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The world’s coasts and deltas are progressively threatened by climate change and human activities. The degree at which coastlines can adapt to these changes strongly depends on the sediment availability. The availability of muddy sediments is however poorly known. This study aims at developing a mud budget for the world’s largest system of uninterrupted tidal flats: the Wadden Sea. The resulting mud budget is nearly closed: ~ 12 million ton/year enters the system on its western end, ~ 1.5 million ton/year is added by local rivers, while ~ 12 million ton annually deposits or is extracted by anthropogenic activities. A mud deficit already exists in the downdrift areas, which will only become more pronounced with increased sea level rise rates. Mud is thus a finite resource similar to sand, and should be treated as such in sediment management strategies. Resolving future challenges will therefore require a cross-border perspective on sediment management., Coastal Engineering, Environmental Fluid Mechanics

Tidal estuaries are often characterized by estuarine turbidity maxima (ETM), impacting physical, biogeochemical, and ecological dynamics along the land-sea continuum. Mechanisms driving ETM formation are now relatively well understood and ETM responses to environmental conditions are well characterized. However, a realistic description of estuarine sediment dynamics currently requires extensive in-situobservations and fully-validated numerical modeling. Such time-consuming and costly approaches limit their use for estuary stakeholders. The main goal of this study is to provide an estimate of the maximum suspended sediment concentration (SSC) that can be expected in tidal estuaries, based on key estuarine parameters, i.e., tidal range (a), river discharge, water depth (h), and estuary shape. Seven meso- to macro-tidal NW European estuaries have been analyzed using a combination of in-situ measurements and realistic numerical simulations (Elbe, Weser, Scheldt, Seine, Loire, Gironde, and Ems estuaries). These estuaries present contrasted estuarine forcing, in terms of tidal range (from 2 to 8 m), mean river discharge (from 100 to 900 m3/s), and estuary length (from 100 to 190 km). It results in maximum surface SSC ranging from 0.2 to 5 kg/m3. Results show that the classical parameter space used for estuarine circulation classification, based on the freshwater Froude number and mixing number, is not well adapted to SSC classification. It is mainly due to not considering tidal asymmetry effects. However, the relative tidal range (i.e., the tidal range over channel depth ratio, a/h) is more relevant than the mixing number to characterize estuarine SSC, as it is related to both tidal energy and tidal asymmetries. Therefore, Frf and a/h provide an interesting parameter space to classify ETM, where SSC primarily increases with a/h, and secondly increases with Frf (Figure 1). Nonetheless, the seven investigated estuaries correspond to strongly stratified and partially mixed

Marine spatial planning requires reliable data for, e.g., the design of coastal structures, research, or sea level rise adaptation. This task is particularly ambiguous in the German Bight (North Sea, Europe) because a compromise must be found between economic interests and biodiversity since the environmental status is monitored closely by the European Union. For this reason, we have set up an open-access, integrated marine data collection for the period from 1996 to 2015. It provides bathymetry, surface sediments, tidal dynamics, salinity, and waves for the German Bight and is of interest to stakeholders in science, government, and the economy. This part of a two-part publication presents data from numerical hindcast simulations for sea surface elevation, depth-averaged current velocity, bottom shear stress, depth-averaged salinity, wave parameters, and wave spectra. As an improvement to existing data collections, our data represent the variability in the bathymetry by using annually updated model topographies. Moreover, we provide data at a high temporal and spatial resolution (Hagen et al., 2020b); i.e., numerical model results are gridded to 1000 m at 20 min intervals (https://doi.org/10.48437/02.2020.K2.7000.0004). Tidal characteristic values (Hagen et al., 2020a), such as tidal range or ebb current velocity, are computed based on numerical modeling results (https://doi.org/10.48437/02.2020.K2.7000.0003). Therefore, this integrated marine data collection supports the work of coastal stakeholders and scientists, which ranges from developing detailed coastal models to handling complex natural-habitat problems or designing coastal structures. Copyright, Bundesministerium für Verkehr und digitale Infrastruktur

Im Rahmen des Verbundprojektes EasyGSH-DB unter Leitung der BAW werden flächendeckende, harmonisierte und qualitätsgesicherte Referenzdatensätze für Geomorphologie und Sedimentologie sowie Hydrodynamik in der Deutschen Bucht erarbeitet. Hierzu werden alle verfügbaren und um-fangreichen Naturmessdaten mit unterschiedlichen im Vorhaben z. T. neu entwickelten daten- und prozessbasierten Simulationsmodellen verknüpft. Aus den anschließend durchgeführten numeri-schen Simulationen über einen Zeitraum von 20 Jahren (Hindcast: 1996 - 2015) resultieren zeitlich und räumlich hochaufgelöste synoptische Referenzdatensätze. Zusammen mit zahlreichen Analysen werden hiermit die EasyGSH-Produkte abgeleitet und der (Fach-) Öffentlichkeit als Ausgangsdaten für eigene Anwendungen zur freien Verfügung gestellt., Bundesministerium für Verkehr und digitale Infrastruktur