Hoek Van Holland Research Articles

Probabilistic characterizations of flood hazards in deltas: Application to Hoek van Holland (Netherlands)

Coastal flooding events pose a critical risk in delta areas, since they are characterized by population growth and urban expansion. A better understanding of Extreme Water Levels (EWLs), the mechanisms generating them, and their components, i.e., astronomical tide and storm surge is of great importance as they drive the maintenance and design of flood protection systems. Therefore, a statistical investigation of them can provide new insights for more reliable flood risk mitigation infrastructures. In this study, we analyse these components and compare different probabilistic methods i.e., univariate extreme value analysis, copula functions, and Joint Probability Method (JPM) for the better estimation of EWLs. We use Hoek van Holland (NL) as a representative case study, since the dynamic conditions of this deltaic environment with man-made infrastructures render the area of strategic importance. The results indicate that a more accurate estimate of the declustering time between extreme events can be achieved using correlation of high surges and high wind speeds, taking into consideration also the wind direction. In the Southwest Delta this time estimated to be around 4 days. Furthermore, the EWLs components, i.e., surge and astronomical tide, show negative dependence. From the comparison between statistical approaches to model EWLs, results show that EWLs estimated via EVA and JPM do not vary significantly, while copulas’ seems to outperform the other methods. However, the selection of the proper copula to show the dependence is critical. As a conclusion, the analysis of the dependence between tides and storm surges can lead to more robust inferences of EWLs.

How should storm surge barrier maintenance strategies be changed in light of sea-level rise? A case study

Sea-level rise and changes in storminess, together with population growth and coastward migration, are increasing the risks of coastal flooding. The impacts are amplified in coastal cities due to the high concentration of inhabitants, infrastructure and services in low lying areas. Many coastal cities are located in estuaries, and storm surge barriers are often constructed to provide flood protection in these areas with long exposed coastlines. For these complex and unique structures, maintenance is vital to ensure they remain reliable and comply with legal protection standards. To ensure safe conditions for workers, storm surge barriers typically define water level thresholds, at which maintenance work must stop when these water levels are reached or exceeded. This paper evaluates the changes in past and future water levels exceeding the maintenance threshold to inform management, maintenance and operation strategies, and design, of storm surge barriers. The Maeslant barrier in Rotterdam, Netherlands is used as a case study to test this analysis. Water levels from measurements taken at the Hoek van Holland tide gauge are compared to the maintenance threshold level. The number of past threshold exceedances is determined and the sensitivity of exceedances to threshold level are assessed. Results show that the maintenance threshold has been exceeded 991 times of which 13% occurred during the maintenance season. Conversely, there were periods in the storm season when water levels were below the maintenance threshold and work could have been carried out safely. The effect of sea-level rise and natural inter-annual tidal cycles on future threshold exceedances is also assessed. Findings reveal that the maintenance window will shift earlier in the year and narrow until exceedances of the maintenance threshold occur regularly all year around. With 1 m sea-level rise maintenance threshold exceedances are likely to occur regularly all year around by 2048. This analysis highlights that maintenance strategies at the Maeslant barrier will need to be adapted for the barrier to remain operational until its design life of 2 100. This is due to the increase in maintenance threshold exceedances resulting from natural interannual tidal cycles combined with sea-level rise. This analysis framework is applicable to existing barriers worldwide to assess future intervention points and for barriers in the design phase to verify the implications of design decisions on planned maintenance.

Een getekende kaart van De Beer

A drawn map of the island De Beer A century ago nature reserve De Beer was situated opposite Hoek van Holland. The young (and later famous) Niko Tinbergen wrote a book in 1930 about this ‘bird island’. His younger friend Jan Joost ter Pelkwijk made a kind of mental map of De Beer in 1932 with more than 80 sketches on it. This map is compared with the 1938 topographical map.

Communicating Climate Change to a Local but Diverse Audience: On the Positive Impact of Locality Framing

ABSTRACT This study investigates the impact of locality framing in infographics about sea level rise as a consequence of anthropogenic climate change (ACC). Our experiment sampled solely inhabitants of Hoek van Holland (HvH), a coastal town in the Netherlands for which future sea level rise is a pertinent issue. We analyzed the participants’ attitudes towards ACC mitigating behaviors, and found that an infographic with a local, HvH oriented frame had a higher positive impact on attitudinal change than an infographic with a more general, global frame. To account for demographic variation between participant samples in previous studies on locality framing, whose findings were inconsistent, we also tested if the observed effect of locality framing was moderated by gender, age, education level, income, political background, and religiosity. This was not the case. Our findings advocate for the application of local frames in ACC communication, irrespective of the target population’s demographic characteristics.

