Deltares
  • Delft, Netherlands
Recent publications
Study Region Forty-one river basins in Brazil and neighboring countries in South America. Study Focus In large river basins, on countrywide or continental scales, it is often difficult to have consistent and accurate long time series of spatially distributed precipitation data available. However, these are needed to calibrate hydrological models and to run hydrological simulations continuously in real-time streamflow forecasting. In this study, we assess two real-time precipitation products based on rain gauges and satellite data (TRMM-MERGE and CPC-NOAA) for their use in streamflow forecasting in the hydropower sector in Brazil. To take advantage of each precipitation data source and derive a unique dataset, a methodology is proposed to combine, extend, and validate the datasets. We consider the discharges at the river basin outlets as an independent and robust reference for hydrological applications. Observed discharges are used to quantify precipitation uncertainties and to weight the blending, while discharges obtained from hydrological modeling are used to validate the final precipitation product. New Hydrological Insights for the Region The proposed blending method, which uses the uncertainty of the original datasets to define the weighting factors, was efficient in generating a precipitation product that performs better than each dataset separately when used to force a hydrological model. The use of the double-mass curve correlation to extend the time series of the datasets beyond their common period allowed us to produce long time series of precipitation for South American basins and hydrological applications. The study shows that it is possible to rely on river discharge data and hydrological modeling to select and combine different precipitation products in the region and presents a step-by-step methodology to do so.
The SANISAND constitutive model has been widely employed for the simulation of sands cyclic behavior. The shear modulus constant (G0) in SANISAND should be theoretically estimated from maximum shear modulus of soil (Gmax). To estimate G0, however, majority of calibration studies have used triaxial tests data in the shear strain levels larger than those associated with Gmax. This technical note aims to demonstrate how the selection criteria for G0 parameter affects the SANISAND model predictions, particularly in terms of G-reduction (shear modulus -shear strain) curve of sands. First, experimental G-reduction curves for four sands are compared with SANISAND predictions based on the values of G0 parameter estimated from triaxial tests. Then, a new calibration set of SANISAND for a single sand is proposed based on the G0 value estimated from Gmax, obtained from resonant column tests. The results confirm that the numerical shear stiffness values fall significantly lower than the experimental values in small strain ranges when the G0 constant is estimated from triaxial tests. However, the G0 constant estimated from Gmax appropriately predicts the experimental G-reduction curve of the sand in a wide shear strain range.
Background: The first evidence of micro- and nanoplastic (MNP) exposure in the human placenta is emerging. However, the toxicokinetics and toxicity of MNPs in the placenta, specifically environmentally relevant particles, remain unclear. Objectives: We examined the transport, uptake, and toxicity of pristine and experimentally weathered MNPs in nonsyncytialized and syncytialized BeWo b30 choriocarcinoma cells. Methods: We performed untargeted chemical characterization of pristine and weathered MNPs using liquid chromatography high-resolution mass spectrometry to evaluate compositional differences following particle weathering. We investigated cellular internalization of pristine and weathered polystyrene (PS; 0.05-10μm) and high-density polyethylene (HDPE; 0-80μm) particles using high-resolution confocal imaging and three-dimensional rendering. We investigated the influence of particle coating with human plasma on the cellular transport of PS particles using a transwell setup and examined the influence of acute MNP exposure on cell viability, damage to the plasma membrane, and expression of genes involved in steroidogenesis. Results: Chemical characterization of MNPs showed a significantly higher number of unique features in pristine particles in comparison with weathered particles. Size-dependent placental uptake of pristine and weathered MNPs was observed in both placental cell types after 24 h exposure. Cellular transport was limited and size-dependent and was not influenced by particle coating with human plasma. None of the MNPs affected cell viability. Damage to the plasma membrane was observed only for 0.05μm PS particles in the nonsyncytialized cells at the highest concentration tested (100μg/mL). Modest down-regulation of hsd17b1 was observed in syncytialized cells exposed to pristine MNPs. Discussion: Our results suggest that pristine and weathered MNPs are internalized and translocated in placental cells in vitro. Effects on gene expression observed upon pristine PS and HDPE particle exposure warrant further examination. More in-depth investigations are needed to better understand the potential health risks of MNP and chemicals associated with them under environmentally relevant exposure scenarios. https://doi.org/10.1289/EHP10873.
