scholarly journals The ‘Voordelta’, the contiguous ebb-tidal deltas in the SW Netherlands: large-scale morphological changes and sediment budget 1965–2013; impacts of large-scale engineering

2016 ◽  
Vol 96 (3) ◽  
pp. 233-259 ◽  
Author(s):  
Edwin P.L. Elias ◽  
Ad J.F. van der Spek ◽  
Marian Lazar
Keyword(s):  
Large Scale ◽  
Morphological Changes ◽  
Tidal Flow ◽  
Sediment Budget ◽  
Delta Front ◽  
Knowledge Based ◽  
The North ◽  
Sediment Volume ◽  
Ebb Tidal Delta ◽  
The Individual

AbstractThe estuaries in the SW Netherlands, a series of distributaries of the rivers Rhine, Meuse and Scheldt known as the Dutch Delta, have been engineered to a large extent as part of the Delta Project. The Voordelta, a coalescing system of the ebb-tidal deltas of these estuaries, extendsc.10 km offshore and coversc.90 km of the coast. The complete or partial damming of the estuaries had an enormous impact on the ebb-tidal deltas. The strong reduction of the cross-shore directed tidal flow triggered a series of morphological changes that continue until today. This paper aims to give a concise overview of half a century of morphological changes and a sediment budget, both for the individual ebb-tidal deltas and the Voordelta as a whole, based on the analysis of a unique series of frequent bathymetric surveys. The well-monitored changes in the Voordelta, showing the differences in responses of the ebb-tidal deltas, provide clear insight into the underlying processes. Despite anthropogenic dominance, knowledge based on natural inlets can still explain the observed developments. Complete damming of the three northern estuaries Brielse Maas, Haringvliet and Grevelingen resulted in a regime shift, from mixed-energy to wave-dominated, and sediments are transported in landward and downdrift direction. This results in large morphodynamic changes – sediments are redistributed from the delta front landward – but small net volume changes – a 0.1–0.2 × 106m3a−1increase in volume over the period 1965–2010 – since the dams block sediment transport into the estuaries. Sediment volume losses of 106m3a−1are observed on the ebb-tidal delta of the partially closed Eastern Scheldt and still open Western Scheldt estuary. As a result of a reduction of the estuarine tide in the mouth of the Eastern Scheldt, the north–south-running North Sea tidal wave has gained impact on its ebb-tidal delta, which causes morphological adjustments and erosion of the Banjaard shoal area. Moreover, the Eastern Scheldt ebb-tidal delta delivers sediment to its neighbours. The stable ebb-tidal delta configuration in the Western Scheldt, despite major dredging activities, illustrates that these large inlet systems are robust and resilient to significant anthropogenic change, as long as the balance between the dominant hydrodynamic processes (tides and waves) does not alter significantly.

Do Statistical Pattern Corrections Improve Seasonal Climate Predictions in the North American Multimodel Ensemble Models?

2017 ◽  
Vol 30 (20) ◽  
pp. 8335-8355 ◽  
Author(s):  
Anthony G. Barnston ◽  
Michael K. Tippett
Keyword(s):  
North American ◽  
Large Scale ◽  
Climate Model ◽  
Principal Component ◽  
Eastern Africa ◽  
Multimodel Ensemble ◽  
Anomaly Correlation ◽  
The North ◽  
The Individual ◽  
North American Multimodel Ensemble

Abstract Canonical correlation analysis (CCA)-based statistical corrections are applied to seasonal mean precipitation and temperature hindcasts of the individual models from the North American Multimodel Ensemble project to correct biases in the positions and amplitudes of the predicted large-scale anomaly patterns. Corrections are applied in 15 individual regions and then merged into globally corrected forecasts. The CCA correction dramatically improves the RMS error skill score, demonstrating that model predictions contain correctable systematic biases in mean and amplitude. However, the corrections do not materially improve the anomaly correlation skills of the individual models for most regions, seasons, and lead times, with the exception of October–December precipitation in Indonesia and eastern Africa. Models with lower uncorrected correlation skill tend to benefit more from the correction, suggesting that their lower skills may be due to correctable systematic errors. Unexpectedly, corrections for the globe as a single region tend to improve the anomaly correlation at least as much as the merged corrections to the individual regions for temperature, and more so for precipitation, perhaps due to better noise filtering. The lack of overall improvement in correlation may imply relatively mild errors in large-scale anomaly patterns. Alternatively, there may be such errors, but the period of record is too short to identify them effectively but long enough to find local biases in mean and amplitude. Therefore, statistical correction methods treating individual locations (e.g., multiple regression or principal component regression) may be recommended for today’s coupled climate model forecasts. The findings highlight that the performance of statistical postprocessing can be grossly overestimated without thorough cross validation or evaluation on independent data.