Large-scale changes of the semidiurnal tide along North Atlantic coasts from 1846 to 2018

Abstract. We investigated the long-term changes of the principal tidal component M2 along North Atlantic coasts, from 1846 to 2018. We analysed 18 tide gauges with time series starting no later than 1940. The longest is Brest with 165 years of observations. We carefully processed the data, particularly to remove the 18.6-year nodal modulation. We found that M2 variations are consistent at all the stations in the North-East Atlantic (Cuxhaven, Delfzijl, Hoek van Holland, Newlyn, Brest), whereas some discrepancies appear in the North-West Atlantic. The changes started long before the 20th century and are not linear. The secular trends in M2 amplitude vary from one station to another; most of them are positive, up to 2.5 mm/yr at Wilmington since 1910. Since 1990, the trends switch from positive to negative values in the North-East Atlantic. Concerning the possible causes of the observed changes, the similarity between the North Atlantic Oscillation and M2 variations in the North-East Atlantic suggests a possible influence of the large-scale atmospheric circulation on the tide. Our statistical analysis confirms large correlations at all the stations in the North-East Atlantic. We discuss a possible underlying mechanism. A different spatial distribution of mean sea level (corresponding to water depth) from one year to another, depending on the low-frequency sea-level pressure patterns, could impact the propagation of the tide in the North Atlantic basin. However, the hypothesis is at present unproven.

Storm Surge and Extreme River Discharge: A Compound Event Analysis Using Ensemble Impact Modeling

Abstract. Many winter deep low-pressure systems passing over Western Europe have the potential to induce significant storm surge levels along the coast of the North Sea. The accompanying frontal systems lead to large rainfall amounts, which can result in river discharges exceeding critical thresholds. The risk of disruptive societal impact increases strongly if river runoff and storm-surge peak occur near-simultaneously. For the Rhine catchment and the Dutch coastal area, existing studies suggest that no such relation is present at time lags shorter than six days. Here we re-investigate the possibility of finding near-simultaneous storm surge and extreme river discharge using an extended data set derived from a storm surge model (WAQUA/DCSMv5) and two hydrological river-discharge models (SPHY and HBV96) forced with conditions from a high-resolution (0.11°/12 km) regional climate model (RACMO2) in ensemble mode (16 × 50 years). We find that the probability for finding a co-occurrence of extreme river discharge at Lobith and storm surge conditions at Hoek van Holland are up to four times higher (than random chance) for a broad range of time lags (−2 to 10 days, depending on exact threshold). This highlights that the hazard of a co-occurrence of high river discharge and coastal water levels cannot be neglected in a robust risk assessment.

Natural weathering severity of typical coastal environment on polystyrene: Experiment and modeling

Natural weathering of polystyrene (PS) was performed at six exposure sites with various climate types along the coastal line from China to Europe, including Qionghai (typical hot-humid climate), Sansha (island hot-humid climate), Chennai (savanna hot-humid climate), Jeddah (xerothermic climate), Sanary-sur-Mer (mediterranean climate), Hoek van Holland (warm-temperate climate). The chemical structure, morphology and color changes of PS after weathering were characterized by FTIR, DSC, SEM and Color spectrometer, and relative weathering severity of different climates on PS were compared. Results show that Sansha has the highest severity value while the severity value of Hoek van Holland is the lowest. The degradation degree of PS at the sites of Qionghai, Sansha, and Chennai is higher than that at other sites, resulted in a deterioration of the optical properties and serious damage of the sample surface. In the xerothermic climate, the optical properties of PS decrease drastically during the process of natural weathering, while only slight change in hydroxyl index and carbonyl index is observed, and micrographic surface does not differ from the surface of un-weathered materials. For other climates, the degradation degree was low, resulting in a relative slow change of optical properties and long time for the appearance of surface defects. In order to quantify the relative severity of these climates, a mathematic model was proposed based on the basic degradation principle of polymer materials, which could predict the failure time of PS. The failure time was predicted by the model using gloss loss of PS as failure index, with an accuracy up to 99.2%.

The Unwelcome Crows

This article focuses on a small population of house crows in the town of Hoek van Holland in the Netherlands, likely descendants of two birds that arrived by ship in the mid-1990s. In 2014, after twenty years of peaceful co-existence, the government began the process of eradicating this population. Just across the water from Hoek van Holland is the Port of Rotterdam – Europe’s largest port – and an “engine” for the global patterns of production, trade and consumption that are today remaking our world, ushering in what many are calling “the Anthropocene.” Focusing on these crows and this port – in a way that is attuned to the broader placetimes that constitute our present – this paper explores the possibilities and limitations of hospitality as a basis for crafting shared worlds in difficult times.

