Martin Verlaan

Martin Verlaan
Delft University of Technology | TU · Department of Applied Mathematics

PhD

About

100
Publications
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2,779
Citations

Publications

Publications (100)
Article
Full-text available
The first objective of this paper is to assess by means of geodetic network analyses the impact of adding model-based hydrodynamic leveling data to the Unified European Leveling Network (UELN) data on the precision and reliability of the European Vertical Reference Frame (EVRF). In doing so, we used variance information from the latest UELN adjustm...
Article
Full-text available
Seasonal modulation of the M2 tide has been quantified for the entire Arctic Ocean and connected regional seas, using tidal harmonic analysis of water levels derived from Synthetic Aperture Radar altimetry. Results are compared to numerical simulations that model the effect of two limiting cases of seasonal landfast ice cover on the M2 tide. The la...
Poster
Full-text available
Monitoring of the intertidal and subtidal bathymetry at large spatiotemporal scales using traditional surveying methods is a challenging and costly task. Well established methods of remote sensing and increasing frequency of freely available satellite data enable automated monitoring of intertidal and subtidal bathymetry. A number of methods exist...
Article
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The world’s coastal areas are increasingly at risk of coastal flooding due to sea-level rise (SLR). We present a novel global dataset of extreme sea levels, the Coastal Dataset for the Evaluation of Climate Impact (CoDEC), which can be used to accurately map the impact of climate change on coastal regions around the world. The third generation Glob...
Article
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Rainfall estimates based on satellite data are subject to errors in the position of the rainfall events in addition to errors in their intensity. This is especially true for localized rainfall events such as the convective rainstorms that occur during the monsoon season in sub-Saharan Africa. Many satellite-based estimates use gauge information for...
Article
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We assess the suitability of ECMWF Integrated Forecasting System (IFS) data for the global modeling of tropical cyclone (TC) storm surges. We extract meteorological forcing from the IFS at a 0.225° horizontal resolution for eight historical TCs and simulate the corresponding surges using the global tide and surge model. Maximum surge heights for Hu...
Article
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The western North-Atlantic coast experienced major coastal floods in recent years. Coastal floods are primarily composed of tides and storm surges due to tropical (TCs) and extra-tropical cyclones (ETCs). We present a reanalysis from 1988 to 2015 of extreme sea levels that explicitly include TCs for the western North-Atlantic coastline. Validation...
Article
This article explores the use of the ensemble Kalman filter technique to improve the accuracy of North Sea wave field analyses. A nonhydrostatic convective-permitting mesoscale model was used to provide high-resolution forcing winds. These were adjusted by assimilating measurements of offshore wave heights directly into the wave model state. The en...
Article
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Global warming is expected to drive increasing extreme sea levels (ESLs) and flood risk along the world’s coastlines. In this work we present probabilistic projections of ESLs for the present century taking into consideration changes in mean sea level, tides, wind-waves, and storm surges. Between the year 2000 and 2100 we project a very likely incr...
Article
This article explores the use of the ensemble Kalman filter technique to improve the accuracy of North Sea wave field analyses. A nonhydrostatic convective-permitting mesoscale model was used to provide high-resolution forcing winds. These were adjusted by assimilating measurements of offshore wave heights directly into the wave model state. The en...
Article
We present an efficient and flexible alternative method to connect islands and offshore tide gauges with the height system on land. The method uses a regional, high-resolution hydrodynamic model that provides total water levels. From the model, we obtain the differences in mean water level (MWL) between tide gauges at the mainland and at the island...
Article
Full-text available
The article Effects of self-attraction and loading at a regional scale: a test case for the Northwest European Shelf, written by Maialen Irazoqui Apecechea, Martin Verlaan, Firmijn Zijl, Camille Le Coz and Herman Kernkamp, was originally published Online First without open access.
Article
Full-text available
For the numerical discretization schemes, the violation of the enstrophy conservation causes a systematic and unrealistic energy cascade towards the high wave numbers. The same also holds for the data assimilation scheme where the total energy, enstrophy and divergence could be strongly affected by the data assimilation settings. The same occurs to...
Article
Water-related disasters, such as fluvial floods and cyclonic storm surges, are a major concern in the world's mega-delta regions. Furthermore, the simultaneous occurrence of extreme discharges from rivers and storm surges could exacerbate flood risk, compared to when they occur separately. Hence, it is of great importance to assess the compound ris...
Conference Paper
Full-text available
The physics of extreme high-water during coastal storms covers a wide range of scales, from tides and storms propagating over long distances to the shape of local bays, reefs and islands all contributing to what is potentially extreme high-water. Traditionally, modelling of storm-surges is mostly performed at a regional scale, sometimes extended wi...
Poster
Full-text available
Floods are the most frequent of natural disasters, affecting millions of people across the globe every year. To manage flood related risks, preparedness by means of flood forecasting and early warning services is one of the principal strategies. For many at-risk areas, however, the availability of such services is still lacking. Here, flood forecas...
Article
