Dutch Polders Research Articles

Optimal salinity and water level control of water courses using Model Predictive Control

Worldwide, delta areas are under stress due to climate change. With rising sea levels and decreasing freshwater availability, surface water salinization due to groundwater exfiltration is expected to increase in these low-lying areas. To counteract surface water salinization, freshwater diverted from rivers is used to flush agricultural ditches. In this paper, we demonstrate a Model Predictive Control (MPC) scheme to control salinity and water levels in a water course while minimizing freshwater usage. A state space description of the discretized De Saint Venant and advection-dispersion equations for water and salt transport, respectively, is used as the internal model of the controller. The developed MPC scheme is tested using groundwater exfiltration data from two different representative Dutch polders. The tests demonstrate that water levels and salinity concentrations can successfully be controlled within set limits while minimizing the freshwater used.

Land subsidence by peat oxidation leads to enhanced salinization through boils in Dutch polders

Peat oxidation in deep Dutch polders leads – in addition to subsidence - to the development of new saline boils, enhancing the salinization of these polders. This on-going process is studied in detail in the Middelburg-Tempelpolder. The objective of the study was to get more in-depth knowledge about this process and to assess it for the present situation and for future landscapes (after 10, 50, 100 and 500 years).

To fly or not to fly: Factors influencing the flight capacity of carabid beetles (Coleoptera: Carabidae)

This review considers factors affecting the flight capacity of carabid beetles and the implications of flight for carabids. Studies from the Dutch polders in particular show that young populations of carabids consist predominantly of macropterous species and macropterous individuals of wing-dimorphic species. Also populations of wing-dimorphic carabid species at the periphery of their geographical range contain high proportions of macropterous individuals. However, studies from Baltic archipelagos show that older populations of even highly isolated island habitats contain considerable proportions of brachypterous species and individuals. This suggests that macroptery is primarily an adaptation for dispersal and that there exists a mechanism for subsequently reducing the ratio of macropterous to brachypterous species under stable conditions, due to the competitive advantage of brachyptery. Populations in isolated habitats, such as islands and mountains, have high proportions of brachypterous species. Many macropterous species do not possess functional flight muscles. Species of unstable habitats, such as tree canopies and wet habitats, are mostly macropterous. Brachypterous species tend to disappear from disturbed habitats. There is uncertainty regarding the extent to which carabid dispersal is directed and how much passive. Both Den Boer and Lindroth recognized that mostly macropterous individuals of macropterous and wing-dimorphic species disperse and found new populations, after which brachyptery tends to rapidly appear and proliferate in the newly founded population. It is most likely that the allele for brachyptery would arrive via the dispersal of gravid females which had mated with brachypterous males prior to emigration. Whilst many studies consider wing morphology traits of carabid beetles to be species-specific and permanent, a number of studies have shown that the oogenesis flight syndrome, whereby females undertake migration and subsequently lose their flight muscles by histolysis before eventually regenerating them after reproducing, has been reported for a growing number of carabid species. Wing morphology of carabid beetles clearly offers strong potential for the study of population dynamics. This field of study flourished during the 1940's to the late 1980's. Whilst a considerable amount of valuable research has been performed and published, the topic clearly holds considerable potential for future study.

Resilience trade-offs: addressing multiple scales and temporal aspects of urban resilience

The concept of urban resilience has so far been related mainly to climate change adaptation and disaster management perspectives. Here we aim to broaden the discussion by showing how the framework of urban resilience should be related to wider sustainability challenges, including i) climate change and natural hazard threats, ii) unsustainable urban metabolism patterns and iii) increasing social inequalities in cities. Using three case studies (flood risk management in the Dutch polders, urban–rural teleconnections driving the Bolivian quinoa market, and spatial diversity in the adaptive capacity of Kampala slums),(1) we draw out significant insights related to scales and sustainability, which will push urban resilience research forward. The key “move” is to consider both spatial and temporal interactions, in order to shift from the mainstreaming of the resilience-building paradigm toward a critical understanding and management of resilience trade-offs. While urban resilience emerges not necessarily as a normatively positive concept anymore, we argue that addressing multi-scale and temporal aspects of urban resilience will allow greater understanding of global sustainability challenges.

A novel method of wind energy generation-the electrostatic wind energy converter

Since ancient times humanity has been harnessing the power of the wind in various forms, such as discovering the planet in sailboats, creating living space in the Dutch polders, or providing bread by flour-grinding windmills. Since 1887 wind has also been used to generate electricity as the shift to renewable energy production is being made [1]. In order to fulfill the long-term carbon emission goals set by, for example, the EU for 2050, the share of renewable energy (wind, solar, hydro, biofuels) needs to increase substantially [2]. Of these various means of renewable energy, wind energy is still the largest part. Therefore, wind farms, both decentralized and bulk, are being constructed. In 2010 wind energy constituted 2.5% of the global electricity production [3]. The article explores a novel method of wind energy generation using an electrostatic wind energy converter or EWICON.