The co-incidence of storm surges and extreme discharges within the Rhine–Meuse Delta

The Netherlands is a low-lying coastal area and therefore threatened by both extreme river discharges from the Meuse and Rhine rivers and storm surges along the North Sea coastline. To date, in most flood risk analyses these two hazardous phenomena are considered independent. However, if there were a dependence between high sea water levels and extreme discharges this might result in higher design water levels, which might consequently have implications for flood protection policy in the Netherlands. In this study we explore the relation between high sea water levels at Hoek van Holland and high river discharges at Lobith. Different from previous studies, we use physical models forced by the same atmospheric forcing leading to concomitant and consistent time series of storm surge conditions and river discharge. These time series were generated for present day conditions as well as future climate projections and analysed for dependence within the upper tails of their distribution. In this study, dependence between the discharge at Lobith and storm surge at Hoek van Holland was found, and the dependence was highest for a lag of six days between the two processes. As no significant dependence of the threats was found for cases without time lag, there is no need for considering dependence in flood protection and policy making. Although future climate change is expected to lead to more extreme conditions in river discharges, we cannot conclude from this study that it will change the magnitude of the dependence for extreme conditions.

Anaerobic bioleaching of metals from waste activated sludge

Heavy metal contamination of anaerobically digested waste activated sludge hampers its reuse as fertilizer or soil conditioner. Conventional methods to leach metals require aeration or the addition of leaching agents. This paper investigates whether metals can be leached from waste activated sludge during the first, acidifying stage of two-stage anaerobic digestion without the supply of leaching agents. These leaching experiments were done with waste activated sludge from the Hoek van Holland municipal wastewater treatment plant (The Netherlands), which contained 342μgg−1 of copper, 487μgg−1 of lead, 793μgg−1 of zinc, 27μgg−1 of nickel and 2.3μgg−1 of cadmium. During the anaerobic acidification of 3gdry weightL−1 waste activated sludge, 80–85% of the copper, 66–69% of the lead, 87% of the zinc, 94–99% of the nickel and 73–83% of the cadmium were leached. The first stage of two-stage anaerobic digestion can thus be optimized as an anaerobic bioleaching process and produce a treated sludge (i.e., digestate) that meets the land-use standards in The Netherlands for copper, zinc, nickel and cadmium, but not for lead.

AN IDEALIZED METEOROLOGICAL-HYDRODYNAMIC MODEL FOR EXPLORING EXTREME STORM SURGE STATISTICS IN THE NORTH SEA

This paper explores an alternative method to determine extreme surge levels at the Dutch Coast. For this exploration, specific focus is on the extreme water level at Hoek van Holland, The Netherlands. The alternative method has been based on a joint probability model of the storm characteristics at the North Sea. The intent of this method is to provide a better physical and statistical insight into the effects of meteorological characteristics on surge levels and surge duration, especially for surges of more extreme storms currently not captured in existing water level measurement records. The meteorological part is an analytical parametrical model based on the Holland model for hurricanes, which results in time- and space-varying wind and pressure fields of North Sea storms. The wind and pressure forcing is then applied in the hydrodynamic model which numerically solves the nonlinear depth-averaged shallow water equations in a one-dimensional domain from the edge of the continental shelf between Scotland and Norway to Hoek van Holland. Validation against wind observations from historical storms at one location in the entire domain shows good results. Results of the calibrated surge level model are reasonable if peak surge levels are considered. The surge duration, however, is underestimated by the model. Next, the model has been applied to define extreme surge levels using Monte Carlo Analysis. Probability density distributions for the storm parameters based on historical data have been used as input. The computed surge level (including tide) with a statistical return period of 10,000 years appears to be close to the value from statistical extrapolation of surge levels. The output also indicates that the average duration of computed surges with a return period of 10,000 year is roughly two hours longer than the storm duration currently adopted.

