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Anthropogenic changes to estuaries, usually highly productive systems, may result in increased turbidity levels, suppress pelagic primary production and negatively affect ecosystem functions. The Ems-Dollard estuary, enclosed between the Netherlands and Germany, is such an estuary with a long history of human induced changes. From the mid-19th century until 1992, discharges of potato starch and strawboard industry waste water, with high contents of organic matter, negatively affected oxygen concentrations and increased nutrient levels of the system. The growing awareness of the deteriorating effects of these discharges on the ecosystem invoked a large research program, BOEDE, between 1976 and 1980. The aim of the current paper was to establish the recent gross pelagic primary production, to compare the results with the late seventies data and to relate possible changes to environmental variables such as suspended matter and nutrients. To this end, six stations from the North Sea into the inner area of the Dollard were visited 39 times in 2012–2013. During each sampling cruise, a so-called PocketBox, containing a number of sensors, provided a high spatial data resolution between stations. At each station, samples were collected for carbon fixation incubations using 14C. Average chlorophyll-a concentrations as reported in this study were lower compared to 1978–1980 for the seaward stations, and higher for the most inward station in 2012 and almost similar in 2013. Light attenuation coefficients in the outer areas were lower in 2012–2013 (1.22 m− 1) compared to the values reported in the period 1976–1980 (1.59 m− 1), indicating somewhat less turbid conditions. For the two other stations, light attenuation coefficients in the present study were similar to the late seventies’ values, for the station near the entrance of the Ems River in the Ems-Dollard area, the coefficient was substantially higher. Pelagic primary production in the 2012–2013 period was about 120 g C m− 2 y− 1, mainly determined by the most seaward areas. The largest differences in gross primary production in the current study compared to the 1976–1980 period were found at the seaward stations where production in the late seventies was about 60% higher. In the Dollard-area, production hardly changed since the late seventies, but also stations near the Ems-river entrance into the Ems-Dollard area showed a clear decrease. Changes at the inward stations are to be contributed to an increased turbidity; the decrease at the outer areas to a decreased nutrient level, especially dissolved phosphorus and silicate, but possibly also nitrogen.
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This report bundles the annexes for the data report of the overflow tests executed on the Dutch part of the Hedwige-Propserpolder levees. Overflow tests on levees are designed to test the strength of levees and levee covers under the load of a continuously overflowing discharge of water. For this purpose, Flanders Hydraulics Research have designed and built an Overflow Generator (Vercruysse et al., 2022) within the framework of the Polder2C’s project. This device allows to generate a controlled and homogenous discharge of water over the levee crest. Within the Polder2C’s project, 25 overflow tests on Belgian and Dutch levee stretches have been executed in 3 episodes from 30/10/20 to 28/11/20, 17/02/21 to 31/03/21 and 16/11/21 to 20/12/21. Different test goals have been addressed, to understand the normal performance of a levee cover, and the influence of different anomalies and/or deviations from the ‘standard’ levee.
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Report on testing of water overflow on Dutch levees. On the Dutch part of the levee in Hedwige-Prosperpolder, 11 overflow tests have been conducted. Overflow tests on levees are designed to test the strength of levees and levee covers under the load of a continuously overflowing discharge of water. For this purpose, Flanders Hydraulics Research have designed and built an Overflow Generator (Vercruysse et al., 2022) within the framework of the Polder2C’s project. This device allows to generate a controlled and homogenous discharge of water over the levee crest. Within the Polder2C’s project, 27 overflow tests on 11 Belgian and 11 Dutch levee stretches have been executed in 3 episodes from 30/10/20 to 28/11/20, 17/02/21 to 31/03/21 and 16/11/21 to 20/12/21. Different test goals have been addressed, to understand the normal performance of a levee cover, and the influence of different anomalies and/or deviations from the ‘standard’ levee.
