Nathalie Asselman- Consultant at Deltares
Nathalie Asselman
- Consultant at Deltares
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59
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Introduction
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Publications
Publications (59)
In July of 2021, large areas in the catchment of the Meuse River in Belgium, the Netherlands and Germany were affected by extreme rainfall and floods. In the Netherlands, measured peak discharges in the upstream part of the Meuse and regional tributaries were the highest ever recorded. This resulted in extreme water levels in the upstream reaches,...
De Programmatische Aanpak Grote Wateren (PAGW) beoogt de natuur in en langs de grote wateren in Nederland robuust en toekomstbestendig verder te ontwikkelen. Dit betreft onder andere de Gelderse Poort, als een van vier natuurkernen in het rivierengebied. Hiervoor wordt momenteel een pre-verkenning uitgevoerd, waarvoor een LandschapsEcologische Syst...
Peak attenuation results in a gradual decrease of the peak discharge when a flood propagates in downstream direction. Peak attenuation occurs along all rivers, but is not equally strong on all rivers. The rate of peak attenuation depends on the river geometry, such as river slope, floodplain width and available storage areas (floodplain, wetlands a...
Tijdens de hevige neerslag in België, Duitsland en Nederland is het regenwater snel naar de regionale rivieren en de Maas gestroomd, waarna deze rivieren buiten hun oevers traden. Dit hoofdstuk beschrijft de hydrodynamische feiten (afvoeren, waterstanden, overstroomd gebied), plaatst dit in perspectief door vergelijking met onder meer eerdere hoogw...
Door klimaatverandering verandert het afvoerregime van onze grote rivieren. Hoogwaters worden hoger en frequenter, laagwaters lager en langduriger. Hoe we daarop reageren hangt af van hoe we klimaatverandering zien: als opgave, of als kans om onvolkomenheden aan te pakken. In dit artikel presenteren we aanzetten voor een meer geo-ecologisch gefunde...
There is increasing attention for the robustness of systems, in view of more frequent and more extreme weather events. Calls to increase a system's robustness are usually motivated by the resulting reduced sensitivity to extreme events and uncertainties about their probability of occurrence. The concept has been elaborated for flood risk systems, b...
The Netherlands has just finished implementing the Room for the Rivers program along the Rhine and Meuse Rivers in response to increasing river discharges. Recently, making more room for the river is, however, being challenged for future application because the flood defenses are assessed to be too weak and will need reinforcement anyway. To be abl...
Utrecht University's "Low Land Genesis" borehole descriptions from 1959-1990 have been digitized since the 1990ies, importantly during a 2017 project (DANS KDP scheme) focusing on corings by staff, next to corings by students. Borehole descriptions of younger years were mostly made digital right after collection. The database contains borehole desc...
Het Verhaal is geschreven voor eenieder die werkt aan de inrichting
en het beheer van de Maas. We nemen u mee in het ontstaan,
de ontwikkeling en het functioneren van de Maas, de invloed van
de mens daarop en de vele wensen van de maatschappij die de
Maas - in haar toch al krappe keurslijf - moet accommoderen.
Het Verhaal van de Maas geeft een beel...
Decision Support Systems (DSS’s) have been developed for many years. Their main goal was originally to support decision-makers. Reviews show, however, that the actual use of most DSS’s did fall short of these ambitions. The goal of DSS’s has gradually shifted to enhancing stakeholder engagement for better informed and societally supported decisions...
In this first approximation of the narrative Story of the River (‘Verhaal van de Rivier’) the key messages of the responsible manager of the Rhine and Meuse Rivers (Rijkswaterstaat) is specified in behalf of all actors involved in the policy, governance and management of our large rivers (national authorities, provinces, municipalities, water board...
Describes the application for the Rhine branches in the Netherlands of a method to calculate the cost for reinforcements of dikes taking into account the effects of river widening
Describes a method to calculate the cost for reinforcements of dikes taking into account the effects of river widening.
The Netherlands is updating its flood protection, whilst fully taking into account climate change and socioeconomic development. This translates in ‘anticipatory standards’ which need to be met in 2050, and which apply for the then foreseen climate and economy. Whilst the government maintains to have adopted a policy of adaptive planning and manage...
Since 1996, the Netherlands has adopted a flood risk management policy based on making more room for the rivers. Currently, the focus in flood risk management is being adapted again, in view of increasing societal vulnerability and foreseeable effects of climate change. In this context, the choice between making more room for the river and/or stren...