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The impact of the self-attraction and loading effect (SAL) in a regional 2D barotropic tidal model has been assessed, a term with acknowledged and well-understood importance for global models but omitted for boundary-forced, regional models, for which the implementation of SAL is non-trivial due to its non-local nature. In order to understand the i...
Article
Full-text available
Future extreme sea levels (ESLs) and flood risk along European coasts will be strongly impacted by global warming. Yet, comprehensive projections of ESL that include mean sea level (MSL), tides, waves, and storm surges do not exist. Here, we show changes in all components of ESLs until 2100 in view of climate change. We find that by the end of this...
Article
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Estimating the current risk of coastal flooding requires adequate information on extreme sea levels. For over a decade, the only global data available was the DINAS-COAST Extreme Sea Levels (DCESL) dataset, which applies a static approximation to estimate extreme sea levels. Recently, a dynamically derived dataset was developed: the Global Tide and...
Article
Full-text available
Monitoring stations have been used for decades to properly measure hydrological variables and better predict floods. To this end, methods to incorporate these observations into mathematical water models have also been developed. Besides, in recent years, the continued technological advances, in combination with the growing inclusion of citizens in...
Article
Full-text available
Tides are a key component in coastal extreme water levels. Possible changes in the tides caused by mean sea-level rise (SLR) are therefore of importance in the analysis of coastal flooding, as well as many other applications. We investigate the effect of future SLR on the tides globally using a fully global forward tidal model: OTISmpi. Statistical...
Conference Paper
Full-text available
The primary offshore data used in regional quasi-geoid modelling are sea surface heights from satellite radar altimetry and gravity anomalies from marine gravimeters. Overall, the radar altimeter data have a better coverage and a higher spatial resolution compared to shipboard gravity data. Vice versa, shipboard gravity data have a better quality c...
Conference Paper
Full-text available
Traditionally, islands have been connected to the mainland height system using hydrostatic levelling. This highly specialized measurement technique is very expensive and time consuming, which is the reason why most countries in the world decided to abandon this technique. In the Netherlands, hydrostatic levelling was abandoned more than 30 years ag...
Article
Full-text available
Nature Communications 7 : Article number: 11969 10.1038/ncomms11969 ( 2016 ); Published: 27 June 2016 ; Updated: 8 September 2016 In Fig. 4 of this Article, the y axes in panels ‘b–e’ are incorrect. The correct version of Fig. 4 appears below as Fig.
Article
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Extreme sea levels, caused by storm surges and high tides, can have devastating societal impacts. To effectively protect our coasts, global information on coastal flooding is needed. Here we present the first global reanalysis of storm surges and extreme sea levels (GTSR data set) based on hydrodynamic modelling. GTSR covers the entire world's coas...
Data
Supplementary Figures 1-10, Supplementary Notes 1-2 and Supplementary References.
Article
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Data assimilation methods provide a means to handle the modeling errors and uncertainties in sophisticated ocean models. In this study, we have created an OpenDA-NEMO framework unlocking the data assimilation tools available in OpenDA for use with NEMO models. This includes data assimilation methods, automatic parallelization, and a recently implem...
Article
Full-text available
This paper presents a simple method for estimating the impact of assimilating individual or group of observations on forecast accuracy improvement. This method is derived from the nsemble-based observation impact analysis method of Liu and Kalnay (Q J R Meteorol Soc 134:1327–1335, 2008). The method described here is different in two ways from their...
Article
Full-text available
One of the primary observational datasets of sea level is represented by the tide gauge record. We propose a new method to estimate variability on decadal time scales from tide gauge data by using a state space formulation, which couples the direct observations to a predefined state space model by using a Kalman filter. The model consists of a time...
Conference Paper
Full-text available
Scientific and end-user collaboration on operational flood risk modelling and forecasting requires an environment where scientists and end-users can physically work together and demonstrate, enhance and learn about new tools, methods and models for forecasting and warning purposes. Therefore, Deltares has built a real-time demonstration, training a...
Article
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For the Netherlands, accurate water level forecasting in the coastal region is crucial, since large areas of the land lie below sea level. During storm surges, detailed and timely water level forecasts provided by an operational storm surge forecasting system are necessary to support, for example, the decision to close the movable storm surge barri...
Article
Full-text available
Monitoring stations have been used for decades to properly measure hydrological variables and better predict floods. To this end, methods to incorporate such observations into mathematical water models have also being developed, including data assimilation. Besides, in recent years, the continued technological improvement has stimulated the spread...
Article
Full-text available
Monitoring stations have been used for decades to properly measure hydrological variables and better predict floods. To this end, methods to incorporate such observations into mathematical water models have also being developed, including data assimilation. Besides, in recent years, the continued technological improvement has stimulated the spread...
Conference Paper
Full-text available
