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The natural coastal hydrodynamics and morphology worldwide is altered by human interventions such as embankments, shipping and dredging, which may have consequences for ecosystem functionality. To ensure long-term ecological sustainability, requires capability to predict long-term large-scale ecological effects of altered hydromorphology. As empirical data sets at relevant scales are missing, there is need for integrating ecological modeling with physical modeling. This paper presents a case study showing the long-term, large-scale macrozoobenthic community response to two contrasting human alterations of the hydromorphological habitat: deepening of estuarine channels to enhance navigability (Westerschelde) vs. realization of a storm surge barrier to enhance coastal safety (Oosterschelde). A multidisciplinary integration of empirical data and modeling of estuarine morphology, hydrodynamics and benthic ecology was used to reconstruct the hydrological evolution and resulting long-term (50 years) large-scale ecological trends for both estuaries over the last. Our model indicated that hydrodynamic alterations following the deepening of the Westerschelde had negative implications for benthic life, while the realization of the Oosterschelde storm surge barriers had mixed and habitat-dependent responses, that also include unexpected improvement of environmental quality. Our analysis illustrates long-term trends in the natural community caused by opposing management strategies. The divergent human pressures on the Oosterschelde and Westerschelde are examples of what could happen in a near future for many global coastal ecosystems. The comparative analysis of the two basins is a valuable source of information to understand (and communicate) the future ecological consequences of human coastal development.

Human infrastructures can modify ecosystems, thereby affecting the occurrence and spatial distribution of organisms, as well as ecosystem functionality. Sustainable development requires the ability to predict responses of species to anthropogenic pressures. We investigated the large scale, long term effect of important human alterations of benthic habitats with an integrated approach combining engineering and ecological modelling. We focused our analysis on the Oosterschelde basin (The Netherlands), which was partially embanked by a storm surge barrier (Oosterscheldekering, 1986). We made use of 1) a prognostic (numerical) environmental (hydrodynamic) model and 2) a novel application of quantile regression to Species Distribution Modeling (SDM) to simulate both the realized and potential (habitat suitability) abundance of four macrozoobenthic species: Scoloplos armiger, Peringia ulvae, Cerastoderma edule and Lanice conchilega. The analysis shows that part of the fluctuations in macrozoobenthic biomass stocks during the last decades is related to the effect of the coastal defense infrastructures on the basin morphology and hydrodynamics. The methodological framework we propose is particularly suitable for the analysis of large abundance datasets combined with high-resolution environmental data. Our analysis provides useful information on future changes in ecosystem functionality induced by human activities., Hydraulic Engineering, Civil Engineering and Geosciences

In the south-western part of the Netherlands, the system of estuaries, tidal basins and islands called the Delta, has been shaped and studied by humans for centuries. By far the largest event that determined its current configuration was the storm surge that occurred in 1953. This giant flooding gave rise to one of the largest engineering programs in the world: the Delta Plan. The aim of this plan was to ensure safety against flooding, while at the same time allow for other utilisations of the Delta. This system of dams, barriers and sluices has had, and is still having a strong effect on the morphology of the Delta coast and basins, especially the Eastern Scheldt tidal basin. The objective of this research is to gain understanding of the mechanisms that govern the exchange of sediment between the Eastern Scheldt basin and its ebb-tidal delta, and the effects of human interventions on these mechanisms. In order to gain better understanding of the processes determining the morphology of the Eastern Scheldt inlet, analysis of bathymetric and hydraulic data is combined with process-based numerical modelling. From this study on the Eastern Scheldt and its surroundings, it has become clear that the Eastern Scheldt is a basin that has been shaped strongly by a multitude of human interventions throughout the past few centuries. It will also take in the order of centuries before the morphological effects of these interventions will have levelled out., Hydraulic Engineering, Civil Engineering and Geosciences

