Data report: geology of reef-front carbonate sediment deposits around Oahu, Hawaii

2003 ◽  
Author(s):  
Monty A. Hampton ◽  
Charles T. Blay ◽  
Christopher Murray ◽  
Laura Z. Torresan ◽  
Cathy S. Frazee ◽  
...  
Keyword(s):  
Carbonate Sediment ◽  
Sediment Deposits

Carbonate Sediment Deposits on the Reef Front Around Oahu, Hawaii

2004 ◽  
Vol 22 (1-2) ◽  
pp. 65-102 ◽  
Author(s):  
MONTY A. HAMPTON ◽  
CHARLES T. BLAY ◽  
CHRISTOPHER J. MURRAY
Keyword(s):  
Carbonate Sediment ◽  
Sediment Deposits

Principles and approaches for numerical modelling of sediment transport in sewers

1995 ◽  
Vol 31 (7) ◽  
pp. 107-115 ◽  
Author(s):  
Ole Mark ◽  
Cecilia Appelgren ◽  
Torben Larsen
Keyword(s):  
Mathematical Model ◽  
Sediment Transport ◽  
Numerical Modelling ◽  
Simple Application ◽  
Sewer Systems ◽  
Sediment Deposits ◽  
Model Mouse ◽  
Modelling Approaches

A study has been carried out with the objectives of describing the effect of sediment deposits on the hydraulic capacity of sewer systems and to investigate the sediment transport in sewer systems. A result of the study is a mathematical model MOUSE ST which describes sediment transport in sewers. This paper discusses the applicability and the limitations of various modelling approaches and sediment transport formulations in MOUSE ST. Further, the paper presents a simple application of MOUSE ST to the Rya catchment in Gothenburg, Sweden.

Using reservoir sediment deposits to determine the longer-term fate of chernobyl-derived 137Cs fallout in the fluvial system

2021 ◽  
Vol 274 ◽  
pp. 116588
Author(s):  
M.M. Ivanov ◽  
A.V. Konoplev ◽  
D.E. Walling ◽  
E.A. Konstantinov ◽  
A.L. Gurinov ◽  
...  
Keyword(s):  
Fluvial System ◽  
Reservoir Sediment ◽  
Sediment Deposits ◽  
137Cs Fallout

scholarly journals Watershed Suspended Sediment Supply and Potential Impacts of Dam Removals for an Estuary

2021 ◽  
Author(s):  
David K. Ralston ◽  
Brian Yellen ◽  
Jonathan D. Woodruff
Keyword(s):  
Suspended Sediment ◽  
River Estuary ◽  
Dam Removal ◽  
Hudson River ◽  
Sediment Traps ◽  
Sediment Supply ◽  
Watershed Area ◽  
Natural Lakes ◽  
Sediment Deposits ◽  
Dam Removals

AbstractObservations and modeling are used to assess potential impacts of sediment releases due to dam removals on the Hudson River estuary. Watershed sediment loads are calculated based on sediment-discharge rating curves for gauges covering 80% of the watershed area. The annual average sediment load to the estuary is 1.2 Mt, of which about 0.6 Mt comes from side tributaries. Sediment yield varies inversely with watershed area, with regional trends that are consistent with substrate erodibility. Geophysical and sedimentological surveys in seven subwatersheds of the Lower Hudson were conducted to estimate the mass and composition of sediment trapped behind dams. Impoundments were classified as (1) active sediment traps, (2) run-of-river sites not actively trapping sediment, and (3) dammed natural lakes and spring-fed ponds. Based on this categorization and impoundment attributes from a dam inventory database, the total mass of impounded sediment in the Lower Hudson watershed is estimated as 4.9 ± 1.9 Mt. This represents about 4 years of annual watershed supply, which is small compared with some individual dam removals and is not practically available given current dam removal rates. More than half of dams impound drainage areas less than 1 km2, and play little role in downstream sediment supply. In modeling of a simulated dam removal, suspended sediment in the estuary increases modestly near the source during discharge events, but otherwise effects on suspended sediment are minimal. Fine-grained sediment deposits broadly along the estuary and coarser sediment deposits near the source, with transport distance inversely related to settling velocity.