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Coastal realignment is the procedure of repositioning or removing coastal defense structures to restore tidal flooding and facilitate the development of intertidal ecosystems in a previously reclaimed area from the sea. A key policy objective of coastal realignment is to increase ecosystem services provided by intertidal ecosystems and thereby contribute to human well-being. However, the social response to coastal realignment is often negative, raising the question as to what extent communities living nearby project locations recognize, value and benefit from the goods and services provided by restored intertidal ecosystems. In this study, we examine public perceptions of ecosystem services gains, losses and trade-offs associated with coastal realignment. We hereby focus on three coastal realignment case study locations in the Southwest delta, the Netherlands. Questionnaires were administered in nearby villages and the collected data (N = 261) were analyzed using random forest regression models. A notable outcome of this study is that local communities often consider coastal realignment interventions to decrease rather than increase the availability of ecosystem services. This points to a discrepancy between how coastal realignment is viewed from a policy perspective and a local community perspective. Changes in the availability of cultural ecosystem services were found to have the highest impact on the level of support for coastal realignment, while the importance attached to provisioning, regulating and supporting ecosystem services was notably lower. In consequence, to increase public support, it will be essential to minimize the loss of cultural ecosystem services, or better yet, find ways to increase cultural ecosystem services through coastal realignment, for instance by creating opportunities for recreation and tourism.
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Animal burrows create discontinuities on the body of earthen levees that under certain circumstances can threaten their structural integrity through hydraulic alteration and surface erosion. Although it is a virtually established fact that discontinuities can undermine the structural integrity of levees, there are limited studies that clarify when animal activity can be considered dangerous and which are the most effective approaches for dealing with it. Interaction with levee management agencies in the network of Polder2C’s has shown that there is much tacit knowledge on the topic among levee guards in the Netherlands, Belgium, France and the UK, which has only been marginally reported so far. It is also of interest that the Dutch Government approved the inclusion of measures against harmful animal activity in flood defences more than a decade ago (Tweede Kamer 2010), but to this end, an integrated national management framework is still pending. This highlights the fact that formal knowledge on the topic is limited and fragmented. In order to enable the development of a rational framework for dealing with animal activity on levees, a coordinated effort is required for the review and reporting of existing knowledge, identification of knowledge gaps and development of approaches to determine the level of risk incurred by various types of animal activities on levees and the effectiveness of reduction actions. This report presents activities that took place within Polder2C’s and could support the development of such a rational framework. After the first winter of experimentation in the Living Lab Hedwige-Prosperpolder, evidence was produced about possible adverse impact of animal- and vegetation-induced discontinuities on levees (Holscher & Zomer, 2021; Koelewijn et al. 2021). Overflow experiments at locations of anomalies caused by grazing sheep, trees and fox holes led to severe erosion of the structure within a considerably short time (see also Figure 1.2a). In June 2021 a mole burrow system was detected in a levee section that had been damaged during overflow experiments and where an emergency repair application with rock bags had been subsequently applied. In order to explore the geometry and extent of the system, the mole tunnels were grouted with fast drying concrete. Upon excavation of the concrete an extensive burrow system was revealed with exit points close to the toe and close to the crest of the section (see also b). In preparation of the second winter of experimentation, a cross-work package team was created to identify knowledge gaps in the management of animal burrows on levees and suggest research activities that could potentially fill in identified gaps. This led to a longlist of possible activities, a number of which were eventually executed in the period September 2021 till February 2022. The final selection of activities was limited by the contractor’s work and other large-scale experiments and exercises. Priority was given to activities that had no conflicts with the abovementioned operations and for which there was available equipment and manpower within the involved organizations. This report presents the work that was performed within Polder2C’s on the management of harmful animal activity on levees in a chronological order. It starts with a description of observations in the first year of the project, and a subsequent study that led to the development of a knowledge agenda in the period February till June 2021. It continues with a description of activities that took place in a more coordinated manner in the second year of the project and it ends with a summary of key findings.