The ebb-tidal delta of the Eastern Scheldt tidal inlet has been under the influence of a storm surge barrier for the past 25 years. This barrier caused a strong decrease in average tidal currents through the inlet. The morphological response of the ebb-tidal delta is characterized by several different processes: (1) an overall decrease in sediment volume and morphological activity, (2) downdrift reorientation of channels and shoals, (3) a redistribution of sediment between channels and shoals, and (4) a lack of sediment exchange with the basin. Simulations with a process-based model show that the reorientation is a result of changed balance between cross-shore and alongshore tidal currents. The sediment volume decrease is a result of decreased tidal currents in combination with wind waves and a lack of sediment supply., Hydraulic Engineering, Civil Engineering and Geosciences

The Eastern Scheldt ebb-tidal delta morphology has been adapting for the past 25 years in response to the construction of the Eastern Scheldt storm-surge barrier in 1986. As a result of the barrier, there has been a decrease in tidal amplitudes, volumes, and average flow velocities, and there is hardly any sediment exchange through the barrier. Bathymetrical measurements of the ebb-tidal delta show multiple effects: (1) an overall decrease in sediment volume, (2) a decrease in morphological activity, (3) sedimentation in most channels, (4) northward reorientation of channels and shoals, and (5) an increase in wave-driven features. Some channels are showing stronger erosion since 1986. This, and the reorientation of other channels could be related to changes in the interaction between crossshore and alongshore tide. Most of the erosion is located in shallower, wave-dominated regions, indicating that waves have become relatively stronger. The steady erosive trend, combined with the decline of morphological activity, points toward a system dominated by relatively small and mostly negative bed-level changes. This system is still far from any kind of equilibrium, and is steadfastly adapting itself to the new hydraulic forcing regime, even though sediment transport capaci ies have decreased, Hydraulic Engineering, Civil Engineering and Geosciences

The Eastern Scheldt tidal basin has changed drastically in the past five centuries under the influence of both human interventions as well as extreme events. In 1530 A.D. a storm-surge inundated large parts in the landward end of the basin, and in the following four centuries local inhabitants reclaimed about as much land as was inundated in that storm. To investigate the effects of these processes on basin morphology, several different simplified geometries of the basin are used in order to gain insight into the evolution of the tidal currents over the centuries. From this model it appears that the large-scale inundations cause the basin to scour to greater depth. This in turn causes the ebb-tidal delta to grow, and causes the disappearance of the tidal watershed between the Eastern Scheldt and the Grevelingen tidal basins. Land reclamations have not been able to turn these trends around., Hydraulic Engineering, Civil Engineering and Geosciences

A promising new method for measuring sediment properties in the field is called MEDUSA RhoC. This device measures mud and sand content, sediment density, and water content in the field using Radiometric Sedimentology. The aim of this thesis is to investigate the accuracy and applicability of the MEDUSA RhoC system with its new components. This is done by comparing results obtained with the RhoC to results obtained with traditional analyses, both in the lab and the field. Besides this, also the general characteristics of natural sediments are investigated in order to see what other properties can be derived from mud content, sediment density and water content alone. The radiometric activity of sediment is related to its mud content. The MEDUSA RhoC system determines mud content by measuring the radio-activity of sediment, and translating the activity to mud content. The relation between mud content and activity concentration is called the radiometric fingerprint. Depth averaged sediment density is determined by pushing a radio-active source into the soil, and measuring the attenuation of the activity coming from the source. The water content is determined with a technique known as Time Domain Reflectrometry. To investigate the performance of the RhoC under controlled circumstances, tests are performed in the laboratory and field. The field tests of the RhoC are performed on tidal flats in the Western Scheldt. On several locations in the Western Scheldt the RhoC is used to measure radiometric activity, density profile, and water content. At the same locations, sediment cores are collected. These samples are taken to the laboratory to determine sediment density, water content, grain size distribution, organic matter content, and radiometric activity concentration. This is done using "ordinary" techniques. The laboratory analyses on the sediment samples taken from the Western Scheldt show several relations between various sediment properties. The RhoC measures only the, Civil Engineering and Geosciences

