Tauw Group (Netherlands)

Massive open online courses (MOOCs) have emerged as powerful educational tools for disseminating complex scientific knowledge. This study examines the RECONECT MOOC, an innovative online learning platform designed to educate stakeholders about nature-based solutions (NbS) for hydrometeorological risk reduction. Developed by a multidisciplinary team of international experts, the course drew on diverse professional and geographical perspectives, across a range of national and sectoral contexts. Its primary aim to bridge the knowledge gap in climate adaptation strategies across diverse professional sectors. The research investigated the effectiveness of interactive, multimedia-based learning approaches in communicating advanced NbS concepts. Using the Sharable Content Object Reference Model (SCORM) framework, the course integrated multiple learning methods, including reading, listening, inquiry-based learning, discussion forums and practical application exercises. The MOOC was divided into six modules and targeted local authorities, policymakers, academics, postgraduate students and other stakeholders interested in climate resilience. Findings revealed that 90% of participants gained additional NbS knowledge, 69% reported a shift in perception and 62% felt confident applying what they learned. Participants valued the interactive resources and flexible, self-paced format. Overall, the study demonstrates that MOOCs can effectively support scientific knowledge dissemination and strengthen understanding of complex environmental solutions.

Accurate prediction of subsurface flow under uncertain, spatially varying conditions remains a core challenge in hydrogeology. This, in turn, has great impacts on our ability to predict and control contaminant transport in subsurface water bodies and control the dynamics of water quality. This work extends a Physics-Informed Neural Network (PINN) framework to incorporate 1) Function-Guided (Parametric Stochasticity) and 2) Latent-Encoded (Generated Stochasticity) heterogeneities. In the former, a parametric function with random inputs generates multiple heterogeneous media, enabling transfer learning to sequentially refine network parameters across different realizations. The second pathway employs the decoder of a pretrained generative autoencoder—trained on numerous Gaussian Random Field realizations—to embed random hydraulic conductivity fields. Illustrated through a two-dimensional Darcy flow case study, the method is broadly applicable to a range of parametric PDE problems in hydrology, engineering, and environmental sciences. In particular the model can also be employed to effectively characterize contaminant transport scenarios, in the presence of uncertain model parameters, such as dispersivity or sorption properties. The model can also be employed to represent specific uncertainties related to the contamimant source location or other features affecting the space-time contaminant plume evolution. Results underscore the advantages of staged learning strategies for high-dimensional parametric PDEs, offering an efficient, physics-consistent tool for hydrological modeling and resource management.

This study presents a novel geotechnical engineering approach that utilizes naturally occurring processes to reduce soil permeability in-situ. This approach is inspired by a soil stratification process (Podzolization), where a low permeability layer is formed by metal-organic matter precipitates. In a field experiment, a direct aluminum-organic matter (Al-OM) floc injection was applied to create a continuous vertical flow barrier in a dike. Direct injection uses the shear-dependent size of Al-OM flocs. High-shear conditions (i.e., during injection) lead to the breakage of Al-OM flocs and thus allow their transportation in soils. When the injection stops and low-shear conditions prevail, the Al-OM flocs re-grow in size and block the pores, which ultimately reduces soil permeability. Two different Al-OM floc concentrations were applied in the field. Results show that a continuous flow barrier is only formed at lower concentrations; at higher concentrations a scattered permeability reduction was achieved. This demonstrates the viability of this approach in reducing soil permeability in-situ and shows that the spatial distribution of the flocs depends on input concentration.

A process called EquiAsh® was developed and tested on a large scale. This process aims at upgrading incinerator bottom ash into a long term environmentally safe and stable product. Driven by the agreement between the incinerator branch and the Dutch government in a ‘Green Deal’, the leaching behavior of bottom ash needs improvement. The leaching of metals and salts must be lowered. EquiAsh®, which is a combination of carbonation (accelerated aging), washing and further mineralization, realizes a safe and stable product now and in the future. The bottom ash is in equilibrium with the atmosphere and the pH is stabilized at values around 8.5. Large scale experiments with 1.000–1.300 ton incinerator bottom ash are performed. These experiments give insight into the changes in leaching of metals and salts. In the end, the bottom ash fulfills the Dutch leaching criteria for a freely applicable building material.