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Report on testing of water overflow on Belgian levees. On the Belgian part of the levee at the Prosperpolder, 14 overflow tests have been conducted on 12 sections. Continuous overflow tests on levees are designed and executed to test the strength of levees and levee covers under the load of a continuously overflowing discharge of water. For this purpose, Flanders Hydraulics has designed and built an Overflow Generator (Vercruysse et al., 2022) within the framework of the Interreg Polder2C’s project. This device allows to generate a controlled and homogenous discharge of water flowing over the levee crest and slopes. Within the Polder2C’s project, 27 overflow tests on Belgian and Dutch levee stretches have been executed in 3 episodes from 30/10/20 to 28/11/20, 17/02/21 to 31/03/21 and 16/11/21 to 20/12/21. Different test goals have been addressed, to understand the normal performance of a levee cover, and the influence of different anomalies and/or deviations from the ‘standard’ levee.
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This report bundles the annexes for the data report of the overflow tests executed on the Belgian part of the Hedwige-Propserpolder levees. Overflow tests on levees are designed to test the strength of levees and levee covers under the load of a continuously overflowing discharge of water. For this purpose, Flanders Hydraulics Research have designed and built an Overflow Generator (Vercruysse et al., 2022) within the framework of the Polder2C’s project. This device allows to generate a controlled and homogenous discharge of water over the levee crest. Within the Polder2C’s project, 27 overflow tests on Belgian and Dutch levee stretches have been executed in 3 episodes from 30/10/20 to 28/11/20, 17/02/21 to 31/03/21 and 16/11/21 to 20/12/21. Different test goals have been addressed, to understand the normal performance of a levee cover, and the influence of different anomalies and/or deviations from the ‘standard’ levee.
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This booklet shows the urban metabolism of five different cities around the globe. From small, Venice, to extra large, New York. We took the city as the human body; integral, dependent on multiple organs and based on comprehensive flows. Mobility, typology, nature and history go hand in hand in the total package that shaped each city to what it is nowadays. Second year students Urbanism O2a (2020): Iaroslava Nesterenko, Oswin Noordergraaf, Wout Velthof, Roelof Koudenburg, Saskia Kleij, Boris von der Möhlen, Lennart Barnhard, Romy van den Berg, Samer Fadel, Hyunwoo Koo, Madelon Jansen. They studied their city on the hand of the following themes 1. Metropolitan Size and Positioning 2. Relation Infrastructure and Landscape 3. Urban Typology 4. Public Space 5. City Centers 6. Relation Between History and Growth 7. Covid-19 outbreak 8. Bonus drawings
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This report provides an overview of the initiatives that were taken to disseminate information, lessons and knowledge acquired during Polder2C’s via formal educational programmes and an evaluation of the extent that project findings have been embedded in educational curricula of relevant partner organisations.
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Managed realignment (MR) involves repositioning coastal or river flood defenses to re-establish tidal flooding and restore intertidal ecosystems in reclaimed areas. The restoration of intertidal ecosystems contributes to flood risk management and achieving nature conservation objectives. However, MR often faces resistance from local communities, potentially undermining its implementation. Previous qualitative studies have discussed the role of socio-psychological constructs in shaping public attitudes toward MR, but quantitative empirical assessments grounded in socio-psychological theory are scarce. In addition, the absence of comparative research across multiple cases limits the potential for generalization, making it difficult to apply findings to other contexts and populations. This study contributes to filling these research gaps by examining socio-psychological constructs that shape public support for MR in three case study areas in the Netherlands. We administered questionnaires among households (N = 324) and used multivariate and regression models to analyze the collected data. Results across the case studies point to three socio-psychological constructs that consistently explain public support for MR, including (i) trust in institutions, (ii) outcome expectancies and (iii) emotions. These constructs are intercorrelated, suggesting that they influence each other when collectively shaping support for MR. Strategies to enhance public support could be more effective when they address these constructs in an integrated manner. Moving forward, it is important to explore how public engagement and communication around MR policies could be tailored to leverage positive emotions better and how the design of MR can be aligned with location-specific priorities.
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