scholarly journals The geomorphic features of the landslide on Kuprin St. in Khmelnytskyi City

2018 ◽  
pp. 143-151
Author(s):  
Oksana Koltun
Keyword(s):  
Large Scale ◽  
Morphological Changes ◽  
Maximum Height ◽  
Main Body ◽  
Left Bank ◽  
The North ◽  
Lower Terrace ◽  
Early Twenty ◽  
Geomorphic Features ◽  
Loess Landslides

The landslide in Quaternary loess sediments occurs a balka at the Samets River left bank and is limited by Metropolitan Sheptytsky St. in the West, Kuprin St. in the North, Kuprin lane in the East (the last locates 140–250 m to the East of the plot), two ponds in the South. The elevation between Kuprin St. and ponds distinguish 42 m, the length from North to South 820 m, and the width 390 m. The exact dates of landslide shift, as well as geological, cartographic or other materials like that at the time of sliding (the end of the 1950s for the first shift and the first half of the 1970s for the second one) were not found, this research bases on reconstruction of terrain morphology by large-scale maps, plans from the late nineteenth till early twenty-first centuries. Balka’s slopes and the adjacent areas of the loess plateau undergone significant morphological changes after the landslide, modern terrain is allocated to anthropogenic surfaces, such as plane watershed, built-up without significant vertical planning; built-up terraced slopes of plateau, balkas and riverbank; three artificial terraces on the main body, as well as steep and very steep ledges and outcrops (maximum height 9 m), surfaces with mosaic combination of small terraces, flattering slopes and steep ledges, hilled surface. The landslide toe came to the flood terrace; this part of the landslide was later completely changed after construction of the dam, ponds and channel in the late 1980s. There is a connection between earlier anthropogenic terrain changes and landslide: first of all, the eastern and western scarps were connected to the ledges of quarries. The modern lower terrace has approximately the same absolute heights as level of the western quarry area before sliding. The north scarp mostly repeated the contour shape of balka but smoothed out smaller bends. In the Northeast, the landslide captured part of the plateau, the present level of the middle terrace is close to the eastern quarry level. Because of landsliding and repeated redevelopment of the territory, the situation with the slope exposures was simplified: except for the scarps, southern exposures dominate. In 2015 curved tree trunks, tilted poles, cracks and other destruction of buildings indicate the slow earthflow within the area. Key words: urban landslides, loess landslides, terrain morphology, Khmelnytskyi City.

scholarly journals From Ripples to Large-Scale Sand Transport: The Effects of Bedform-Related Roughness on Hydrodynamics and Sediment Transport Patterns in Delft3D

2020 ◽  
Vol 8 (11) ◽  
pp. 892
Author(s):  
Laura Brakenhoff ◽  
Reinier Schrijvershof ◽  
Jebbe van der Werf ◽  
Bart Grasmeijer ◽  
Gerben Ruessink ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Water Movement ◽  
Small Scale ◽  
Sand Transport ◽  
Influence Model ◽  
The North ◽  
Ebb Tidal Delta ◽  
Transport Patterns ◽  
Set Up

Bedform-related roughness affects both water movement and sediment transport, so it is important that it is represented correctly in numerical morphodynamic models. The main objective of the present study is to quantify for the first time the importance of ripple- and megaripple-related roughness for modelled hydrodynamics and sediment transport on the wave- and tide-dominated Ameland ebb-tidal delta in the north of the Netherlands. To do so, a sensitivity analysis was performed, in which several types of bedform-related roughness predictors were evaluated using a Delft3D model. Also, modelled ripple roughness was compared to data of ripple heights observed in a six-week field campaign on the Ameland ebb-tidal delta. The present study improves our understanding of how choices in model set-up influence model results. By comparing the results of the model scenarios, it was found that the ripple and megaripple-related roughness affect the depth-averaged current velocity, mainly over the shallow areas of the delta. The small-scale ripples are also important for the suspended load sediment transport, both indirectly through the affected flow and directly. While the current magnitude changes by 10–20% through changes in bedform roughness, the sediment transport magnitude changes by more than 100%.

scholarly journals Unravelling the impacts of precipitation, temperature and land-cover change for extreme drought over the North American High Plains

2018 ◽  
Author(s):  
Annette Hein ◽  
Laura Condon ◽  
Reed Maxwell
Keyword(s):  
Land Cover ◽  
Large Scale ◽  
Hydrologic Model ◽  
Drought Severity ◽  
High Plains ◽  
The North ◽  
Disturbed Land ◽  
Physically Based ◽  
Integrated Hydrologic Model ◽  
The Individual

