviour (normative water levels) is minimal as all scenarios are considered and effects are levelled out. In the upper rivers water system no differences can be observed as in this water system (almost) no structures exist to influence the water distribution. When the new structures are added to the model, more extensive differences can be observed. The effects of these structures are clear when considering individual cases, however the results in terms of differences in normative water levels are not in line with results obtained from individual cases. More detailed inspection of the results obtained from different parts in the model framework revealed some inconsistencies in the outcomes of the Sobek-calculations, which are probably the cause of the deviating results in terms of normative water levels. Due to the complexity of the model framework and enormous amount of data output such inconsistencies can be easily overlooked. Considering this the results displayed in this research should not be considered representative for the differences in overall system behaviour when the new structures are added to the system. Possibly some inconsistencies still exist for the calculations with current control and Optimal Control without new structures as well. Recommendations have been made for improvements of the model framework and further research, most importantly the addition of the new structures to the objective function.Water Resources ManagementWater ManagementCivil Engineering and Geoscience
Optimization of the rainfall-runoff response in urban areas by using controllable drains
No full textIn the last times, infiltration facilities to reduce the load on the drainage systems have been introduced in many urban areas. These facilities allow water to infiltrate or to drain depending of the level it reaches in the ground. It results easy to conclude that this infiltrating and draining process is likely to be controlled in real time so extra storage can be created on the urban subsurface when necessary or, on the other way round, store water when a shortage is expected. To study the possibilities of controlling the groundwater levels to create extra storage, an area of study was selected in the municipality of Delft, which was interested as well in being able to create extra storage. This area includes an infiltration system. After insight on the area was acquired, the only element which is likely to be controlled in the whole process turns to be the head levels at the infiltration facility. Therefore, it becomes necessary to find the influence the infiltration facility has on the groundwater system on its surroundings and obtain a model which allows tuning a proper controller afterwards. A mathematical model of the response of the groundwater levels within the area of study was created by using system identification. The inputs to this identification process are net precipitation, the historical precipitation and the water level at the infiltration facility. The output is, of course, the groundwater levels. All the data was obtained after a measurement campaign using both “in situ” measurements and remote sensing. Once a proper model was obtained, a simple feedback controller for the infiltration facility levels was tuned. A visible improvement on the groundwater levels behavior was observed when the controlled system was simulated. It results clear then that groundwater levels, within an area where an infiltration facility is present, can becontrolled in theory. A simple actuator was designed and built to be able to run practical experiments in the area later on. With this, the real relation of the infiltration system with the surrounding grounds can be checked as well as different control methods can be tried in further research
Gradient-based hybrid Model Predictive Control using Time Instant Optimization for Dutch regional water systems
No full textThis thesis focusses on Dutch regional water systems. These systems are often low-lying polder-belt canal systems, where many pumps are needed to meet different requirements regarding water quantity and quality. The control of a complex water system, consisting of continuous dynamics (evolution of water flow and levels) and discrete elements (e.g. barriers and pumps that are operated on or off) can be optimized using a so-called hybrid Model Predictive Controller. However, particularly the optimization of the combination of discrete and continuous elements requires extensive computational effort. Even with the ongoing increase in computational power, computational time remains an issue for the optimization of large hybrid systems in real-time control applications. Time Instant Optimization MPC has been proposed in literature as an alternative to the computationally more demanding Mixed Logical Dynamical models. TIO-MPC involves the optimization of a (a priori determined) number of time instants, which are the moments that a discrete variable changes its state. The rationale behind this approach is that in many cases, it is undesirable to have too many switching of controllers. This significantly reduces the amount of optimization variables, as the controller does not have to decide at every time step whether or not to switch the state of discrete variables. The latter would normally lead to a large combinatorial optimization problem. The contribution of this thesis is the extension of the current TIO-MPC in such a way that the time instants become continuous. This way, the gradient of the objective function can be derived. The gradient allows the use of efficient gradient-based solvers, which require a gradient vector of the objective function for finding an optimum. Furthermore, hybrid schemes including the optimization of time instants and standard MPC can easily be integrated. The analytical gradient of the objective function is derived by applying algorithmic differentiation in reverse mode. This way, the gradient of the objective function can be derived to machine precision at the computational costs of a single function evaluation. Another benefit of the use of algorithmic differentiation over finite differencing is the absence of a truncation error. Multiple TIO-MPC algorithms have been designed, and their performance has been tested using two test cases. Different performance indicators are defined and used to compare the results. The first test case involves the closed-loop simulation of a fictitious linear reservoir with one discrete control variable (pump) using two time instants. The second test case involves the pump scheduling of two continuous pumps, two discrete pumps and one a gate on a model of the Fivelingo boezem, an existing water system in the province of Groningen in the north of the Netherlands. For the latter, only open-loop simulations have been carried out using algorithms with a different number of time instants. For comparison, one continuous optimization was done. The gradient-based TIO-MPC algorithms are perfectly capable of optimizing both continuous and discrete elements, well within the allowed control time step. The computational time is correlated with the amount of iterations that is needed to converge to a solution. Therefore it cannot be said in advance which scheme is the quickest. A comparison of the different TIO-MPC algorithms used for the Fivelingo test case demonstrated that the use of more time instants generally leads to lower objective function values, indicating better control performance. The experiments also showed that the solution is likely to get stuck in (suboptimal) local minima if a user-supplied initial guess of the time instants is not given. Supplying a good initial guess or using a multi-start optimization procedure will potentially overcome this problem. The latter option is more realistic if one cannot come up with a good initial guess.Water ResourcesWater ManagementCivil Engineering and Geoscience
Zaffelare : Archeologische prospectie, analyse, synthese /
No full textVerhandeling ingediend tot het bekomen van de graad van Licentiaat in de Geschiedenis: Oudste TijdenV. 1: tekstgedeelteV. 2: dossiers deel 1V. 3: dossiers deel 2V. 4: Annex 1: de verzameling Van Overloop; Annex 2: de verzameling Maertens de NoordhoutV. 5: Notenapparaat en bibliografieV. 6: KaartenGentseHistorischeSchoo
Reading water quality variables with a smartphone
No full textWater ManagementCivil Engineering and Geoscience
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