By building infrastructure, planners want to exert control over the environment for the sake of society. Due to uncertainty and complexity, such control is always limited and can become contested. Based on a case study of replacing a pumping station, we show how planners can understand the replacement of infrastructure and what informs adequate replacement strategies amid uncertainty. The paper argues that the concepts (un)control and (re)structuring help understand replacements in the context of infrastructure planning. Infrastructure replacements are interventions on different levels which restructure existing systems, asset networks, local areas and assets themselves. Necessary information for developing a replacement strategy, exerted control or uncontrol, possible innovations and restructuring effects differ among these levels. We conclude that planners need to be cognizant that infrastructure replacements, no matter how large or small, restructure both environments and social institutions.

A study was performed based on the design of a new wastewater treatment plant (WWTP) to be built in Weesp, The Netherlands (about 46,000 Population Equivalents (PE)). The conventional activated sludge plant was considered among the alternatives, with and without primary sedimentation. This pre-treatment technique is considered a sustainability measure as it improves the energy balance of the WWTP. However, at the same time, the question arose about the cost effectiveness of this measure. The scope of the study was to assess whether other sustainability measures (like solar panels) can realise the same level of sustainability with lower costs. The outcome of the study indeed shows that, for a new WWTP, it is considerably cheaper to avoid primary sedimentation and focus on other measures like solar panels instead. This appeared not only to be the case for the scale of WWTP Weesp, but also for WWTPs with capacities higher than 500,000 PE. For existing WWTPs with primary sedimentation, the choice can be different as customisation is necessary.

This chapter reviews recent trends and variability in river flows to the North Sea. The main contributors are the River Elbe and the River Rhine. In addition to these large rivers many smaller rivers also discharge into the North Sea. However, by far the biggest contributor is the Baltic Sea outflow. Observation records for the major rivers draining into the North Sea are relatively long, while records for the smaller rivers are typically much shorter. Variability in flow is dependent on variations in weather—mainly precipitation and temperature—from year to year, but also on a wide range of direct and indirect human interventions in the North Sea basin. Rivers draining into the North Sea show considerable interannual and decadal variability in annual discharge. In northern areas this is closely associated with variation in the North Atlantic Oscillation, particularly in winter. Discharge to the North Sea in winter appears to be increasing, but there is little evidence of a widespread trend in summer inflow. Higher winter temperatures appear to have led to higher winter flows, as winter precipitation increasingly falls as rain rather than snow. To date, no significant trends in response to climate change are apparent for most of the individual rivers discharging into the North Sea.

The feasibility of the biodegradation of HCH and its intermediates has been investigated. A recent characterisation of two sites in The Netherlands has shown intrinsic biodegradation of HCH. At one site, breakdown products (monochlorobenzene, benzene and chlorophenol) were found in the core of the HCH-plume, whereas the HCH-concentration decreased over time and space. Characterisation of a second, industrial site indicated less intrinsic biodegradation and the need to stimulate biodegradation. In the laboratory, enhanced HCH degradation was tested with soil and groundwater material from both sites, and the required conversion to the intermediates benzene and monochlorobenzene was demonstrated. Furthermore, the biodegradation of these intermediates could be initiated by adding low amounts of oxygen (<5%). Adding nitrate enhanced this degradation. We hypothesise that this occurs through anaerobic nitrate reducing conversion of oxidised intermediates.At the non-industrial other site, intrinsic degradation took place, as shown in the laboratory experiments. Interpretation of the field data with computer codes Modflow and RT3D was performed. As a result of the modelling study, it has been proposed to monitor natural attenuation for several years before designing the final approach.At the industrial site, the results of the batch experiments are applied. Anaerobic HCH degradation to monochlorobenzene and benzene is stimulated via the addition of an electron donor.Infiltration facilities have been installed at the site to create an anaerobic infiltration zone in which HCH will be degraded, and these facilities are combined with the redevelopment of the site.