Abstract. Drought is a natural disaster that may become more common in the future under climate change. It involves changes to temperature, precipitation, and/or land cover, but the relative contributions of each of these factors to overall drought severity is not clear. Here we apply a high-resolution integrated hydrologic model of the High Plains to explore the individual importance of each of these factors and the feedbacks between them. The model was constructed using ParFlow-CLM, which represents surface and subsurface processes in detail with physically based equations. Numerical experiments were run to perturb vegetation, precipitation and temperature separately and in combination. Results show that decreased precipitation caused larger anomalies in evapotranspiration, soil moisture, stream flow and water table levels than did increased temperature or disturbed land cover. However, these factors are not linearly additive when applied in combination; some effects of multi-factor runs came from interactions between temperature, precipitation and land cover. Spatial scale was important in characterizing impacts, as unpredictable and nonlinear impacts at small scales aggregate to predictable, linear large scale behaviour.

scholarly journals A Brief Climatology of Dunkelflaute Events over and Surrounding the North and Baltic Sea Areas

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6508
Author(s):  
Bowen Li ◽  
Sukanta Basu ◽  
Simon J. Watson ◽  
Herman W. J. Russchenberg
Keyword(s):  
Renewable Energy ◽  
Baltic Sea ◽  
Large Scale ◽  
Solar Power ◽  
Weather Condition ◽  
Power Production ◽  
Energy System ◽  
The North ◽  
The Individual ◽  
Almost All

In the coming decades, the European energy system is expected to become increasingly reliant on non-dispatchable generation such as wind and solar power. Under such a renewable energy scenario, a better characterization of the extreme weather condition ‘Dunkelflaute’, which can lead to a sustained reduction of wind and solar power, is important. In this paper, we report findings from the very first climatological study of Dunkelflaute events occurring in eleven countries surrounding the North and Baltic Sea areas. By utilizing multi-year meteorological and power production datasets, we have quantified various statistics pertaining to these events and also identified their underlying meteorological drivers. It was found that almost all periods tagged as Dunkelflaute events (with a length of more than 24 h) are in November, December, and January for these countries. On average, there are 50–100 h of such events happening in each of these three months per year. The limited wind and solar power production during Dunkelflaute events is shown to be mainly driven by large-scale high-pressure systems and extensive low-cloud coverage. Even though the possibility of simultaneous Dunkelflaute events in neighboring countries can be as high as 30–40%, such events hardly occur simultaneously in all the eleven countries. Through an interconnected EU-11 power system, the mean frequency of Dunkelflaute drops from 3–9% for the individual countries to approximately 3.5% for the combined region, highlighting the importance of aggregating production over a wide area to better manage the integration of renewable energy generation.

scholarly journals On the Remote Drivers of Rainfall Variability in Australia

2009 ◽  
Vol 137 (10) ◽  
pp. 3233-3253 ◽  
Author(s):  
James S. Risbey ◽  
Michael J. Pook ◽  
Peter C. McIntosh ◽  
Matthew C. Wheeler ◽  
Harry H. Hendon
Keyword(s):  
Large Scale ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Southern Annular Mode ◽  
Wet Season ◽  
The North ◽  
Eastern Australia ◽  
Different Seasons ◽  
The Individual

Abstract This work identifies and documents a suite of large-scale drivers of rainfall variability in the Australian region. The key driver in terms of broad influence and impact on rainfall is the El Niño–Southern Oscillation (ENSO). ENSO is related to rainfall over much of the continent at different times, particularly in the north and east, with the regions of influence shifting with the seasons. The Indian Ocean dipole (IOD) is particularly important in the June–October period, which spans much of the wet season in the southwest and southeast where IOD has an influence. ENSO interacts with the IOD in this period such that their separate regions of influence cover the entire continent. Atmospheric blocking also becomes most important during this period and has an influence on rainfall across the southern half of the continent. The Madden–Julian oscillation can influence rainfall in different parts of the continent in different seasons, but its impact is strongest on the monsoonal rains in the north. The influence of the southern annular mode is mostly confined to the southwest and southeast of the continent. The patterns of rainfall relationship to each of the drivers exhibit substantial decadal variability, though the characteristic regions described above do not change markedly. The relationships between large-scale drivers and rainfall are robust to the selection of typical indices used to represent the drivers. In most regions the individual drivers account for less than 20% of monthly rainfall variability, though the drivers relate to a predictable component of this variability. The amount of rainfall variance explained by individual drivers is highest in eastern Australia and in spring, where it approaches 50% in association with ENSO and blocking.