Flood risk management planning involves making decisions on which measures to implement and when to do so. This is particularly difficult in view of global changes, which are inherently uncertain. Rational decision making on which comprehensive strategy to implement, or on which measures to take first, requires ex-ante assessments that question whe...
Flood risk management planning involves making decisions on which measures to implement, and when to do so. Rational decision making on which comprehensive strategy to implement, or on which measures to take first, requires ex-ante assessments that question whether flood risk is effectively reduced, and against which societal costs. Such decision m...
To obtain a reliable estimate of the effect of combinations of flood-mitigation measures we propose a new method that takes into account the interference between separate measures. We applied this proposed Corrected-Discharge Method (CDM) to a case in which maximum errors in estimated water levels of the River Meuse were reduced by 81% as compared...
Tijdens een studiedag over ‘Dijken voor de toekomst’, die KvK-Thema 1 in november 2011 samen met STOWA had georganiseerd, werd duidelijk dat veel discussie over ‘praktisch doorbraakvrije’ dijken het gevolg is van verschillende percepties, mede veroorzaakt doordat op onderdelen nog kennis ontbreekt.
KvK heeft gevraagd enkele van die openstaande kenn...
Flood inundation models have become essential tools in flood risk management, being used also in the analysis of historical flood events, which is often needed for a reliable assessment of the potential flood hazard. This study aims at reconstructing the 1951 inundation of the Polesine Region, Italy. The 1951 flooding was a mayor natural catastroph...
Uncertainty analyses of flood damage assessments generally require a
large amount of model evaluations. This is often hampered by the high
computational costs necessary to calculate flood extents and depths
using 2-dimensional flow models. In this paper we developed a new
approach to estimate flood inundation depths that can be incorporated in
a Mo...
Uncertainty analyses of flood damage assessments generally require a large amount of model evaluations. This is often hampered by the high computational costs necessary to calculate flood extents and depths using 2-dimensional flow models. In this paper we developed a new approach to estimate flood inundation depths that can be incorporated in a Mo...
Uncertainty analyses of flood damage assessments generally require a large amount of model evaluations. This is often hampered by the high computational costs necessary to calculate flood extents and depths using 2-dimensional flow models. In this paper we developed a new approach to estimate flood inundation depths that can be incorporated in a Mo...
River and coastal floodplains are often protected by vast systems of connected embankments. In the Netherlands, about 55% of the country is protected in this way, by some 3600 km of primary defences. The protection level is probably the highest in the world, and annual mean flood risks are low. Nevertheless, the consequences of a major flood event...
Resistance to flow was studied in a 6–7-m deep straight tidal channel of the Westerschelde estuary. For this purpose long-term current velocity and water level measurements were carried out at three locations. Vertical current and sand concentration profiles were also measured. Bed morphology was characterized by 0.2–0.4-m high dunes which showed c...
As little is known about the effectiveness of floods of different magnitude on floodplain sedimentation, the aim of this study was to determine the effective discharge for overbank sedimentation in The Netherlands. The study was carried out on a grass-covered, embanked, floodplain section along the River Waal, the main distributary of the River Rhi...
Na de ramp van 1953 pleitte de Deltacommissie voor compartimentering van Centraal-Holland. Het geadviseerde beschermingsniveau van 1:10.000 ging daar zelfs van uit. Van de compartimentering is echter niets terecht gekomen en het principe is enigszins in de vergetelheid geraakt. Rond deze tijd komen de resultaten van een recente studie beschikbaar r...
In het kader van de beleidsvoorbereiding Waterveiligheid 21e eeuw (WV21) vindt een herbezinning plaats op de beheersing van overstromingsrisico’s in Nederland. Daarbij gaat het zowel om het verminderen van de kans op overstromingen (waterkeren) als het beperken van de gevolgen van overstromingen. Voor het bepalen van de
maatschappelijk meest gewens...
Over the past decennia, the palaeogeographic development of the Rhine-Meuse delta in the Netherlands has been extensively
studied and an extremely detailed database of the Holocene delta architecture has been established. The delta offers a unique
palaeo-environment to study both palaeogeography and avulsions on a timescale of millenia, because of...
Large parts of the Netherlands lie below sea-level, and the hazard of large-scale floods leading to extensive damage and loss
of life is always present. Existing methods to estimate potential numbers of casualties are based on limited empirical data
and do not account for evacuation. In this paper a framework for the estimation of loss of life caus...