Natural saltwater upconing by preferential groundwater discharge through boils

Natural saltwater upconing caused by the preferential groundwater discharge of boils is a key proce ss in the salinization of Dutch deep polders. The factors controlling upconing by boil discharge and boil water salinities are poorly constrained and have not been previously documented. We addressed this knowl- edge gap by investigating upconing mechanisms using field measurements and numerical simulation s of simplified situations. Boils occur as conduits in the upper aquitard connecting the underlying aquifer to the surface and allowing groundwater to discharge at rates up to 100 m3 d?1 with Cl concentrations up to5gL?1. Boils are found as isolated features or clustered in small areas of 20–100m2. Field observations show that preferential flow through boils creates localized and narrow saltwate r upconing spikes, caus- ing the elevated boil water salinities. Modeling results indicate that boil water in Dutch polders com- prises mixtures of groundwater from a wide range of depths and salinities with larger contributions from shallower and less saline groundwater than from the deeper and more saline water. Similar to pre- vious numerical studies of pumping-in duced upconing, the numerical results show that the most impor- tant factors controlling the boil salinity in Dutch polders are boil discharge, the horizontal hydraulic conductivity of the aquifer, the depth of the transition zone and the salinit y (or density) contrast within the aquifer. When boils are clustered, natural saltwater upconing is a function of the total discharge of a boil cluster, whereas the boil-to-boil salinity variations within a cluster are determined by the discharge of individual boils and their position relative to neighboring boils. Regional lateral flow significantly mod- ifies flow patterns by dividing the groundwater flow system into a local boil system overlying the regio- nal flow system. Despite this, regional flow has only a minor effect on the relative contribu tions of saline and fresh groundwater to boil discharge and thus on boil salinity as well.

Climate adaptive urban planning and design with water in Dutch polders

The existing water management in Dutch polders is based on independent water systems for each polder. These are featuring artificial stabilized ground and surface water levels. As a result of the local climate the water levels in the polders are not continuously at a constant level. To maintain a stable water table in the polders, the surplus of relatively clean rainwater has to be pumped away during the cold seasons into canals or rivers, which are located on a higher level. During the summer relatively polluted water from these waterways is led into the polders to top up the declining water levels. This procedure leads to various problems regarding water quantity and water quality. The described existing system is not adaptable to climate change and includes the risk of flooding, particularly from torrential rain. Therefore it is crucial to develop, preferably self-sufficient, rainwater management systems in the polders. They should allow the fluctuation of the water levels inside the polders for seasonal storage and flood control. The described concept is adopted in the present water policy in the Netherlands as well as in research and recent urban development projects in Dutch polders.

Geoarchaeological prospection of a medieval manor in the dutch polders using an electromagnetic induction sensor in combination with soil augerings

AbstractIn archaeological prospection, geophysical sensors are increasingly being used to locate buried remains within their natural context. To cover a large area in sufficient detail, an electromagnetic induction sensor can be very useful, measuring simultaneously the electrical conductivity and the magnetic susceptibility of the soil (e.g., Geonics EM38DD). In this study, an 8 ha field containing a Medieval manor was mapped in a submeter resolution, using a mobile sensor configuration equipped with a GPS. As different soil features can yield analogous responses, the interpretation of geophysical maps can be ambiguous. Therefore, soil auger observations were laid out along two perpendicular transects to provide vertical profiles across the sensor measurements. This information greatly enhanced the interpretation of the anomalies obtained by the sensor. Both natural and anthropogenic features were delineated, which clearly presented a moated site along a former tidal channel. © 2008 Wiley Periodicals, Inc.