Sea level response to Quartenary erosion and deposition in Scandinavia 

2021 ◽  
Author(s):  
Gustav Pallisgaard-Olesen ◽  
Vivi Kathrine Pedersen ◽  
Natalya Gomez
Keyword(s):  
Sea Level ◽  
Sea Level Changes ◽  
Glacial Cycles ◽  
Glacial Erosion ◽  
Erosion And Deposition ◽  
Late Pliocene ◽  
Glacial Origin ◽  
Sediment Deposits ◽  
Mass Redistribution ◽  
Global Sea Level

<div> <p>The landscape in western Scandinavia has undergone dramatic changes through numerous glaciations during the Quaternary. These changes in topography and in the volumes of offshore sediment deposits, have caused significant isostatic adjustments and local sea level changes, owing to erosional unloading and depositional loading of the lithosphere. Mass redistribution from erosion and deposition also has the potential to cause significant pertubations of the geoid, resulting in additional sea-level changes. The combined sea-level response from these processes, is yet to be investigated in detail for Scandinavia.</p> </div><div> <p>In this study we estimate the total sea level change from late-Pliocene- Quaternary glacial erosion and deposition in the Scandinavian region, using a gravitationally self-consistent global sea level model that includes the full viscoelastic response of the solid Earth to surface loading and unloading. In addition to the total late Pliocene-Quaternary mass redistribution, we <span>also </span>estimate transient sea level changes related specifically to the two latest glacial cycles.</p> </div><div> <p>We utilize existing observations of offshore sediment thicknesses of glacial origin, and combine these with estimates of onshore glacial erosion and estimates of erosion on the inner shelf. Based on these estimates, we can define mass redistribution and construct a preglacial landscape setting.</p> </div><div> <p>Our preliminary results show <span>perturbations of</span> the local sea level up to ∼ 200 m since<span> the</span> late-Pliocene in the Norwegian Sea, suggesting that erosion and deposition ha<span>ve</span> influenced the local paleo sea level history in Scandinavia significantly.</p> </div>

scholarly journals Application of the adjoint approach to optimise the initial conditions of a turbidity current

2016 ◽  
Author(s):  
Samuel D. Parkinson ◽  
Simon W. Funke ◽  
Jon Hill ◽  
Matthew D. Piggott ◽  
Peter A. Allison
Keyword(s):  
Initial Conditions ◽  
Current Model ◽  
Deep Ocean ◽  
Turbidity Current ◽  
Significant Advance ◽  
Turbidity Currents ◽  
General Behaviour ◽  
Depositional Processes ◽  
Sediment Deposits ◽  
Adjoint Approach

Abstract. Turbidity currents are one of the main drivers for sediment transport from the continental shelf to the deep ocean. The resulting sediment deposits can reach hundreds of kilometres into the ocean. Computer models that simulate turbidity currents and the resulting sediment deposit can help to understand their general behaviour. However, in order to recreate real-world scenarios, the challenge is to find the turbidity current parameters that reproduce the observations of sediment deposits. This paper demonstrates a solution to the inverse sediment transportation problem: for a known sedimentary deposit, the developed model reconstructs details about the turbidity current that produced these deposits. The reconstruction is constrained here by a shallow water sediment-laden density current model, which is discretised by the finite element method and an adaptive time-stepping scheme. The model is differentiated using the adjoint approach and an efficient gradient-based optimisation method is applied to identify turbidity parameters which minimise the misfit between modelled and observed field sediment deposits. The capabilities of this approach are demonstrated using measurements taken in the Miocene-age Marnoso Arenacea Formation (Italy). We find that whilst the model cannot match the deposit exactly due to limitations in the physical processes simulated, it provides valuable insights into the depositional processes and represents a significant advance in our toolset for interpreting turbidity current deposits.

Organic near-bed fluid and particulate transport in combined sewers

1995 ◽  
Vol 31 (7) ◽  
pp. 61-68 ◽  
Author(s):  
E. Ristenpart ◽  
R. M. Ashley ◽  
M. Uhl
Keyword(s):  
Bed Load ◽  
Erosion And Deposition ◽  
Sediment Bed ◽  
Solids Transport ◽  
Particulate Transport ◽  
Sediment Deposits ◽  
Dense Fluid ◽  
Deposition Processes ◽  
Continuous Field ◽  
Heterogeneity Of Solids

Studies in Germany, Belgium, France and Scotland have revealed that there are significant solids transport gradients in the depth of foul and combined sewage flows. Continuous field observations of changes in depths of sediment deposits in combined sewers have also indicated that there is an interaction between the erosion and deposition processes and changes in the mass transport of solids in regions in the overlying flow. A fuller understanding of the interactive phenomena is essential for both sewer sediment management and the minimization of associated pollution from wash-out of solids via CSOs. The paper presents results from the detailed studies in Hildesheim, Germany and those carried out in Dundee, Scotland, investigating the heterogeneity of solids movement with regard to gross solids, erosion of sewer sediments and their interactions with the suspended transport phases and the layer of very dense fluid found to be transported under certain circumstances, near the sediment bed or sewer invert (traditionally called ‘bed-load’).