Title: Autolocalization techniques for ocean modelling using OpenDA Presenter: Nils van Velzen Author(s): Nils van Velzen (TU-Delft/VORtech) Umer Altaf (TU-Delft) Martin Verlaan (TU-Delft/Deltares) Preference for Oral or Poster: Oral Data assimilation method provide a mean to handle the modelling errors and uncertainties in sophisticated ocean...
Conference Paper
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At EGU 2015, the eWaterCycle project (www.ewatercycle.org) will launch an operational high-resolution Hydrological global model, including 14 day ensemble forecasts. Within the eWaterCycle project we aim to use standards and open source software as much as possible. This ensures the sustainability of the software created, and the ability to swap ou...
Conference Paper
This paper describes the plans for a new information system to supply nowcasts and forecasts of current information for navigation to the Port of Rotterdam. The system will consist of both HF radar and a 3D hydrodynamic model. The currents measured by the HF radar will be assimilated into the 3D model to provide the best forecast.
Article
Full-text available
A 3D hydrodynamic model (Delf3D) was applied for San Quintin Bay (SQB), B.C., Mexico. Calibration and validation were conducted using measured bathymetry, wind, water surface elevation and velocities fields. The calibration period took place during the winter of 2010. Model predictions were evaluated graphically and statistically against field obse...
Article
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This paper considers the incorporation of constraints to enforce physically based conservation laws in the ensemble Kalman filter. In particular, constraints are used to ensure that the ensemble members and the ensemble mean conserve mass and remain nonnegative through measurement updates. In certain situations filtering algorithms such as the ense...
Article
Full-text available
In real-time operational coastal forecasting systems for the northwest European shelf, the representation accuracy of tide–surge models commonly suffers from insufficiently accurate tidal representation, especially in shallow near-shore areas with complex bathymetry and geometry. Therefore, in conventional operational systems, the surge component f...
Article
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Water level reduction with global navigation satellite systems in bathymetric surveying requires knowledge of the ellipsoidal heights of lowest astronomical tide (LAT). The traditional approach uses tidal water levels of an ocean tide model, which are subtracted from mean sea level (MSL). This approach has two major drawbacks: the modeled water lev...
Article
Current and new applications of 2D storm surge models such as the Dutch Continental Shelf Model (DCSM) require that the models provide proper estimates of the instantaneous water levels expressed relative to a particular geoid, rather than only the tide and surge components expressed relative to the ill-defined model’s zero height surface. For DCSM...
Technical Report
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In WP9 the evaluation of existing and future coastal observational platforms will be performed by applying Observational System Experiments (OSEs) and Observational System Simulation Experiments (OSSEs) that use data assimilation systems based on high resolution coastal ocean models. Data assimilation systems cover a wide range of European coastal...
Article
Full-text available
ENSURF (Ensemble SURge Forecast) is a multi-model application for sea level forecast that makes use of several storm surge or circulation models and near-real time tide gauge data in the region, with the following main goals: 1. providing easy access to existing forecasts, as well as to its performance and model validation, by means of an adequate...
Article
The adjoint method can be used to identify uncertain parameters in large-scale shallow water flow models. This requires the implementation of the adjoint model, which is a large programming effort. The work presented here is inverse modeling based on model reduction using proper orthogonal decomposition (POD). An ensemble of forward model simulatio...
Article
Data Assimilation techniques are essential elements in state-of-the-art development of models and their use in operational forecasting and real-time control in the fields of groundwater, surface water and soil systems. In meteorological and atmospheric sciences, steady improvements in numerical weather forecasting and climate prediction over the la...
Article
Full-text available
The Dutch continental shelf model (DCSM) is a shallow sea model of entire continental shelf which is used operationally in the Netherlands to forecast the storm surges in the North Sea. The forecasts are necessary to support the decision of the timely closure of the moveable storm surge barriers to protect the land. In this study, an automated mode...
Article
Full-text available
ENSURF (Ensemble SURge Forecast) is a multi-model application for sea level forecast that makes use of existing storm surge or circulation models today operational in Europe, as well as near-real time tide gauge data in the region, with the following main goals: – providing an easy access to existing forecasts, as well as to its performance and m...
Article
Peak storm water levels are examined along the northern Dutch coast, and the impact of closing a surge barrier near the mouth of the River Ems is quantified. The Ems Barrier, located in northwest Germany near Emden, was put into operation in 2002. Previous modeling studies indicate that closing the Ems Barrier results in higher highwater levels sea...
Conference Paper
Full-text available
The creation of reference surfaces has primarily been a national activity in the North Sea countries. A national approach prevents the creation of consistent common references, which are desperately needed for international data distribution in the coastal zone, GNSS-based bathymetric surveying, and the development of hydrodynamic models, on the sc...
Article
The adjoint method is usually used to identify uncertain parameters in large-scale shallow water flow models. This requires the implementation of the adjoint model, which is huge programming effort. The work presented in this paper is based on stochastic simultaneous perturbation of all model parameters to generate a search direction and avoids the...