René Dubos and Jared Diamond dream of Dutch polders

‘Optimism, despite it all’ is the title of the last chapter of the last book written by Rene Dubos, the greatest of 20th century public health writers.1 Dubos was born in 1901 in France, studied agronomics, and emigrated to the United States in 1924 to start a career in microbiology. He is most known for his writings about ecology and human health. He received the 1969 Pulitzer prize for his bestselling So Human an Animal , in which he argues how man is profoundly shaped by his environment.2 Everybody knows his famous dictum ‘Think globally, act locally’. This idea was developed in the 1970s, in response to the concern of American students with environmental and social problems. They were advised by Dubos to first consider more local situations. ‘If we really want to contribute to the welfare of humankind and of our planet, the best place to start is in our own community, … Correspondence: Johan P. Mackenbach, Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 1738, 3000, DR Rotterdam, The Netherlands, e-mail: j.mackenbach@erasmusmc.nl

Thinking the unthinkable – the end of the Dutch river dike system? Exploring a new safety concept for the river management

Since 1100 the Dutch relied on their continuously expanding extensive dike system for keeping dry feet and dry goods. But how durable and safe is this traditional dike concept, now the sea-level is rising and rainfall patterns seem to change? Can they continue to raise their dikes in the future or should they give more room to the river? In the Dutch mind higher dikes are saver. In practice, however, higher dikes may lead to higher risks as the consequences of failure rise. What is wrong with the risk perception of the Dutch citizen? How should risks be communicated to the public, how should a public debate on safety regimes be organized? In a study project a new safety concept in which the Dutch rivers got a free flow was explored and communicated. In an effort to reframe the issue a transition path, scenarios, impact studies and ex ante evaluations of this new safety management regime were made. A new safety paradigm seems to be taking shape. Context scenarios show under what circumstances frequent flooding can be made acceptable to the Dutch citizen and the inhabitants of the Dutch polders.

15 m diameter tunnelling under Netherlands Polders

In order to become part of the Trans-European network of high-speed rail links, Netherlands is working on the transport of the future: a high-speed link (HSL) between Amsterdam and the Belgian border, connecting the Dutch capital with Antwerpen, Brussels and Paris. A solution with a bored tunnel was chosen to minimize the line's impact on the characteristic fenlandzGM4PIHNgpiv landscape of the Groene Hart (the Green Heart of Holland, situated between The Hague, Amsterdam, Utrecht and Rotterdam). Seven kilometers long (8.5 km including approaches), under the Dutch polders, the tunnel will allow the line to follow the fastest route between Amsterdam and Rotterdam while leaving the countryside largely undisturbed. Designed as a single tube, with a bi-directional train circulation, this tunnel, almost 15 m diameter was constructed with the help of Aurora, the specially designed world largest confining tunnel boring machine (TBM). Yet the realization of such an impressive tunnel required an accurate and efficient risk management policy. This papers deals with the treatment of one particular risk, due to the specific hydro geological conditions of the project, that is to say boring under polders. Aurora, as a slurry shield-boring machine, generates excess pore pressure (EPP) in the soil during the boring process. This EPP phenomenon is originated by the dissipation of the confining slurry overpressure in the cutter head chamber amplified by an accumulation process taking place in a captive aquifer as in the Groene Hart tunnel. This phenomenon was early identified as a potential risk for the project, as the generation of excess pore pressure may induce local instability in the impermeable peat layer and thus connections between the brackish captive water table and the free water table. As the first aquifer piezometric level is higher than the ground level, there is a risk of flooding the polder situated above the tunnel. Even if the communication between the two aquifers is not sufficient to get to this point, the inflow of brackish water in the free water table is a risk as the lands above the tunnel are mainly intended for agriculture. Therefore, a first measurement campaign was implemented very early in the tunnel progression and showed that the phenomenon was of such a magnitude that the risk could not be neglected. A second instrumented plot was thus implemented, to be able to improve the knowledge and understanding of the phenomenon, qualitatively as well as quantitatively. The plot instrumentation was formed of 11 settlement points, 19 pressure cells and two extensometers. The measurement period extends from February 4th to March 11th (2003) (i.e., they cover the boring of about 600 m tunnel length). The experimental results associated with 3D transient numerical modeling, by allowing a better understanding of the phenomenon, gave the tool to identify the risk level and determine the required mitigation measures. This analyze of the phenomenon proved to be accurate as Aurora passed the identified risk area without any trouble, and the last measurements in the risk area are concordant with the predicted settlement and pore pressure levels. (A). Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.

Inundation of a Dutch river polder, sensitivity analysis of a physically based inundation model using historic data

The inundation model Delft flooding system (Delft‐FLS) was applied to simulating the historical flood of 1805 in the polder Land van Maas en Waal (Netherlands). Delft‐FLS is a two‐dimensional (2‐D) hydrodynamic model that simulates overland flow. Sensitivity analyses show a large influence of floodplain topography and hydraulic friction on the propagation of the inundation. Because of the typical topography of Dutch polders, a virtually flat floodplain bordered by high dikes, the extent of the inundated area alone cannot be used for evaluating the model performance. Therefore the inundation time and water levels within the inundated area were used to test the model capabilities. This study shows that using historic data has a potential advantage over using contemporary data. Historic data allow evaluation of a model for real flood disasters that have long return periods and, fortunately, have not occurred in modern times.

