Understanding Of Sedimentation Processes Research Articles

Determination of sediment conditions of the Jurassic deposits of the Akkuduk field based on the analysis of ichnofossils

In this paper were presented the results of the lithological-sedimentological description of the core material of the Middle-Upper Jurassic deposits with additional study of the vital activity traces of organisms in Akkuduk field to determine the environmental condition and identification of facies. The Akkuduk field is characterized by a rather complicated environmental conditions and understanding of sedimentation processes. In the course of the work, 9 main ichnogenus were identified in the core samples that make up the section of the field, which contain numerous traces of the vital activity of organisms that do not differ in diversity. Associations were determined to identify facies in the section and their dependence on trace fossils. The generalization of the obtained materials enabled to build columns with the definition of facies and envionmental conditions, which subsequently can be used for conducting facies modeling in the geological model of the field. Keywords: lithology; sedimentology; ichnofossils; traces fossils; ichnofacies; facies.

Global Observations of Riverbank Erosion and Accretion From Landsat Imagery

AbstractRiverbank migration has historically been seen as a risk to infrastructure that can be combated through channelization, bank stabilization, and sediment trapping. The physical processes involved with riverbank erosion and deposition are well defined, yet the solutions to equations that describe these processes are computationally and data intensive over large domains. While current understanding of large‐scale river channel mobility largely comes from reach‐ and watershed‐scale observations, we need global observations of riverbank erosion and accretion to broaden our understanding of sediment processes within and across river basins. In this work, we create the first global data set of riverbank erosion for >370,000 km of large rivers using up to 20 years of water classifications from Landsat imagery. We estimate uncertainty by propagating water classification errors through our methods. Globally, we find riverbank erosion for rivers wider than 150 m to have an approximately log‐normal distribution with a median value of 1.52 m/yr. Comparing our data set to 25 similar estimates of riverbank migration, we found a normalized mean absolute error of 42% and a bias of 5.8%. We show that river width is the best first‐order predictor of riverbank erosion, in agreement with existing literature. We also show that the relationship between width and bank erosion is substantially different among a sample of global river basins and suggest that this is due to second‐order influences of geology, hydrology, and human influence. These data will help improve models of sediment transport, support models of bank erosion, and improve our understanding of human modification of rivers.

Integrating Sediment (dis)Connectivity into a Sediment Yield Model for Semi-Arid Catchments

Soil erosion-associated sedimentation has become a significant global threat to sustainable land and water resources management. Semi-arid regions that characterise much of southern Africa are particularly at risk due to extreme hydrological regimes and sparse vegetative cover. This study aims to address the need for an erosion and sediment delivery model that successfully incorporates our conceptual understanding of sedimentation processes in semi-arid regions, particularly sediment storage and connectivity within a catchment. Priorities of the Semi-arid Sediment Yield Model (SASYM) were simplicity and practical applicability for land and water resource management while adhering to basic geomorphic and hydrological principles. SASYM was able to represent multiple sediment storages within a catchment to effectively represent a change in landscape connectivity over geomorphic timeframes. SASYM used the Pitman rainfall–runoff model disaggregated to a daily timescale, the Modified Universal Soil Loss Equation (MUSLE), incorporating probability function theory and a representation of sediment storages and connectors across a semi-distributed catchment. SASYM was applied to a catchment in the Karoo, South Africa. Although there were limited observed data, there was a historical dataset available for the catchment through dam sedimentation history. SASYM was able to effectively present this history and provide evidence for landscape connectivity change.

Complex sedimentary processes in large coastal embayments and their potential for coastal morphological and paleo tropical cyclone studies: A case study from Choctawhatchee Bay Western Florida, U.S.A

Storminess and sea-level can both have a significant impact on landforms in cyclone-prone coastal regions, although much of our understanding comes from short-timescale modern observations. This study aims to understand the variability of sediment transport and deposition in the Choctawhatchee Bay/Santa Rosa Island in the northern Gulf of Mexico, establishing the dominant sediment transport processes and morphological response of the barrier system to long-term variations in storminess and rising sea-levels.Here, we study the spatial and temporal changes in physicochemical properties of the sedimentary record of Choctawhatchee Bay to examine the character and fidelity of records of storm impacts spanning the Holocene. Proxies for marine and terrestrial conditions in the cores situated closer to the present barrier (proximal) show that sedimentation in coastal areas and marine influence of the bay during the last ~8000 yrs. were mainly determined by barrier response to the Holocene transgression and changes in storminess. In contrast, sedimentation close to the landward shore was governed by terrigenous input. The correlation of grain size and terrigenous proxies with regional hurricane records indicates that hinterland erosion by the rainfall during hurricane events is likely the dominant terrigenous sediment transport mechanism in areas close to the landward shore of the bay. These results suggest that sediment archives in large coastal deposition environments are equally suitable for sea level and cyclone modulated coastal morphological studies and paleo tropical cyclone studies, depending on the location, selected with an understanding of sedimentation processes in the vicinity.

