Sediment transport

Human activities over the past 200 years have fundamentally transformed the shape of Australia’s southern Murray Darling Basin (SMDB). The arrival of British colonists in the 19th century disrupted millennia of human management of the region and brought widespread changes to biota and soils. The subsequent development of mining, transport and irrigation infrastructure re-engineered the region’s landscapes to meet human objectives and ambitions. This paper offers an integrated regional history of anthropogenic change across the SMDB, identifying historical processes driving complex ongoing interactions between human activities and the natural environment. We examine three broad domains of engineering and geo-disturbance in the region, including the development of transport corridors, micro and macro-scale water management, and landforms remade by erosion and sedimentation. We use the archaeology of the recent past to integrate insights drawn from physical geography, fluvial geomorphology and related research into the enduring landscape changes of modern Australia’s food bowl.

Excel spreadsheet Settling Velocity.xls (2.1) calculates the terminal settling velocity of single spherical particles and of single natural sediment particles, in liquids and gases. It also predicts the hindered settling velocity of concentrated suspensions, by using Richardson & Zaki’s Law.
Guo (2002), Song Zhiyao et al. (2008), and Cheng (2009) combined the 3 “classical” settling velocity equations on laminar flow (Stokes’ Law), intermediate flow, and turbulent flow (Newton’s Law) each to only one relatively simple “new” settling velocity equation, used in this spreadsheet.
Calculations by these new settling laws are compared and contrasted with the sometimes tedious
classical calculations, and validated by graphical and manual sedimentation calculations.
13 worked examples illustrate how to use this spreadsheet, and how do manual calculations.

The local scour around bridge piers is one of the most common causes of bridge failures. Many equations have been proposed for determination. Most of these equations have a reliability and are used for design, were developed when the pier located within straight reaches for both flume and field studies. However, few studies have been conducted on bridge pier located within the curved channel. A laboratory work was conducted to measure the local scour which is formed around single circular pier fixed at each 30 o of the bend while adopting three different diameters. The results show that the maximum depth of scour and the maximum extents (i.e., length and width) of scour hole, and maximum modification factor due to bend have occurred when the pier is located at sector 90 o of the bend. The results also show that the diameter has a significant effect on scour phenomenon.

Sediment transport is a prevalent vital process in uvial and coastal environments, and \incipient motion" is an issue inseparably bound to this topic. This study utilizes a novel hybrid method based on Group Method of Data Handling (GMDH) and Genetic Algorithm (GA) to design GMDH structural (GMDH-GA). Also, Singular Value Decomposition (SVD) was utilized to compute the linear coeecient vectors. In order to predict the densimetric Froude number (Fr), the ratio of median diameter of particle size to hydraulic radius (d=R) and the ratio of sediment deposit thickness to hydraulic radius (t s =R) are utilized as eeective parameters. Using three diierent sources of experimental data and GMDH-GA model, a new equation is proposed to predict incipient motion. The performance of development equation is compared using GMDH-GA and traditional equations. The results indicate that the presented equation is more accurate (RMSE = 0:18 and MAP E = 6:48%) than traditional methods. Also, a sensitivity analysis is presented to study the performance of each input combination in predicting incipient motion.

Saltation is the dominant mode of the sediment transport in rivers. Several factors such as the viscosity of the carrier liquid, size of the moving particles, the roughness of the river bed, initial conditions of the numerical procedure (i.e. lift-off angles and velocities, and initial angular velocity), and the accuracy of the empirical features of the governing equations (e.g. drag and lift coefficients) have sig¬ nificant effects on the accuracy of the numerical simulation of the sediment particle saltation. Numerous studies were considered various aspects of the numerical simulation of the sediment saltation, although no significant research has been conducted on how the simultaneous variations of the parameters of the model affect the accuracy of the simulation results. Therefore, in the present study, a systematic sensitivity analysis of some of the aforementioned input factors was performed through executing over 1,000 numer¬ ical experiments for single-step saltation. An accurate particle saltation model was developed for the range of sand to gravel in the Lagrangian approach. The model, which was verified using available experimental data, includes the non-linear drag force, the shear lift force, Magnus force, the buoyancy force, the added mass force, the history force and torque. The results indicated that the rankings of the importance of the input parameter errors on the output results for sand grain are: the viscosity of the carrier liquid, lift-off angle and velocity, the roughness of the river bed and initial angular velocity, whereas this rankings for gravel grain are: the roughness of the river bed, lift-off angle, initial angular velocity, lift-off velocity and the viscosity of the carrier liquid.

Soil organic carbon (OC) mobilization due to erosional processes can have consequences regarding CO2 emission or sequestration. OC can be mineralized (emitted as CO2 to the atmosphere) during detachment, transport and deposition of soil particles, or buried in depositional settings, where it can also be stabilized. The contradicting results in the published literature in the last decade point towards a lack of information concerning OC dynamics in relation to different erosion processes at different spatial scales. The objective of this work was to characterize the quantity and type of erosion OC mobilized by the different erosion processes identified at a catchment scale with respect to the original soils where they came from. With the purpose of analysing the type (labile or stable) and quantity of organic carbon (OC) mobilized by different erosive processes identified at the slope-bed connection, the erosion deposits of gullies, sheet erosion, bank erosion and tillage erosion wer...

1st International Conference on Managing Rivers in the 21st Century: Issues & Challenges ... River Restoration Through Bank Stabilization Using FLUVIAL-12: Case Study of Raia River, Ipoh, Perak ... AHMAD DARUS, River Engineering Section, Department of Irrigation and ...