In dit rapport is voor het eerst getracht op een systematische wijze de vraag te beantwoorden hoe bestendig Nederland is tegen klimaatverandering – en tegen de daarmee gepaard gaande zeespiegelstijging. Daarbij zijn de recent gepubliceerde klimaatscenario’s van het KNMI voor 2050 gebruikt, alsmede vier sociaal-economische scenario’s met een zichtti...
Denitrification, plant uptake and sedimentation are important mechanisms of nutrient retention in floodplains. Due to nutrient retention, nitrogen (N) and phosphorus (P) loads of the river decrease, which is a primary aim in European water quality management. However, the relative contribution of the various retention mechanisms to nutrient retenti...
The objective of this study was to estimate the potential effects of changes in climate and land use on the mobilization of fine sediment and the net transport of wash load from the upstream basin to the lower Rhine delta. For this purpose, a suite of geographical information system-embedded models was developed that simulates the production, and t...
Over the past decade, concern about the morphological and ecological condition of the rivers Rhine and Meuse has increased. Simultaneously with the projects for rehabilitation, measures were proposed to improve the discharge capacity of the high-water floodway, in order to reduce the risk of river flooding. Although many studies focus on the impact...
In discussies over Ruimte voor Rivieren wordt vaak gesteld dat de mens nog tot zeer onlangs veel ruimte aan de rivier heeft onttrokken, door onder meer dijken op te hogen of bij dijkverzwaring dichter bij de rivier te leggen. Een kwantitatief beeld van hoeveeI ruimte dat heeft gekost bestaat echter niet, soms leidend tot 'welles-nietes' discussies...
Airborne laser altimetry is a promising new technique for rapid and detailed mapping of land surface topography and vegetation cover. The availability of laser scan data is expected to yield a great improvement in mapping and quantification of hydraulic roughness, which is needed for two-dimensional modelling of overbank flow. In this study, hydrau...
In discussies over Ruimte voor Rivieren wordt vaak gesteld dat de mens nog tot zeer
onlangs veel ruimte aan de rivier heeft onttrokken, door onder meer dijken bij dijkverzwaring dichter bij de rivier te leggen en door buitendijkse terreinen hoogwatervrij op te hogen. Een kwantitatief beeld van hoeveel ruimte dat wel niet betreft bestaat echter niet...
A large part of the sediment in lowland rivers is transported as wash load. As wash load is a non-capacity load it often is modelled using empirical relations, such as the rating curve technique. Sediment rating curves in the form of a power function are derived for several locations along the river Rhine and its main tributaries, using different f...
This paper is part of the special publication No.163, Floodplains: interdisciplinary approaches (eds S.B. Marriott and J.Alexander). Over the past century, many rivers throughout Europe have been channelized. The channel of the River Rhine in the Netherlands was straightened, groynes were built, and minor river dykes were constructed to prevent inu...
The behaviour of suspended sediment in rivers is often a function of energy conditions, i.e. sediment is stored at low flow and transported under high discharge conditions. The timing of maximum sediment transport can, however, also be related to mixing and routing of water and sediment from different sources. In this study suspended sediment trans...
The importance of floods of different magnitude on floodplain sedimentation can be estimated from sedimentation measurements carried out during a series of floods. However, because these measurements represent sediment accumulation during the entire flood, they cannot be used to estimate the importance of individual flood stages on sediment deposit...
It is often believed that extreme but infrequent events are most important in the development of landforms. When evaluating the overall effect of large floods on floodplain sedimentation, quantitative measurements of both high- and low-magnitude events should be considered. To analyse the role of flood magnitude on floodplain sedimentation, we meas...
This article addresses spatial variability of comtemporary floodplain sedimentation at the event scale. Measurements of overbank deposition were carried out using sediment traps on 11 floodplain sections along the rivers Waal and Meuse in The Netherlands during the high-magnitude flood of December 1993. During the flood, sand sheets were locally de...
Erosion, transport and deposition of fine suspended sediments are both directly and indirectly influenced by climate conditions. In this study, the suspended sediment transport regime of the river Rhine under present and future climate conditions was assessed. The impact of climate change on the sediment transport regime was investigated using sedi...
This paper presents the result of measurements of floodplain sedimentation using sediment traps. The study was carried out on two embanked floodplains along the Rivers Rhine and Meuse in The Netherlands during a 3 day flood in January 1993. Raster maps of sediment accumulation were made by interpolating the measurements from the traps using block k...