Previous studies have demonstrated that tides are subject to considerable changes on secular time scales. However, these studies rely on sea level observations from tide gauges that are predominantly located in coastal and shelf regions and therefore, the large‐scale patterns remain uncertain. Now, for the first time, satellite radar altimetry (TOPEX/Poseidon & Jason series) has been used to study worldwide linear trends in tidal harmonic constants of four major tides (M2, S2, O1, and K1). This study demonstrates both the potential and challenges of using satellite data for the quantification of such long‐term changes. Two alternative methods were implemented. In the first method, tidal harmonic constants were estimated for consecutive 4‐year periods, from which the linear change was then estimated. In the second method, the estimation of linear trends in the tidal constants of the four tides was integrated in the harmonic analysis. First, both methods were assessed by application to tide gauge data that were sub‐sampled to the sampling scheme of the satellites. Thereafter the methods were applied to the real satellite data. Results show both statistically significant decreases and increases in amplitude up to 1 mm/year and significant phase changes up to ∼0.1 deg/year. The level of agreement between altimeter‐derived trends and estimates from tide gauge data differs per region and per tide.
The demand for a more conscious and integrating design process within the field of urban infrastructure development is based in the fact that the environmental crisis can only be dealt with by increasing the resilience of the built environment. Civil engineering and spatial design are fields with very different cultures and languages, yet interdisciplinary cooperation between these fields, as well as among sub-disciplines within each, is at the base of urban infrastructure development. Delft University of Technology (TUD) incorporated interdisciplinary design into its MSc-level education of students in the faculties of civil engineering and architecture focusing on reconstruction projects after crises. Via surveys of the participating students, the effectiveness of the interdisciplinary design methods used, and the interpretation of the terms multidisciplinary and interdisciplinary are revealed. From survey results about Multidisciplinary and Interdisciplinary understanding it can be concluded that “multidisciplinary” is considered a group process and not an outcome, and mainly communication skills are important. “Interdisciplinary” is considered the outcome and intertwining of knowledge and products. Interdisciplinary design is the integration of sectoral responsibilities, goals and solutions. Interdisciplinary design should entail a conscious and orchestrated process in which the disciplines present their ideas within a shared value system before systematic integration. The challenges are on a personal and cognitive level, an open attitude is necessary to be able to perceive and react, process and understand, retrieve information and make decisions and produce appropriate responses for co-creation. This can be done by training and learning the value of this open attitude and the acknowledgement of the necessity and added quality of the re-integration of engineering within the spatial design process.
The erosion threshold, beyond which bed sediments start to move, is a key parameter describing sediment transport processes. For silt‐dominated mixtures, in which the grain size is between sand and clay, existing experimental studies exhibit contradictory observations. That is, the erosion was either sand‐like or clay‐like, suggesting transitional erosion behavior. To explore the underlying mechanism of the transitional erosion behavior of silt‐sized sediment, we revisited the topic of the erosion threshold of sand‐silt mixtures by carrying out a series of erosion experiments for different bed compositions. The results suggest that there exists a critical silt content of approximately 35%, separating two domains. Below this critical value, the critical bed shear stress follows the Shields criterion, whereas above this value, the erosion threshold of a mixed bed increases abruptly and remains relatively constant with a further increase in silt content. By combining with existing data, we found that the proposed critical silt content acts as a tipping point, beyond which the mixed bed shifts from a sand‐dominated to a silt‐dominated domain. For the silt‐dominated domain, a stable silt skeleton can be formed by attraction forces that resist erosion. However, the attraction forces are too weak to form a stable silt skeleton when the silt content is too small. Based on this finding, a modified critical bed shear stress formula is proposed for silt‐dominated mixtures, which results in a better agreement with experimental data (an averaged bias of 10%), performing better than existing formulas (larger than 30%).