An Adaptive Management Framework (AMF) is a systematic process for continually improving management policies and practices by learning from the outcomes of operations through research. There are many benefits to an adaptive management framework as it allows for decision making to proceed even when there are considerable gaps in knowledge and uncertainty, by specifying actions, monitoring and adjustment of visions,

The Cávado estuary inlet is situated in the coastal zone of Esposende (NW Portugal) where sandy beaches have migrated inland and thinned, and cliffs have retreated rapidly over the last years. The coastal zone of Esposende extends over 15 km from the Neiva River until Apúlia. The coastal segment of Esposende can be considered of mixed energy and wave-dominated type, according to DAVIS and HAYES (1984). The local tide is mesotidal and semidiurnal, with a maximum equinoctial spring tide high-water level of 3.9 m, a minimum low-water level of 0.2 m, and a mean spring tide of 3.49m (data from Instituto Hidrográfico da Marinha). The inlet is a natural feature of the Cávado estuary, subject to silting up, and enclosed between a breakwater on the northern side and the end of a migrant sandy spit on the southern side. Recently, it was suggested that the best option for decreasing silting-up and increasing navigability, would be to build two breakwaters and artificially manage the inlet. Thi...

Human intervention in the hydrologic basin of the Colorado River has eliminated water discharge and sediment supply to the river's mouth and its delta. After ∼95 years of applying strong flow control policies, the previous sedimentary budget in the delta has changed, the delta now being entirely exposed to the hydrodynamic forces in its basin. In order to assess the anthropogenic impact of water diversion on deltaic sedimentary processes and short-term delta geomorphic evolution, textural and mineralogical analyses were performed on 68 sediment samples collected from the river, estuary, beach, continental shelf, delta plain and desert. The results show a consistent NE to SW textural gradient on the shallow-marine platform adjacent to the Colorado River delta (an area known as the Upper Gulf of California), and a net cross-basinal sediment transport occurring in the same direction. Two opposing littoral transport components exist along the Sonoran and Baja Californian coasts: (1) net sediment transport from SE to NW along the Sonoran coast delivers sediments from the ocean into the estuarine basin through the Sonora channel of the deltaic system of the Colorado River; and (2) sediment transport from N to S along the Baja Californian coast removes sediments from the estuarine basin of the Colorado River into the Northern Gulf of California (NGC). The residual sediment transport pattern observed suggests a counterclockwise path of exchange of materials between the estuarine basin of the Colorado River and the NGC. Multivariate cluster and factor analyses of the heavy-mineral data reveal the existence of a sedimentary system dominated by two end-members, representing two heavy-mineral sedimentary provinces: (1) the Sonora province is characterized by a heavy-mineral suite of garnet and zircon (G–Z), whose sediment supply originates from the sandy sediments of the Sonora Mesa deposits and Sonora's Gran Desierto; and (2) the Baja California province is characterized by a hornblende–epidote–pyroxene (H–E–P) suite, whose sediments originate from the earlier supply of the Colorado River. Since the Colorado River is no longer supplying sediments from its drainage basin, the H–E–P-rich sediments now actively dispersed in the system have mainly originated through intense reworking of the delta. Moreover, G–Z-rich sediments are starting to invade areas previously dominated by H–E–P sediments. On the basis of the prevailing hydraulic regime, textural and mineralogical characteristics of the sediments, and hydrographic and bathymetric information from the region, a hypothetical sediment dynamics model for the delta region is proposed, in which the tidally influenced, wave-dominated, sediment-reworked, slightly eroding Sonoran coast changes into a tide-dominated, depositional, very slowly prograding Baja Californian coast. This study shows that human intervention of the hydrologic basin of the Colorado River is not only responsible for inducing drastic hydrologic changes in its estuary (i.e., from brackish to hypersaline), but also for inducing drastic changes in the hydrographic circulation of the receiving basin (i.e., from long-basinal to cross-basinal). These changes are ultimately responsible for the relocation of massive volumes of the delta's sediment inventory, and for the serious ecological impact of habitat loss of indigenous species, such as the now endangered Totoaba (Totoaba macdonaldi) and Vaquita (Phocoena sinus).

The paper presents the case of the Boljunčica reservoir, which began operation in 1973. It is situated on the Istria peninsula (Croatia). This is a multipurpose reservoir which was built in order to protect the downstream area from flood, to store water for irrigation, and to control sediment transport. The reservoir is situated on the contact zone between water impermeable

The buildup of sediment deposits in reservoirs is a long-standing problem with serious consequences on the reservoirs' functionality and the ecology of their river systems. In the last two decades, hydraulic dredging has been used as a more viable engineering solution to restore reservoirs' sustainability. This study proposes a novel ejector-pump dredging system (EPDS) that solely utilizes hydraulic dredging for removal and transport of the sediments deposited at the reservoir's bed. Unlike conventional dredging methods, air is injected into the header pipeline to create a turbulent three-phase flow regime that enhances the solids suspension and continuous flow in the system. Introducing air effectively reduces the critical value of the deposition velocity of the dredged solids and transports them in a slug flow regime. This technique minimizes the tendency of the sediment to settle, and therefore eliminates system plugging. A laboratory prototype of the proposed system has proven the efficacy of removal and transport of mixed-size sediments up to 150 mm. Field trials have further shown the feasibility of the proposed system. Removal of large sediments with productivity approaching 70 m 3 =h was made possible using the suction-type EPDS. The hopper-type EPDS enabled carrying the dredged material for up to 1,000 m without resorting to a booster pump. The developed system was successfully used as part of an integrated dredging management program carried out for the Oouchibaru, Saigo, and Yamasubaru dams in the Mimi River basin, Japan. The very low turbidity levels recorded during the sediment dredging and transport operations of EPDS are indicative of the eco-friendly performance of the system.