Master project report. In the year 2004 there was a flooding in an area between Da'an River and Dajia River in Taichung County, Taiwan. The flooding was caused by outlets which were clogged up, thus lacking the capacity to discharge the amount of rainwater that the typhoon caused into the sea. A survey conducted by the project group, showed that the coastal protection is deteriorating, aging and inconsistent. Therefore the safety of the coastal protection is doubtful when extremely high water tables occur. The survey also showed that most of the outlets did not function properly, either they were clogged up, or the outlets were forced open by local inhabitants, using stones or tree-trunks. The main purpose of this project is to design a new coastal protection and drainage system, which will suffice in their main purpose, but are also sound with the ecological, recreational and spatial requirements. The alternative solutions consist out of three elements. These elements are the possibility of land reclamation, the possible methods of coastal protection and methods of drainage. There exists a strong relation between the elements. After the feasibility of land reclamation was considered, four categories of solutions concerning the coastal protection were treated: "do nothing", improvement or replacement of the current dike, offshore constructions and soft solutions. Concerning the drainage system the following categories are treated: allowing flooding (do-noting alternative), decrease of the peak discharge or structural enhancement of the capacity. It was concluded that land reclamation is a feasible option and has to be further elaborated because of the favorable conditions of the foreshore and opportunities for land use. By using a multi-criteria analysis a choice has been made out of the generated alternatives. This analysis has shown that dike improvement and/or the application of soft solutions are preferred for coastal protection. The use of detention and the rem, Hydraulic Engineering, Civil Engineering and Geosciences

Combinations of organophosphorus insecticides (chlorpyrifos-methyl or fenitrothion) with pyrethroids (deltamethrin or bioresmethrin) or an insect growth regulator (methoprene) were applied to paddy rice and tested against a multi-resistant strain of Sitophilus oryzae (L). The aims of the study were to determine whether there were significant interactions between the grain protectants and whether such interactions would lead to substantial changes in field application rates. In bioassays of freshly treated paddy, there were significant positive interactions in the following combinations: chlorpyrifos-methyl + deltamethrin, chlorpyrifos-methyl + synergised deltamethrin, chlorpyrifos-methyl + synergised bioresmethrin, fenitrothion + deltamethrin, and fenitrothion + synergised deltamethrin. This synergism was evident in terms of number of adult F1 produced as well as mortality of parents. There was no interaction between chlorpyrifos-methyl and methoprene. The treatments chlorpyrifos-methyl 0.625 mg kg−1, deltamethrin 2 mg kg−1 and deltamethrin 0.25 mg kg−1 + piperonyl butoxide 8 mg kg−1 each produced negligible mortality, but the combinations chlorpyrifos-methyl 0.625 mg kg−1 + deltamethrin 2 mg kg−1 and chlorpyrifos-methyl 0.625 mg kg−1 + deltamethrin 0.25 mg kg−1 + piperonyl butoxide 8 mg kg−1 produced > 60% mortality. Similarly, mortality was 0% for fenitrothion 10 mg kg−1, deltamethrin 2 mg kg−1 and deltamethrin 0.25 mg kg−1 + piperonyl butoxide 8 mg kg−1, but the combinations fenitrothion 10 mg kg−1 + deltamethrin 2 mg kg−1 and fenitrothion 10 mg kg−1 + deltamethrin 0.25 mg kg−1 + piperonyl butoxide 8 mg kg−1 produced > 80% mortality. In long-term experiments mixtures of chlorpyrifos-methyl and deltamethrin or deltamethrin + piperonyl butoxide 8 mg kg−1 were evaluated during up to 24-weeks storage (30 °C, 70% r.h.) following treatment. Strong synergism was evident in tests of freshly treated paddy, but deltamethrin or deltamethrin + piperonyl butoxide had little o