Natural environments such as coastal wetlands, lowland river floodplains, and deltas are formed by sediment, transported by watercourses and the sea, and deposited over century to millennium timescales. These dynamic environments host vulnerable ecosystems with an essential role for biodiversity conservation, coastal protection and human activities. The body of these landforms consists of unconsolidated sediments with high porosity and compressibility. Consequently, they often experience significant compaction due to their own weight, that is, autocompaction, which creates an important feedback within the geomorphological evolution of the landform. However, this process is generally oversimplified in morphological simulators. We present a novel finite element (FE) simulator that quantifies the impact of natural compaction on landform evolution in a three‐dimensional setting. The model couples a groundwater flow and a compaction module that interact in a time‐evolving domain following landform aggradation. The model input consists of sedimentation varying in time, space and sediment type. A Lagrangian approach underlies the model by means of an adaptive mesh. The number of FEs gradually increases to accommodate newly deposited sediments and each FE changes its shape, that is, becomes compressed, following sediment compaction. We showcase the model capabilities by simulating three long‐term depositional processes at different spatial scales: (a) vertical growth of a tidal marsh, (b) infilling of an oxbow lake, and (c) progradation of a delta lobe. Our simulations show that compaction is the primary process governing the elevation and geomorphological evolution of these landforms. This highlights that autocompaction is an important process that determines the resilience of these low‐lying landforms to climate change.
The use of geogrids to anchor Sheet Pile Walls (SPW) is relatively new. A series of small-scale tests was performed to investigate the behaviour of geogrid-anchored SPWs subjected to strip footing surcharge loading. Particle Image Velocimetry (PIV) techniques were used to measure soil displacement and analyse the global failure mechanism and dominant soil-geogrid interaction mechanisms. One of the tests was duplicated in a test box that was eight times as wide, showing that the influence of the small width of the test box was acceptably small. A 2D finite element model (PLAXIS) was used to simulate the tests and there was a reasonable match with the test results. The position of the strip footing load, and the length and number of the geogrid anchors, proved to be key factors in determining the bearing capacity. The results provide new insights into the stabilising effect and the effective length of the geogrid anchors, in other words the length along which geogrid-soil friction is mobilised. Contrary to the Dutch design guidelines for reinforced soil walls and conventionally anchored sheet pile walls, the results showed that the geogrid provides resistance in the active zone under the strip footing surcharge loading.
Long-term exploration of the Groningen gas field in the Netherlands led to induced seismicity. Over the past nine years, an increasingly sophisticated Ground Motion Model (GMM) has been developed to assess the site response and the related seismic hazard. The GMM output strongly depends on the shear-wave velocity (V S), among other input parameters. To date, V S model data from soil profiles (Kruiver et al., Bulletin of Earthquake Engineering, 15(9): 3555-3580, 2017; Netherlands Journal of Geosciences, 96(5): s215-s233, 2017) have been used in the GMM. Recently, new V S profiles above the Groningen gas field were constructed using ambient noise surface wave tomography. These so-called field V S data, even though spatially limited, provide an independent source of V S to check whether the level of spatial variability in the GMM is sufficient. Here, we compared amplification factors (AF) for two sites (Borgsweer and Loppersum) calculated with the model V S and the field V S (Chmiel et al., Geophysical Journal International, 218(3), 1781-1795, 2019 and new data). Our AF results over periods relevant for seismic risk (0.01-1.0 s) show that model and field V S profiles agree within the uncertainty range generally accepted in geo-engineering. In addition, we compared modelled spectral accelerations using either field V S or model V S in Loppersum to the recordings of an earthquake that occurred during the monitoring period (M L 3.4 Zeerijp on 8 January 2018). The modelled spectral accelerations at the surface for both field V S and model V S are coherent with the earthquake data for the resonance periods representative of most buildings in Groningen (T = 0.2 and 0.3 s). These results confirm that the currently used V S model in the GMM captures spatial variability in the site response and represents reliable input for the site response calculations.