scholarly journals A CLASSIFICATION METHOD FOR THE PRESENCE OF TIDAL SAND WAVES AND MAINTENANCE DREDGING DESIGN

2018 ◽  
pp. 48
Author(s):  
Rick De Koning ◽  
Jaap van Thiel De Vries ◽  
Bas Borsje
Keyword(s):  
Large Scale ◽  
Tidal Flow ◽  
Narrow Channel ◽  
Sand Wave ◽  
Maintenance Strategies ◽  
Sand Waves ◽  
Recirculating Flow ◽  
The North ◽  
Tidal Sand ◽  
And Migration

The study into sand wave dynamics in South Channel commenced after large dune forms were observed in monitoring campaigns following the channel deepening project of the Port of Melbourne. The project involved deepening of the harbor berths and channels, but more importantly, it involved the deepening of South Channel in Port Phillip Bay. South Channel, the main shipping channel, crosses the bay over ≈20km. The growth of bedforms at various locations in South Channel now threatens to impede marine traffic. The dimensions and migration rate of the bedforms in the channel are remarkable, especially in the harsh flow conditions in the narrow channel. Therefore, the bedforms in South Channel cannot be given an obvious classification. In this paper it is shown that the bedforms in South Channel can be classified as a tidal sand wave type with a method that requires only insight in water depth, tidal flow velocity and grain size. Tidal sand waves are large-scale bedforms generated by recirculating flow cells that drive sediment to the top of a crest and are commonly observed on shallow coastal seas such as the North Sea. The bedform concern in the channel illustrates the necessity of an evaluation of the present, and alternative, channel maintenance strategies. A numerical model in Delft3D software is applied, along with a probabilistic calculation that combines insights from the simulations and survey data, to assess different maintenance strategies.

scholarly journals Evaluating the relative importance of precipitation, temperature and land-cover change in the hydrologic response to extreme meteorological drought conditions over the North American High Plains

2019 ◽  
Vol 23 (4) ◽  
pp. 1931-1950 ◽  
Author(s):  
Annette Hein ◽  
Laura Condon ◽  
Reed Maxwell
Keyword(s):  
Land Cover ◽  
Large Scale ◽  
Meteorological Drought ◽  
Hydrologic Model ◽  
Drought Severity ◽  
High Plains ◽  
The North ◽  
Physically Based ◽  
Integrated Hydrologic Model ◽  
The Individual

Abstract. Drought is a natural disaster that may become more common in the future under climate change. It involves changes to temperature, precipitation and/or land cover, but the relative contributions of each of these factors to overall drought severity is not clear. Here we apply a high-resolution integrated hydrologic model of the High Plains to explore the individual importance of each of these factors and the feedbacks between them. The model was constructed using ParFlow-CLM, which represents surface and subsurface processes in detail with physically based equations. Numerical experiments were run to perturb vegetation, precipitation and temperature separately and in combination. Results show that decreased precipitation caused larger anomalies in evapotranspiration, soil moisture, stream flow and water table levels than increased temperature or disturbed land cover did. However, these factors are not linearly additive when applied in combination; some effects of multifactor runs came from interactions between temperature, precipitation and land cover. Spatial scale was important in characterizing impacts, as unpredictable and nonlinear impacts at small scales aggregate to predictable, linear large-scale behavior.

scholarly journals Morphological change in Newfoundland caribou: Effects of abundance and climate

Rangifer ◽  
2011 ◽  
Vol 31 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Shane P. Mahoney ◽  
Jackie N. Weir ◽  
J. Glenn Luther ◽  
James A. Schaefer ◽  
Shawn F. Morrison
Keyword(s):  
Large Scale ◽  
Rangifer Tarandus ◽  
Morphological Changes ◽  
Population Abundance ◽  
Adult Males ◽  
The North ◽  
Antler Size ◽  
Mandible Length ◽  
Males And Females ◽  
The North Atlantic Oscillation

The demographic and environmental influences on large mammal morphology are central questions in ecology. We investigated the effects of population abundance and climate on body size and number of male antler points for the La Poile and Middle Ridge caribou (Rangifer tarandus, L. 1758) herds, Newfoundland, Canada. Across 40 years and 20-fold changes in abundance, adult males and females exhibited diminished stature as indicated by jawbone size (diastema and total mandible length) and the number of antler points at the time of harvest. Associations between jawbone size and population abundance at birth were consistently negative for both herds, both sexes, and all age classes. Large-scale climate patterns, as measured by the North Atlantic Oscillation in the winter prior to birth, were also negatively associated with jawbone size. Declines in male antler size, as measured by the number of antler points, were not well predicted by either abundance or climate, suggesting other factors (e.g., current, rather than latent, foraging conditions) may be involved. We conclude that these morphological changes indicate competition for food resources.

Sign in / Sign up

Export Citation Format

Share Document