Avulsion in action: Reconstruction and modelling sedimentation pace and upstream flood water levels following a Medieval tidal-river diversion catastrophe (Biesbosch, The Netherlands, 1421–1750AD)

Geomorphology ◽  
2010 ◽  
Vol 118 (1-2) ◽  
pp. 65-79 ◽  
Author(s):  
Maarten G. Kleinhans ◽  
Henk J.T. Weerts ◽  
Kim M. Cohen
2021 ◽  
Author(s):  
Michel Schreinemachers ◽  
Wiebe Strick

<p>Should a bridge always be functional and accessible? Should it always fulfil its purpose? This seemingly self- evident question is a key question in footbridge design that is oriented towards creating experiences.</p><p>Footbridges are able to successfully enriches our experience of a certain context or landscape, it cannot be functional all the time, under all environmental conditions, weather and seasons. A good example is the Zalige bridge designed as part of the Room for the River, a large-scale national program for inland flood- protection in the Netherlands. Build upon the floodplains within a newly created river-park by the city of Nijmegen, the Zalige bridge’s curved shape stands in direct relationship to the fluctuating water levels of the river. When water levels rise, the bridge partially submerges, becoming only accessible through steppingstones. At peak heights, the bridge disappears completely, becoming a metaphor for our relationship to the water.</p><p>“Building a bridge that fails to fulfil its sole purpose of containing the water; this can only be pulled off in the Netherlands.” – jury Dutch Design Awards about the Zalige bridge.</p><p>The loss of functionality is directly related to the creation of an experience. When the water levels rose in January 2018, the bridge became the prime location to experience the changing landscape. It shows that engineering a bridge is not solely focussed on the most efficient engineering, but for the purpose it fulfils as for society. For most pedestrian bridges where the perception of the user is on a different level as for a highway bridge, functionality provides more than just cost driven or efficiency driven parameters. It is more related to the added value for the community. When design not solemnly derives from the sheer taste and predilection of the designer but is based on the user’s experience, it generates a durable relation with a feeling of ownership of its users. The key is to create this experience in an elegant and natural way and not forced or dictated. It should be people's own unique discovery and should not be imposed.</p>


Author(s):  
P. Pekarova ◽  
P. Miklanek ◽  
J. Pekar
Keyword(s):  


2021 ◽  
Vol 152 (A4) ◽  
Author(s):  
G J Macfarlane ◽  
M R Renilson ◽  
T Turner

The safety of a ship which is damaged below the waterline will depend on the way water floods into the internal compartments. The water will cause the ship to take on an angle of heel and trim which will further affect the flooding into the compartments. The ship’s equilibrium position in calm water can be predicted using hydrostatic theory, however at present it is difficult to predict the transient behaviour between the initial upright position of the ship and its final equilibrium. In some cases, the transient motion may cause a capsize prior to a possible equilibrium position being reached. This paper describes an investigation of this phenomenon using a model of a warship with simplified, typical internal geometry. With the model initially stationary, a rapid damage event was generated, and the global motions measured, along with the water levels in some of the internal compartments, as functions of time. Immediately after the damage occurred the model rolled to starboard (towards the damage). It then rolled to port (away from the damage) before eventually returning to starboard and settling at its equilibrium value. In all the tests conducted the equilibrium heel angle was less than that reached during the initial roll to starboard. This implies that the roll damping, and the way in which the water floods into the model immediately following the damage, could both have a very important influence on the likelihood of survival.


2020 ◽  
Author(s):  
Marjolein H.J. van Huijgevoort ◽  
Janine A. de Wit ◽  
Ruud P. Bartholomeus

&lt;p&gt;Extreme dry conditions occurred over the summer of 2018 in the Netherlands. This severe drought event led to very low groundwater &amp;#160;and surface water levels. These impacted several sectors like navigation, agriculture, nature and drinking water supply. Especially in the Pleistocene uplands of the Netherlands, the low groundwater levels had a large impact on crop yields and biodiversity in nature areas. Projections show that droughts with this severity will occur more often in the future due to changes in climate. To mitigate the impact of these drought events, water management needs to be altered.&lt;/p&gt;&lt;p&gt;In this study, we evaluated the 2018 drought event in the sandy regions of the Netherlands and studied which measures could be most effective to mitigate drought impact. We have included meteorological, soil moisture and hydrological drought and the propagation of the drought through these types. Droughts were determined with standardized indices (e.g. Standardized Precipitation Index) and the variable threshold level method. Investigated measures were, for example, higher water levels in ditches, reduced irrigation from groundwater, and increased water conservation in winter. We also studied the timing of these measures to determine the potential for mitigating effects during a drought versus the effectiveness of long term adaptation. The measures were simulated with the agro-hydrological Soil&amp;#8211;Water&amp;#8211;Atmosphere&amp;#8211;Plant (SWAP) model for several areas across the Netherlands for both agricultural fields and nature sites.&lt;/p&gt;&lt;p&gt;As expected, decreasing irrigation from groundwater reduced the severity of the hydrological drought in the region. Severity of the soil moisture drought also decreased in fields that were never irrigated due to the effects of capillary rise from the groundwater, but, as expected, increased in currently irrigated fields. Increasing the level of a weir in ditches had a relatively small effect on the hydrological drought, provided water was available to sustain higher water levels. This measure is, therefore, better suited as a long term change than as ad hoc measure during a drought. The effectiveness of the measures depended on the characteristics of the regions; for some regions small changes led to increases in groundwater levels for several months, whereas in other regions effects were lost after a few weeks. This study gives insight into the most effective measures to mitigate drought impacts in low-lying sandy regions like the Netherlands.&lt;/p&gt;


