Papers by Fredrik Huthoff
Land
Rivers are important ecosystems, vital to the livelihoods of hundreds of millions of humans and o... more Rivers are important ecosystems, vital to the livelihoods of hundreds of millions of humans and other species. Despite their environmental, social, and economic importance, current use of rivers is unsustainable, due to a combination of solid waste and high levels of pollutants. Plastic materials are among the most predominant of such pollutants. Based on the need for additional research in this area, this study examines pressures put to rivers and explores trends related to riverine plastic pollution, with a focus on Asia. Apart from the bibliometric analysis, and relying on the collected information, examples describing the drivers of riverine plastic pollution in a sample of Asian countries are described, outlining the specific problem and its scope. Among some of the results obtained from it, mention can be made to the fact that much of the literature focuses on plastic pollution as a whole and less on one of its most significant ramifications, namely microplastics. Additionally...
Damping of ship-induced primary waves in groyne fields
NCR Days 2021, 2021
Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne... more Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Hydraulic Structures and Flood RiskRivers, Ports, Waterways and Dredging EngineeringEnvironmental Fluid Mechanic
Community-centred Disaster Risk Reduction: Experiences from “Our Flood Mural” in Beira, Mozambique
<p><span>Based on the notion that Flood risk communic... more <p><span>Based on the notion that Flood risk communication contributes to Disaster Risk Reduction (DRR), a novel community-centred approach called “Our Flood Mural”/“Nosso Mural de Cheias” was tested in Beira, Mozambique. “Our Flood Mural” centres around the co-creation of an interactive mural painting that highlights local experiences of past flood events, informs on the existing flood risk in the area and suggests possible risk-reducing measures. The mural brings together local knowledge and arts, and modern information technologies. “Our Flood Mural” can easily be upscaled and adapted to the local context in various settings. </span></p><p><span>A key part of “Our Flood Mural” was active engagement with the local community. Survey results and plenary community sessions were held and showed that the people of the targeted community have a broad understanding of what they can do to reduce flood risk, such as strengthening of rooftops, moving to higher ground, and freeing drainage canals from clutter. These shared experiences were incorporated in the design of the mural which was made by a local artist. Also, two interactive QR-codes were included on the mural to offer additional (online) information: one linking to local weather forecasts and giving background information on the development process of the mural. The location of the mural was mutually decided to be at a local market where it is exposed to a wide audience on a daily basis. </span></p><p><span>During the implementation of the mural, festivities were organized with local leaders present to draw attention to the purpose of the mural. Local leaders, community members, and aid organisations expressed ownership and pride as well as the desire to expand the idea to other locations and to address societal issues other than flood risk. It was also noticeable that the linkage of the mural to online information drew attention in the community, showing the mural’s potential as a means of introducing new technologies and information channels to reach a target audience. </span></p><p><span>Lessons-learned from our community-centred approach include the importance of organizing plenary sessions and carrying out local surveys to assure accurate representation of the communities’ flood risk situation, and to assure adequate use of imagery and/or text. The visibility and accessibility of the different steps in the co-creation approach can help communities, technical experts, aid organizations, and officials interact constructively and identify potential improvements in each other’s actions. </span></p>
Automated quantification of river morphodynamics from satellite imagery for large multithreaded rivers
River Flow 2020, 2020
In recent years, various studies have appeared on (automated) processing of river morphodynamics ... more In recent years, various studies have appeared on (automated) processing of river morphodynamics from satellite images. A key challenge in such approaches is to use appropriate and consistent methods to quantify eroded and deposited areas and channel migration rates. This is particularly important in highly dynamic multi-threaded rivers, where apparent bank lines can move significantly with changing water levels. To assure a consistent treatment of bank lines we use a methodology where channels are identified by detecting the vegetation boundary. We apply this methodology to a 250 km reach of the Ayeyarwady river (Myanmar) and extract metrics for eroded and deposited areas and channel migration. These morphological metrics are compared to hydrologic conditions, and significant correlations were found. It shows that the proposed method may help to classify and better understand river dynamics rivers of large multithreaded rivers.