Measurements of air pollution emission factors for marine transportation in SECA

Abstract. The chemical composition of the plumes of seagoing ships was measured during a two week long measurement campaign in the port of Rotterdam, Hoek van Holland The Netherlands, in September 2009. Altogether, 497 ships were monitored and a statistical evaluation of emission factors (g kg−1 fuel) was provided. The concerned main atmospheric components were SO2, NO2, NOx and the aerosol particle number. In addition, the elemental and water-soluble ionic composition of the emitted particulate matter was determined. Emission factors were expressed as a function of ship type, power and crankshaft rotational speed. The average SO2 emission factor was found to be roughly half of what is allowed in sulphur emission control areas (16 vs. 30 g kg−1 fuel), and exceedances of this limit were rarely registered. A significant linear relationship was observed between the SO2 and particle number emission factors. The intercept of the regression line, 4.8 × 1015 (kg fuel)−1, gives the average number of particles formed during the burning of 1 kg zero sulphur content fuel, while the slope, 2 × 1018, provides the average number of particles formed with 1 kg sulphur burnt with the fuel. Water-soluble ionic composition analysis of the aerosol samples from the plumes showed that ~144 g of particulate sulphate was emitted from 1 kg sulphur burnt with the fuel. The mass median diameter of sulphate particles estimated from the measurements was ~42 nm.

Bias correction in extreme value statistics with index around zero

Applying extreme value statistics in meteorology and environmental science requires accurate estimators on extreme value indices that can be around zero. Without having prior knowledge on the sign of the extreme value indices, the probability weighted moment (PWM) estimator is a favorable candidate. As most other estimators on the extreme value index, the PWM estimator bears an asymptotic bias. In this paper, we develop a bias correction procedure for the PWM estimator. Moreover, we provide bias-corrected PWM estimators for high quantiles and, when the extreme value index is negative, the endpoint of a distribution. The choice of k, the number of high order statistics used for estimation, is crucial in applications. The asymptotically unbiased PWM estimators allows the choice of higher level k, which results in a lower asymptotic variance. Moreover, since the bias-corrected PWM estimators can be applied for a wider range of k compared to the original PWM estimator, one gets more flexibility in choosing k for finite sample applications. All advantages become apparent in simulations and an environmental application on estimating “once per 10,000 years” still water level at Hoek van Holland, The Netherlands.

Impact of a shift in mean on the sea level rise: Application to the tide gauges in the Southern Netherlands

The rates of sea level rise during 1940–2002 estimated in the Southern Netherlands at tide gauges of Vlissingen, IJmuiden, Maassluis and Hoek van Holland vary from 1.7 to 2.7 mm/yr despite a relatively small distance ( < 140 km ) between these stations. We have supposed that the observed inconsistency between the sea level trends could be due to an abrupt shift in the mean level of the tidal records provoked by some natural or anthropogenic processes. A shift detector based on the decomposition of the observations in empirical orthogonal functions and on the generalized likelihood ratio statistic has been constructed to evaluate the probability of the presence of a shift in the observed tidal records. A rapid change of mean of 25 mm at Hoek van Holland during the 1972–1973 period and of 17 mm at Vlissingen between 1973 and 1976 have been found to be statistically significant. The estimates of the sea level rise after correcting for shifts in the Vlissingen and Hoek van Holland tidal records are highly coherent and range between 1.9 and 2.1 mm/yr.

A Midlatitude Precipitating Cloud Database Validated with Satellite Observations

Abstract The simulations of five midlatitude precipitating events by the nonhydrostatic mesoscale model Méso-NH are analyzed. These cases cover contrasted precipitation situations from 30° to 60°N, which are typical of midlatitudes. They include a frontal case with light precipitation over the Rhine River area (10 February 2000), a long-lasting precipitation event at Hoek van Holland, Netherlands (19 September 2001), a moderate rain case over the Elbe (12 August 2002), an intense rain case over Algiers (10 November 2001), and the “millennium storm” in the United Kingdom (30 October 2000). The physically consistent hydrometeor and thermodynamic outputs are used to generate a database for cloud and precipitation retrievals. The hydrometeor vertical profiles that were generated vary mostly with the 0°C isotherm, located between 1 and 3 km in height depending on the case. The characteristics of this midlatitude database are complementary to the GPROF database, which mostly concentrates on tropical situations. The realism of the simulations is evaluated against satellite observations by comparing synthetic brightness temperatures (BTs) with Advanced Microwave Sounding Unit (AMSU), Special Sensor Microwave Imager (SSM/I), and Meteosat observations. The good reproduction of the BT distributions by the model is exploited by calculating categorical scores for verification purposes. The comparison with 3-hourly Meteosat observations demonstrates the ability of the model to forecast the time evolution of the cloud cover, the latter being better predicted for the stratiform cases than for others. The comparison with AMSU-B measurements shows the skill of the model to predict rainfall at the correct location.