A field-based technique for sediment incubation experiments

Sediment incubation experiments have been a cornerstone in limnology for improving our understanding of sediment processes in aquatic ecosystems. Experiments are usually performed in the laboratory, which has several limitations, including: additional handling that may disturb the integrity of the sediments, the financial expense of purchasing and maintaining growth chambers and anaerobic gloveboxes, and the inability to exactly recreate the ambient environmental conditions experienced by sediments in natural ecosystems. Furthermore, laboratory-based techniques are simply not possible with flocculent sediments from eutrophic ecosystems that are highly prone to separation following changes in pressure. Here, we describe a field-based technique for incubating sediment cores that is simple, versatile, and inexpensive. Our in situ incubation technique is highly effective for exposing sediments to natural temperature, pressure, and light regimes, and easily maintaining sediments under anaerobic conditions.

Review of Sedimentation Engineering—Processes, Measurements, Modeling, and Practice (ASCE Manuals and Reports on Engineering Practice No. 110) by Marcelo H. GarciaSedimentation Engineering—Processes, Measurements, Modeling, and Practice (ASCE Manuals and Reports on Engineering Practice No. 110)ASCE9780784408148$138.75

Sedimentation engineering is a very important subject that deals with sedimentation processes such as erosion, entrainment, transport, deposition, and compaction of sediment induced by water, wind, gravity, and ice and affected by human activities. The original ASCE Manual 54 Sedimentation Engineering, edited by Vito A. Vanoni 1975 and the ASCE Task Committee for the Preparation of a Manual on Sedimentation assembled state-ofthe-art information and knowledge on sedimentation engineering available at that time. Since then, the scientific and engineering understanding and knowledge of sedimentation processes have been greatly advanced and expanded. The recently published Manual 110, edited by Marcelo H. Garcia and his task team, updates selected topics in the original manual and presents recent advances and new topics in the field of sedimentation science and engineering as a complement to the original Manual 54. This update is timely and makes significant contributions to the literature. This comprehensive volume consists of 23 chapters and 6 appendices. Among them, Chapters 2–4 broadly cover fundamentals of sediment transport mechanics, and a section of Chapter 19 briefly presents the mechanics of hyperconcentrated sediment flows. The original Manual 54 gives a good understanding of sedimentation processes and well defines the scope of sediment transport mechanics, whereas the new volume presents in considerable detail many recently developed theories and methods for non-cohesive sediment transport in sand-bedded streams Chapter 2 and gravel-bedded streams Chapter 3 , as well as for cohesive sediment transport Chapter 4 . Chapter 2 also introduces turbidity currents, while Chapter 3 also presents the transport of multiple-sized nonuniform sediment mixtures, which has been extensively studied in the last three decades. Chapter 4 explains the effects of waves on cohesive sediment transport, but such effects on noncohesive sediment transport are omitted in this manual. Chapter 5 reviews technologies for measuring bed-material properties and suspended and bed-load discharges, while Appendix D describes methods for estimating sediment discharges in streams using direct measurement data and empirical relations developed between hydraulic parameters and sediment transport potential. Several new types of samplers are introduced, as well as some traditional ones developed in the mid-twentieth century but modified recently. The measurement of bed load

Acoustic instrumentation for measuring near-bed sediment processes and hydrodynamics

Improved understanding and modelling of interactions between biological and physical processes has required progress in the understanding of sediment processes and their relationship to bedforms, hydrodynamics and benthic biology. Recently, simultaneous, co-located in situ measurements of suspended sediments, near-bed velocities and bed morphology have been made possible using new acoustic instruments, including a triple frequency acoustic backscatter system, (ABS); a uniaxial, and triple axis, coherent Doppler velocity profiler, (CDVP); a sand ripple imager (SRI); and a sand ripple profiler (SRP). Together these instruments measure the relevant hydrodynamic and sediment parameters necessary to investigate sediment processes in the bottom metre above the bed, with centimetric resolution. The range of data from such instruments is required to fully understand the related processes occurring near the seabed. The outcome of such measurements should improve our understanding of benthic processes in general.

Geotechnical and sedimentological investigations of deep-sea sediments from a manganese nodule field of the Peru Basin

Abstract Deep-sea mining of manganese nodules will significantly modify the surface layer of deep sea. Surface sediments are mechanically disturbed, and a cloud of sediment particles suspended and re-deposited. Assessment of sedimentological and soil mechanical characteristics of undisturbed top layer sediments from a manganese nodule field of the Peru Basin are necessary to provide baseline data for soil mechanical estimations and for the physical and numerical modelling of environmental impacts of future ocean mining activities. This will assist the International Seabed Authority to make decisions on how to formulate the mining code, and will increase our understanding of sedimentation processes in the Peru Basin. The deployment of a new sampling device (maxicorer) guaranteed undisturbed sediment samples in which soil mechanics-related parameters were measured including sediment density, water content, shear strength, and penetration force. Data evaluation show a close relationship between the soil mechanical parameters and various sedimentological properties such as grain-size distribution, mineral composition and micro-structure. From the results it can be concluded that in the worst case a deep-sea nodule mining vehicle would sink about 15–20 cm into the sea bed.