Edge-of-field mitigations (EoFM) can reduce agricultural nutrient losses to surface water. To determine the feasibility and cost-effectiveness of EoFM, we developed a spatial–economic modelling approach and applied it in the Waituna Lagoon Catchment (Southland, New Zealand) to evaluate reductions in nitrogen (N) and phosphorus (P) loads, utilising three EoFMs: constructed wetlands, woodchip bioreactors and aluminised zeolite filters. Cost-effectiveness per targeted nutrient was calculated using a strategy that considers nutrient reduction potential and implementation costs of EoFM across all farms (catchment-collective approach), and a strategy requiring each farm to mitigate individually using their most cost-effective EoFM mitigations (farm-based approach). Our modelling showed that the load received from potentially EoFM eligible sub-catchments is 46% and 27% for overall N and overall P load, respectively. EoFM can achieve substantial reductions using a catchment-collective approach (max. 24% overall N load; max. 15% overall P load), but cannot on their own provide the reductions required to achieve the desired outcome (59% overall N and 53% overall P load). Catchment-collective approaches for EoFM placement become more cost effective than farm-based approaches when larger nutrient reductions are required (N >33%; P >30%; N&P combined load >16%, based on the received load from potentially EoFM eligible subcatchments).
Small and medium-sized reservoirs play an important role in water systems that need to cope with climate variability and various other man-made and natural challenges. Although reservoirs and dams are criticized for their negative social and environmental impacts by reducing natural flow variability and obstructing river connections, they are also recognized as important for social and economic development and climate change adaptation. Multiple studies map large dams and analyze the dynamics of water stored in the reservoirs behind these dams, but very few studies focus on small and medium-sized reservoirs on a global scale. In this research, we use multi-annual multi-sensor satellite data, combined with cloud analytics, to monitor the state of small (10–100 ha) to medium-sized (> 100 ha, excluding 479 large ones) artificial water reservoirs globally for the first time. These reservoirs are of crucial importance to the well-being of many societies, but regular monitoring records of their water dynamics are mostly missing. We combine the results of multiple studies to identify 71,208 small to medium-sized reservoirs, followed by reconstructing surface water area changes from satellite data using a novel method introduced in this study. The dataset is validated using 768 daily in-situ water level and storage measurements (r2 > 0.7 for 67% of the reservoirs used for the validation) demonstrating that the surface water area dynamics can be used as a proxy for water storage dynamics in many cases. Our analysis shows that for small reservoirs, the inter-annual and intra-annual variability is much higher than for medium-sized reservoirs worldwide. This implies that the communities reliant on small reservoirs are more vulnerable to climate extremes, both short-term (within seasons) and longer-term (across seasons). Our findings show that the long-term inter-annual and intra-annual changes in these reservoirs are not equally distributed geographically. Through several cases, we demonstrate that this technology can help monitor water scarcity conditions and emerging food insecurity, and facilitate transboundary cooperation. It has the potential to provide operational information on conditions in ungauged or upstream riparian countries that do not share such data with neighboring countries. This may help to create a more level playing field in water resource information globally.