scholarly journals Estimation of Holocene bedload sedimentation rate in a paleo-drowned river-valley (Middle Harbour, Sydney estuary, Australia)

2022 ◽  
Author(s):  
Stephen P Lound ◽  
Gavin F Birch ◽  
Deirdre Dragovich
Keyword(s):  
Seismic Data ◽  
Fine Sediment ◽  
River Valley ◽  
Sedimentation Rates ◽  
Suspended Material ◽  
Last Glacial Period ◽  
Sediment Deposits ◽  
Sydney Estuary ◽  
Over The Top ◽  
The Last Glacial

Abstract Middle Harbour is a drowned-river valley located adjacent to the larger Sydney estuary, Australia. Extensive, high-resolution seismic data were correlated with borehole, land use, topographical, and geological data to calculate the mass of genetically different sediment deposits in Middle Harbour. The Harbour follows a well-defined drowned river-valley structure featuring small fluvial bedload delta deposits in the upper reaches of the embayments, a deep, central extensive mud basin overlying transgressive basal accumulations and a large flood-tide delta at the entrance. Deposits of an estimated 5,094 t of bedload, 21,143 t of suspended sediment and 5,947 t of transgressive basal material located in the estuary provided sedimentation rates of 0.68 t y-1, 1.29 t y-1, and 2.86 t y -1 respectively. These rates, determined from measured accumulations, were surprisingly low and substantially smaller than modelled rates. However, low sedimentation rates for suspended material may be due to fine sediment escaping over the top of the marine tidal delta, which effectively traps all bedload material from exiting the Harbour. Results of this study indicate that Holocene bedload sedimentation in Middle Harbour was slow and regular until a rapid increase after urbanisation commenced in the catchment. Most pre-Holocene material was eroded from Middle Harbour during the Last Glacial period with sediment currently present in the estuary having been deposited since sea-level recovery.

scholarly journals Speleogenesis and depositional hystory of paleokarst phreatic caves/cavities; Podgrad, SW Slovenia

2021 ◽  
Author(s):  
Bojan Otoničar
Keyword(s):  
Host Rock ◽  
Upper Cretaceous ◽  
Coarse Grained ◽  
Mixing Zone ◽  
Carbonate Sediment ◽  
Lower Eocene ◽  
The Third ◽  
Cave Sediments ◽  
Upper Paleocene ◽  
Δ13c And Δ18o

The studied palaeokarst corresponds to an uplifted peripheral foreland bulge when Upper Cretaceous diagenetically immature eugenetic carbonates were subaerially exposed, karstified and subsequently overlain by upper Paleocene/lower Eocene palustrine limestone. Among the subsurface paleokarstic features, both vadose and phreatic forms occur.  The phreatic caves/cavities include features characteristic of the mixing zone speleogenesis at the interface between freshwater (brackish water) lenses and the underlying seawater. They were found in various positions with respect to the paleokarstic surface, the deepest being about 75 m below the surface. Three indistinct horizons of cavities/caves and intermediate vugs were recognized. Subsequently, all cavities were completely filled with detrital sediments and speleothems in the phreatic and vadose zones. In general, the phreatic cavities of the lower two horizons are geopetally filled with mudstone derived from incomplete dissolution of the host rock and overlain by coarse-grained, blocky calcite. Shallower below the paleokarst surface, a large phreatic cave of the third horizon is filled with flowstone overlain by reddish micritic carbonate sediment with intercalated calcite rafts. In the upper part of the cave, sediments derived from the paleokarst surface are gradually becoming more abundant. Vadose channels, which may also intersect the cave sediments, are mainly filled with "pedogenic" material derived from the paleokarst surface. Immediately prior to marine transgression over the paleokarst surface, some cavities were filled with marine-derived microturbidites. In general, the diversity of cave fills and the amount of surface material decrease with distance from the paleokarst surface. Below the paleokarst surface, the δ13C and δ18O values of a host rock and cavity deposits show good correlation with trends significant for meteoric diagenesis. It is shown that deposits associated with phreatic caves can be of great importance for the study of the speleogenetic, geomorphological and hydrogeological evolution of certain palaeokarst regions.

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