Estimating equivalent roughness lengths based on wake sizes
Scaling expressions are derived for equivalent roughness lengths to describe average flow over cy... more Scaling expressions are derived for equivalent roughness lengths to describe average flow over cylindrical vegetation and two-dimensional dunes. The derivation is based on the assumption that the spatial extent of a flow separation zone behind a bluff body controls flow resistance. A comparison with experimental data available from literature shows that the scaling relations capture the dominant dependencies of the equivalent roughness length. Also, it is shown that the proposed methodology is consistent with the practice of using an equivalent grain roughness for flow over a rough bed. The derived scaling expressions are useful for engineering applications in large-scale flow situations where it is not feasible to make use of more detailed flowmodeling techniques.
Hydraulic resistance in flow models
We also thank K. Vermeer (HKV Consultants) for reviewing the report. 3 Comparison of NBS cases 19... more We also thank K. Vermeer (HKV Consultants) for reviewing the report. 3 Comparison of NBS cases 19 3.1 Introduction 3.2 Case 1: Belgium-River Kleine Nete 3.3 Case 2: Netherlands-side channels (Room for the River) 3.4 Case 3: Scotland-Eddleston water 3.5 Synthesis: scoring of NBS using the evaluation framework 4 Discussion 26
A 2D morphodynamic river model is applied to evaluate bed level changes after implementation of a... more A 2D morphodynamic river model is applied to evaluate bed level changes after implementation of a flood prevention measure. The bed level changes are calculated in a deterministic simulation using a simplified discharge hydrograph, as well as in a probabilistic approach where a set of variable, more realistic discharge time-series is used. It is demonstrated that variability in the dischargehydrograph has important impacts on the resulting bed levels, and that by using a simplified hydrograph in the deterministic calculation relatively large uncertainties are associated with the morphological outcomes. Recommendations are given to construct an adjusted simplified hydrograph that may yield a better match with probabilistic results, and thereby reducing uncertainties of deterministic morphodynamic calculations. Also, it is shown that morphological effects caused by a flood prevention measure may vary significantly laterally across a river section. This observation reinforces the need ...
Modelling vegetation roughness for river basin management (2003-2007)
Relation between accuracy of floodplain roughness parameterization and uncertainty in 2D hydrodynamic models
Introduction Flood risk has significantly increased over the last four decades, quantified as the... more Introduction Flood risk has significantly increased over the last four decades, quantified as the number of reported occurrences and the number of people affected (CRED, 2010). Hydrodynamic models are used routinely within the framework of disaster risk management to compute flood risk and reduce economic damage and human suffering. They are used to model inundation extent, water depth and flow velocity for flood hazard assessment. While a lot of progress has been made in solving the flow equations efficiently and reliably (Hunter et al., 2007; Bates et al., 2010) uncertainty reduction has remained a major issue. The current study aims at providing better insight into the uncertainty of flood water levels due to uncertain floodplain roughness parameterization. The study focusses on three key elements in the uncertainty of floodplain roughness: (1) classification error of the landcover map, (2), within class variation of vegetation structural characteristics, and (3) mapping scale. M...
The effect of uncertain floodplain roughness in hydrodynamic flood simulations
In the Netherlands, 2D-hydrodynamic simulations are used to evaluate the effect of potential safe... more In the Netherlands, 2D-hydrodynamic simulations are used to evaluate the effect of potential safety measures against river floods. In the investigated scenario's, the floodplains are completely inundated, thus requiring realistic representations of hydraulic roughness of floodplain vegetation. The current study aims at providing better insight into the uncertainty of flood water levels due to uncertain roughness characteristics in the floodplains. The study focusses on three key elements in the uncertainty of floodplain roughness: (i) the uncertainty of ecotope classifications in the floodplains, (ii), the uncertainty that arises from translating ecotopes to floodplain roughness and (iii) the effect of spatial differentiation of ecotope units. To assess the effect of the first error source, new realisations of ecotope maps were made based on the current ecotope map of the Netherlands and an error matrix of the classification. For the second error source, field measurements of ve...