An 11 hours survey was performed on the 17th of September 2014 in the Rhine Region Of Freshwater Influence (Rhine-ROFI) about 10 km downstream of the mouth of the Rotterdam Waterway during calm weather conditions. Suspended Particle Matter (SPM) measurements were performed during a full tidal cycle, near the seabed, at neap tide, and samples were taken at 0.6 meter above bed for on-board analysis. The measurements were performed with (a) LISST 100X, a submersible particle size analyzer, (b) LISST-HOLO, a submersible digital holographic camera, (c) a home-made underwater camera and (d) an on-board LabSFLOC2 video microscopy equipment that used in-situ collected samples. The first aim of the present study was to compare the results obtained from the different monitoring techniques and to characterize the different types of suspended particles found in-situ. It was found that that the highly anisotropic particles present in the water column lead to multiple peaks in the Particle Size Distributions (PSD) found using the LISST 100X. Using the LISST-HOLO, underwater camera and LabSFLOC2 camera these particles could properly be imaged and meaningful PSD’s were obtained using these techniques in the size range > 20 μ m. LabSFLOC2, LISST-HOLO and the underwater camera moreover provide information on the size and aspect ratio of particles. On the other hand, LISST 100X can be used to detect the fine fraction (<20 μ m), a size range that is not accessible for the other techniques. From the analysis of the data on the survey day, three classes of particles were identified, based on composition rather than size (the sizes given here are purely indicative): (1) mineral (inorganic) sediment particles in the range size 5 - 20 μ m, (2) organic/inorganic aggregates in the size range 20 - 200 μ m and (3) organic particles in the size range > 200 μ m. A large range of settling velocities (0.1 - 10 mm/s) and aspect ratios between 1 and 10 were recorded by video microscopy (LabSFLOC2). This spreading in settling velocities and aspect ratio was due to the different properties (shape, effective density and size) of the particles in the water column. The second aim of the study was to reproduce the flocs found in-situ in the lab and investigate the kinetics of flocculation between inorganic and living organic matter. Laboratory experiments were conducted with grab samples obtained from Port of Rotterdam harbour and living microalgae ( Skeletonema costatum ). The results of these experiments showed a shift in effective density upon addition of living algae to the sediment, which confirmed the flocculation ability between sediment and microalgae. The flocculation occured on a timescale of minutes and lead to flocs having a large spread in density for a given size, due to the heteregeous inorganic/organic composition of the flocs. This spread in density was at the origin of the large range of settling velocities for a given floc size observed in-situ, which leads to conclude that organic matter should be an important input parameter in sediment transport models.
Purpose This paper presents a regionally downscaled economic model developed to assess the impacts of the management of dredged sediments on Gross Domestic Product (GDP) and jobs created; the model is validated and applied using real project data from sediment management projects in Ireland and Scotland. The model provides significant insight into and allows impact analysis for the economic aspect of sediment management projects with the potential to facilitate and inform stakeholders across the sediment management sector. Methods The economic model facilitates regional analysis of the impacts of sediment management projects on GDP and job creation for direct, indirect and induced effects. Methods for estimating the economic induced impacts are based on industry-specific type I and type II economic multipliers and coefficients, derived for the EU Interreg SURICATES partner countries (Ireland, Scotland, France and the Netherlands) using symmetric input–output tables and application of the open Leontief model and based on available economic data for the identified countries. The model is applied to sediment management projects in Ireland (a harbour development project at Castletownbere) and in Scotland (a bioremediation project at Falkirk). Model results are compared to project data for direct contribution to GDP and direct jobs created, and the model also estimates the indirect and induced economic project impacts. The model has been applied to undertake sensitivity analyses and compare different sediment management options. Results Model results provide a satisfactory comparison to real project data for direct cost and jobs created. Indirect economic benefits for GDP and employment created were estimated from 47 to 53% of direct impacts . The model has been applied to undertake sensitivity analyses and assess a range of different site-specific sediment management options with indirect economic impacts ranging from 42 to 53% of direct impacts. Conclusions The economic model results are compared to real project economic data, the validation exercise proving satisfactory with promising results. Sensitivity analyses and site-specific sediment management options have been assessed. The positive economic impacts of the Castletownbere Harbour project in particular are evident. These results highlight the potentially different economic impacts of the implementation of different sediment management options and in different regions and countries. The model allows the quantification of the economic benefits of sediment management projects. The model provides significant insight into and allows impact analysis for the economic aspect of sediment management projects and has the potential to facilitate and inform stakeholders and decision-makers across the sector.
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484 members
Jos Brils
  • Unit Soil and Subsurface
Ap van Dongeren
  • Department of Marine and Coastal Systems
Jos P M Vink
  • Soil & groundwater systems - sediment and surface water quality group
Albrecht Weerts
  • Inland Water Systems Division
Ghada Y. El Serafy
  • Hydrodynamic and Environmental Systems
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Delft, Netherlands
Website
https://www.deltares.nl/en/