Fighting for Canada; Seven Battles, 1758-1945

hat a delight this book is! I must confess, I felt much like a gourmand surveying a groaning table as I considered the mouthwatering, historical delicacies spread before me. Where to begin? The defence of NouvelleFrance? Armoured combat in Normandy? The Canadian infantryman’s war in the Dutch polders, the South African veldt or the Niagara farmlands? In any event, I started where best — at the beginning.

OPTIMAL MAINTENANCE DECISIONS FOR DIKES

To protect the Dutch polders against flooding, more than 2500 km of dikes have been constructed. Due to settlement, subsoil consolidation, and relative sea-level rise, these dikes slowly sink “away into the sea” and should therefore be heightened regularly (at present, every 50 years). In this respect, one is interested in safe and cost-optimal dike heightenings for which the sum of the initial cost of investment and the future (discounted) cost of maintenance is minimal.For optimization purposes, a maintenance model has been developed for dikes subject to uncertain crest-level decline. On the basis of engineering knowledge, crest-level decline has been modeled as a monotone stochastic process with expected decline being either linear or nonlinear (i.e., linear after transformation) in time. For both models and for a particular unit time, the increments are distributed according to mixtures of exponentials.In a case study, the maintenance decision model has been applied to the problem of heightening the Dutch “Oostmolendijk.”

Colonization of new habitats by earthworms.

In this paper a simple model is used to study the dispersal of earthworm populations into new habitats. Simple models do not describe processes accurately, but can help gain insight into the functioning of ecosystems or processes in ecosystems. Using information on reproduction, survival and dispersal at the level of the individual, the velocity of earthworm population expansion was calculated. Dispersal of earthworms can be active or passive. The parameters of active and passive dispersal were calculated from field experiments in one of the Dutch polders. Parameters of reproduction and survival were estimated from published data. The effects of processes at the individual level on the velocity of population expansion were studied for two species (Aporrectodea caliginosa and Lumbricus rubellus). The model shows that passive transport has a major influence on the velocity of population expansion, which is strongly increased even if this transport involves only a very small part of the population. At a high level of passive transport, however, death induced by this mode of dispersal can have a negative influence on population expansion. In the discussion it is indicated that optimising growth conditions of the earthworms might be the easiest way to promote population expansion. However, promoting dispersal by passive mechanisms can also be very important.

Water quantity management in Dutch polders, adversely affecting the recruitment of northern pike (Esox lucius L.)

Water quantity management in Dutch polders, adversely affecting the recruitment of northern pike (<i>Esox lucius</i> L.)

Colonization of Road Verges in three Dutch Polders by Plants and Ground Beetles (Coleoptera: Carabidae)

Colonization of Road Verges in three Dutch Polders by Plants and Ground Beetles (Coleoptera: Carabidae)

Immigration Rates of Plant Species in Three Dutch Polders

We describe the immigration rates of plant species from road verges in three large inland polders in The Netherlands. These rates depend on the dis- persal capacities of the species. As a result, the composition of the vegetation is correlated with the age of the road and the distance from the mainland.

The Fenghsien Landscape: A Fragment of the Yangtze Delta

TEWENTY miles south of Shanghai, near the edge of the growing Yangtze delta, lies the crowded county of Fenghsien. On one side is the ocean, from which the land has persistently been snatched. On the other is the exotic metropolis of Shanghai,1 singularly out of harmony with this ancient agricultural countryside. Above Fenghsien fly the planes of the air service from Shanghai to Canton. As viewed from the air, the most striking features of the flat, green landscape are the micropattern of the fields and the net of closely spaced canals. Other areas may have an equal intensity of agriculture, but in few parts of the world is there a similar development of canals and ponds. In one measured square mile there are no less than 27.8 linear miles of these waterways, and the average spacing is only 380 feet.2 It is these that give the area its distinctive stamp and make the geography essentially hydrography. From the air one may see the lines of maritime dikes bordering the silt-laden sea, which protect the land from high tides. These barriers enclose successively reclaimed areas similar to the Dutch polders. Within the newer dikes the canals are laid out in rectilinear plan, in contrast with the irregular pattern in the older land, west of the innermost, and older, dikes. Scattered clusters of broadleaf trees and bamboo surround groups of farmhouses, and one is seldom out of sight of a market town. Flagstone trails take the place of roads, for there are no carts and few wheelbarrows. Passenger and freight boats move slowly along the larger waterways; smaller farm boats carry fertilizer or produce over the smaller canals. Outside the dikes, along the shore, are numerous salterns, where thousands of evaporating trays are spread