Hydraulic resistance of submerged cylindrical elements: a two-layer scaling approach
Earth Sciences Research Journal, 2005
The hydraulic resistance of vegetation can play a major role in the hydrodynamics of rivers with ... more The hydraulic resistance of vegetation can play a major role in the hydrodynamics of rivers with extensive natural floodplains. Contrary to commonly used wall roughness methods, vegetation penetrates the flow field and thereby causes drag and, subsequently, additional energy losses. In this study, these processes are treated in an idealized form by replacing vegetation with cylindrical elements with homogeneous geometrical
(In 2 Volumes, with CD-ROM), 2004
Towards the realization of appropriate modeling of vegetation roughness for river management purp... more Towards the realization of appropriate modeling of vegetation roughness for river management purposes, a sensitivity analysis was carried out in order to identify the dominant parameters on predicted water levels. Based on 1D theoretical considerations and 1D numerical calculations, hydraulic properties of a simple prismatic channel were examined in relation to changing floodplain roughness, relative floodplain width and the trajectory length of roughened floodplain. It is shown that water level rise is most sensitive to changes in floodplain width if the original floodplain width is comparable in size to the width of the main channel. For changes in the trajectory length of the roughened floodplain, a rough absolute range was identified where sensitivity on resultant water levels is significant.
Theory for flow resistance caused by submerged roughness elements
Journal of Hydraulic Research, 2012
Journal of Flood Risk Management, 2012
Two-dimensional hydrodynamic models are frequently used for flood protection studies to compute i... more Two-dimensional hydrodynamic models are frequently used for flood protection studies to compute inundation patterns and to estimate potential economic damage. However, the modelling of river processes involves numerous uncertainties. Knowledge of the type and magnitude of uncertainties is crucial for a meaningful interpretation of the model outcomes and its usefulness in decision making. The objective of this study was to quantify the uncertainty in the design water levels due to uncertain bed form and vegetation roughness for the Dutch River Waal. We quantified and combined these sources of uncertainty by means of a Monte Carlo simulation. The results showed that the 95% confidence interval of the design water levels is 0.49 m, 0.34 m and 0.12 m for bed form, vegetation classification and vegetation roughness parameterisation, respectively, and approximately 0.68 m for the combined roughness. These uncertainties are significant in view of Dutch river management practice.
Channel roughness in 1D steady uniform flow: Manning or Chézy?
Astronomy & Astrophysics, 2002
High-resolution IRAS maps are used to search for the presence of stellar-wind bow-shocks around h... more High-resolution IRAS maps are used to search for the presence of stellar-wind bow-shocks around high-mass X-ray binaries (HMXBs). Their high space velocities, recently confirmed with Hipparcos observations, combined with their strong stellar winds should result in the formation of wind bow-shocks. Except for the already known bow-shock around Vela X-1 (Kaper et al. 1997), we do not find convincing evidence for a bow-shock around any of the other HMXBs. Also in the case of (supposedly single) OB-runaway stars, only a minority appears to be associated with a bow-shock (Van Buren et al. 1995). We investigate why wind bow-shocks are not detected for the majority of these OB-runaway systems: is this due to the IRAS sensitivity, the system's space velocity, the stellar-wind properties, or the height above the galactic plane? It turns out that none of these suggested causes can explain the low detection rate (∼40%). We propose that the conditions of the interstellar medium mainly determine whether a wind bow-shock is formed or not. In hot, tenuous media (like inside galactic superbubbles) the sound speed is high (∼100 km s −1), such that many runaways move at subsonic velocity through a low-density medium, thus preventing the formation of an observable bow-shock. Superbubbles are expected (and observed) around OB associations, where the OB-runaway stars were once born. Turning the argument around, we use the absence (or presence) of wind bow-shocks around OB runaways to probe the physical conditions of the interstellar medium in the solar neighbourhood.
Water balance in the Dutch river Rhine and rating curve uncertainty
The added value of Nature-Based Solutions
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Papers by Fredrik Huthoff