Effluent treatment by multi-media filtration, microfiltration and ultrafiltration: results of a pilot investigation at WWTP Hoek van Holland

Upgrading of wastewater treatment plant (WWTP) effluent as a part of the Dutch governmental policy to close the water cycle has increasing interest now. The Water Board Hoogheemraadschap van Delfland together with the project team of Witteveen + Bos Consulting Engineers, Delft University of Technology and Rossmark water treatment investigated the reuse possibilities of WWTP effluent in the region of Delfland. Therefore pilot research was carried out at WWTP Hoek van Holland applying different filtration techniques: multi-media filtration, micro- and ultrafiltration. The results show stable process performances of the different filtration techniques when proper pre-treatment was applied. For microfiltration the filtration characteristics were strongly influenced by particles which were not retained in the multi-media filter. For ultrafiltration the filtration characteristics were strongly influenced by organic components < 0.2 microm. The upgraded WWTP effluent could not be used directly as process water or for agriculture purposes, due to high concentrations of COD and salts in the WWTP effluent and filtrates. However WWTP effluent or floc filtrate could be applied directly as water for the washing of sea-sand.

On the behaviour of tidal current directions due to the presence of submarine sand waves

Abstract Side-scan sonar records reveal that the crestlines of megaripples in the troughs as well as on both sides of the slopes of sand waves form an angle with the crestline of the sand waves itself. The existence of such an angle between the crestline of megaripples and sand waves indicates that changes of the (tidal) current direction across sand waves can be expected. Direct evidence that such (tidal) current direction changes occur above sand waves is derived from measurements of the Air–Sea Interaction Drift Buoy (ASIB) system at the sea surface and from side-scan sonar records of the sea bed. Both systems were operated from on board research vessels during two C-STAR field experiments in the Hoek van Holland study area off the Dutch coast in April 1996 and in April 1997. Measurements performed by electrical resistance wires on board the ASIB system indicate that variations of the short and moderate wave direction and the wave directional spread are associated with changes of the (tidal) current direction at the sea surface. According to the results of the measurements derived from the ASIB system and the side-scan sonar records it can be summarised that the variation of the direction of short and moderate period water waves as well as changes of the (tidal) current speed and direction across large sand waves must be considered for correct modelling of the wave-current interaction mechanism.

Analysis of wind speed observations on the North Sea coast

Abstract As part of the objective to describe the wind climate of the North Sea and the coastal zone, specifically with regard to wind energy applications, we study the observations of two meteorological stations on the North Sea coast: Hoek van Holland (HVH) and IJmuiden (IJM). Statistical analysis of the 8-year datasets shows that the mean wind speeds are 7.8 m/s (at 18.5 m height) for IJM, and 7.6 m/s (at 15.0 m height) for HVH, respectively. The coastal observations are compared to the observations of three offshore platforms in the North Sea analysed in earlier work. It is found that diurnal variations are very similar in autumn and winter, but differ in spring and summer. Furthermore, wind speeds with fetch over sea do behave very similar at the coastal stations and offshore platforms. It is shown that the effects of thermal circulation leading to the sea breeze are distinctly present, at least up to 30 km offshore. These effects can be attributed to relatively low wind speeds (less than 7 m/s at 10 m height), and manifest themselves as a shift, on average, of wind directions from easterly to westerly directions during the day. Higher wind speeds (more than 7 m/s), most relevant for wind energy applications, compare well at coastal stations and offshore platforms.

A three-dimensional finite difference model for computation of near- and far-field transport of suspended matter near a river mouth

A three-dimensional model for the dispersion of suspended sediment after a point release of dredged material in a stratified area of the coastal sea is described. To obtain good near-bottom resolution a vertical coordinate transformation is applied. A finite difference method, which is non-negative and accurate for concentration clouds smaller than the grid mesh size, is used for the computation of the dispersion of fine sediment. The model is applied to a part of the Dutch coastal zone. Transport paths of suspended sediment are computed, revealing a strong residual eddy north of Hoek van Holland, the main outlet of Rhine river water.

Forecasting meteorological effects on water levels on a routine basis with a numerical model

In this article the suitability of a numerical model for forecasting the meteorological effects on water levels at the five main Dutch gauge-stations is investigated. Mean values and standard deviations of differences between observed and forcast meteorological effects during high-and low-tide for diffierent forecast periods were determined for the period 1 October 1977 to 1 April 1978, and compared with persistience, i.e.a previously observed set-up. Since the skill of the model highly depends on its behaviour under extreme conditions, a selection was made of those cases with a considerable meteorological effect (12 dm or more at Vlissngen, Hoek van Holland and Den Helder, 15 dm or more at Harlingen and Delfzijl), and this selection was studied as well. Examining the persistence, it turned out that the observed meteorological effect is also influenced by inaccuracies in the tidal values. The skill of the model appeared to be satisfiactory, especially when used as a warning system 12 to 24 hours in advance.