2014 ◽  
Vol 6 (2) ◽  
pp. 386-399 ◽  
Author(s):  
Liu Liu ◽  
Zongxue Xu

Water resources in the Taihu basin, China, are not only facing the effects of a changing climate but also consequences of an intensive urbanization process with the abandonment of rural activities and the resulting changes in land use/land-cover. In the present work, the impact of climate change and urbanization on hydrological processes was assessed using an integrated modeling system, coupling the distributed hydrological model variable infiltration capacity and the hydraulic model ISIS, while future climate scenarios were projected using the regional climate model providing regional climate for impact studies. Results show a significant increasing trend of impervious surface area, while other types of land cover exhibit decreasing trends in 2021–2050. Furthermore, mean annual runoff under different future climate scenarios will increase, especially during flood seasons, consistent with the changes in precipitation and evapotranspiration for both spatial and temporal distribution. Maximum and mean flood water levels under two future scenarios will be higher than levels under the baseline scenario (1961–1990), and the return periods of storms resulting in the same flood water level will decrease significantly in comparison to the baseline scenario, implying more frequent occurrence of extreme floods in future. These results are significant to future flood control efforts and waterlog drainage planning in the Taihu basin.


Author(s):  
Alexandra Muscalus ◽  
Kevin Haas

Bird/Long Island is a dredge-spoil island located between the north and south channels near the inlet of the Savannah River at the border of Georgia and South Carolina. The island is in a tidally dominant environment and contains cultural and natural resources, including remnants of a Civil War era artillery battery. As a wetland mitigation bank, it is particularly important to the state of Georgia. However, these resources are under threat from documented and ongoing sea level rise, shoreline change (i.e., erosion and accretion) from natural and anthropogenic causes, and land subsidence. In addition to substantial tidal and freshwater flows, the island is subject to locally-generated wind waves primarily from northeast winds, as well as wake from the large container ships transiting to and from the Port of Savannah. A previous study examined the effects of wind and vessel-generated waves on shoreline retreat for the Fort Pulaski National Monument on nearby Cockspur Island (Houser, 2010). The study concluded that while the vessel-generated waves account for nearly 25% of the energy, the wind waves during storm events with increased water levels accounted for the majority of the marsh retreat. Although the proximity of this previous study site to Bird/Long Island is relevant, the different orientations of the islands and the narrowing of the channel create a different hydrodynamic environment. The present work uses field data to characterize the hydrodynamic processes affecting Bird/Long Island, which will improve modeling of its shoreline change.


Author(s):  
Jan Kuper

The life-history and behaviour of the chironomid Metriocnemus (Inermipupa) carmencitabertarum was studied for three years and a comparison was made between two populations in the Netherlands. Key life-history characteristics are reported, including the number of generations (2-5 generations) and duration of larval development (19-55 days). Life-history characteristics differed between the two populations and between generations within a population. These differences were likely related to differences in competitors (mainly Chironomus riparius Meigen) and thermal characteristics of the habitat from variations in water volume and ambient temperature. Results suggested a diapause in summer, when water levels dropped, and not in winter. A clear seasonal pattern in body size was found with pupal length increasing steeply at the beginning of the summer. The increase in body size was positively correlated with mean ambient temperature during larval development. This correlation is in contrast with the Temperature-Size Rule (TSR) in ectotherms, which postulates a negative correlation between temperature and adult body size. The chance of ectotherm predators being present in the habitat is low, which may explain this feature. Life history characteristics supported a recent northward range expansionfor M. (I.) carmencitabertarum due to warmer winters. If correct, it is predicted that the species will be found in Scotland and northern Germany and/or southern Denmark in the near future.


2011 ◽  
Vol 1 (5) ◽  
pp. 34
Author(s):  
J. B. Schijf

The North Sea is a shallow sea and therefore it is very sensitive to wind effects. As a result the water levels along the coasts are, in addition to the tidal oscillations subject to a considerable wind setup and exceptionally severe gales throughout history have been accompanied by inundations of the low-lying regions bordering the North Sea, in particular its southern part. No stretch of coast has suffered more than that belonging to the Netherlands and the adjacent parts of Belgium and North Western Germany. Several factors combine to bestow on us this doubtful privilege.


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