Databased simulation and reconstruction of the near shore geomorphological structure and sediment composition of the German tidal flats

Abstract

<p>With an area of almost 10,000 km², the project area represents the tidal flats on Germany’s North Sea coast. The tidal flats and their channels as well as morphologically highly active estuarine systems undergo significant erosional and sedimentational processes that prove difficult the assessment of sedimentological composition based on relatively few and temporally far stretched field measurements. The holistic databased simulation of both the internal structure of the soil itself and its sedimentary composition is based on around 21,000 measured surface sediment samples (from 1949 until recent) and yearly consistent digital bathymetric models, starting 1950, spatiotemporally interpolated in a 10 m grid resolution by the Functional Seabed Model. By utilizing the high temporal and spatial resolution of the bathymetric models, it is possible to quantify the seabed depth evolution (sedimentation and erosion) and to solve a differential equation to capture sedimentary evolution, a consistent and continuous three dimensional model of both the surface and the subsurface structures and sedimentary compositions can be generated. To further extend the volumetric extent of the model, around 16,000 sedimentary core samples are used to fill the spatial and consequently the temporal void between the lowest altitudinal range of validity of the aforementioned model segment to the lower boundary of the target model volume. This boundary is set to be the lower limit of the morphologically active or activatable space, which contains the volume of sediment that could be eroded in current climate conditions. The limit, generally speaking, can be expected to somewhat coincide with the base of Holocene sediments, as Pleistocene sediments – especially subglacial tills – generally take higher amounts of bottom shear stress to erode than unindurated Holocene sediments, which usually form tidal flat sediments. The purpose of the generated three dimensional model is to be able to derive sedimentological information in both custom spatial resolution as well as custom sedimentological classification as base and validation data for process based morphodynamic simulation models. With these enhanced models, the quality of the prognosis of morphological developments and stability of coastal areas as a tool for planning processes for coastal protection and maritime economy is expected to be increased.</p>

Paleo‐Hydrogeological Modeling to Understand Present‐Day Groundwater Salinities in a Low‐Lying Coastal Groundwater System (Northwestern Germany)

“…Relative sea levels were ∼120-130 m lower than the present-day sea level at the end of the Pleistocene (∼25,000-20,000 years before the present [BP], Spratt & Lisiecki, 2016). As such, the model region was >400 km distant from the coast at that time (Ehlers et al, 2011), considering −37 masl as the minimum surface elevation in the modeled area (LBEG, 2000;Sievers et al, 2020). The global Late Pleistocene sea-level minimum was followed by fast SLR with rates in the range of ∼1 m per century (c) −1 until ∼9000 BP (Spratt & Lisiecki, 2016).…”

An Integrated Marine Data Collection for the German Bight – Part I: Subaqueous Geomorphology and Surface Sedimentology

“…As it was designed to be highly modular, it can therefore be expanded with new components very easily. Currently, the integration of the subsurface sediment composition of the morphologically active or activatable space is under development (see methodology excerpt in conference presentation Sievers et al, 2020) in the publicly funded KFKI project "Stratigraphic Model Components for the Improvement of High-Resolution and Regionalized Morphodynamic Simulation Models" (SMMS) in cooperation with the German Federal Waterways Engineering and Research Institute and the Federal Maritime and Hydrographic Agency of Germany. SMMS aims to provide consistent and continuous stratigraphical data of the sub-seafloor and adjacent estuaries to further improve the ability of hydrodynamic numerical model systems to assess erosional processes.…”

An integrated marine data collection for the German Bight – Part 1: Subaqueous geomorphology and surface sedimentology (1996–2016)

“…As it was designed to be highly modular, it can therefore be expanded with new components very easily. Currently, the integration of the subsurface sediment composition of the morphologically active or activatable space is under development (see methodology excerpt in the conference presentation of Sievers et al, 2020) in the publicly funded KFKI project "Stratigraphic Model Components for the Improvement of High-Resolution and Regionalized Morphodynamic Simulation Models" (SMMS) in cooperation with the German Federal Waterways Engineering and Research Institute and the Federal Maritime and Hydrographic Agency of Germany. SMMS aims to provide consistent and continuous stratigraphical data of the sub-seafloor and adjacent estuaries to further improve the ability of hydrodynamic numerical model systems to assess erosional processes.…”