Quantity Of Sediment Transport Research Articles

Flash rip current driven suspended sediment flushing amplification in depth-integrated modeling framework

Until recently, wave and hydrodynamic properties in the cross-shore direction have been linked to accretive or erosive morphological evolution. However, various uncertainties remain, hindering the full understanding and accurate prediction of the transport direction and quantity of sediment transport in nearshore areas. In this study, we showed that flash rip currents (FRCs) could significantly amplify suspended sediment flushing out of the surf zone by greatly increasing advective flux, even under accretive wave conditions in a depth-integrated modeling framework. Compared to the case without FRCs, where only one-dimensional cross-shore direction waves and currents exist, FRC-driven seaward advective sediment flux increased by approximately O(102) times under normal incoming waves on alongshore uniform beaches, at least for the tested wave and bathymetry conditions. To properly consider the role of FRCs in suspended sediment flushing, short wave related physics, such as nonhydrostatic pressure and frequency dispersion, had to be included. In addition, it was important to accurately predict not only wave properties but also local hydrodynamics that cause erosion and advection. Finally, uniform sandbars prevented beach erosion, even when FRCs occurred on uniform beaches, by dissipating the wave energy closely associated with FRC generation. Therefore, one-dimensional cross-shore direction approaches neglecting the role of FRC-driven sediment transport processes, which are closely related to short wave motions and occur in two-dimensional space, could lead to lower prediction accuracy.

ANALISIS ANGKUTAN SEDIMEN DASAR (BED LOAD) PADA SALURAN IRIGASI MATARAM YOGYAKARTA

In the last decade, the problem that has occurred in the Yogyakarta Mataram irrigation channel is the occurrence of sedimentation in the channel. This has an impact on reducing the cross-sectional discharge capacity of the canal and resulting in the supply of irrigation discharge to agricultural areas to be not optimal, so that agricultural productivity in the Mataram Irrigation Area will also not be optimal. The sediment transport (bed load) that occurs in an open channel can be approached using the empirical equation, including the Einstein, Meyer - Peter Muller and Frijlink equations. Sediment transport events that occur in the channel are stated based on the magnitude of the flow shear stress which exceeds the critical shear stress of the sediment particles. The quantity of sediment transport in the channel is stated on the logarithmic curve of the relationship between the froude number (fr) to the sediment transports (qb). The Curve explains that the increase in the froude number (fr) that occurs on each section of the channel will be directly proportional to the increase in the quantity of transport sediment (qb). The largest sediment transport occurred at the site of the Gambang and Nambongan channel section with a prediction of sediment transport of 3.57 m3/day and 3.67 m3/day, respectively. Thus, the potential for sediment transport that will settle in the downstream area is 3.67 m3/day.

Towards continuous long-term measurements of suspended particulate matter (SPM) in turbid coastal waters

The dynamics of sediment transport in the East Frisian Wadden Sea are important for the coastal zone and for ecosystem functioning. The tidal inlets between the East Frisian islands connect the back-barrier intertidal flats to the North Sea. Here, concentrations of suspended particulate matter (SPM) in the water column are highly variable, depending on weather conditions and tides. In order to estimate the nature and quantity of sediment transport, in situ measurements were carried out at a Time Series Station in the tidal inlet between the islands of Spiekeroog and Langeoog. This study shows the suitability of multispectral transmissometry (MST) for obtaining long-term SPM measurements with high resolution. The comparability of this technique to the standard filter method and the laser diffraction method [laser in situ scattering and transmissometry (LISST)] is demonstrated. In addition, the Junge coefficients derived from both MST and LISST measurements are compared. A time series of SPM data covering nearly 4 months is presented. As a major result, the data reveal that a single storm surge can have less impact on SPM dynamics than longer-lasting gales. This high-resolution long-term data set is very valuable for modelling suspended matter flux. It also provides background information for studying the influence of SPM dynamics on coastal sediments.

Hydrological controls of erosion and sediment transport in volcanic torrents

Abstract Sediment is transported in the form of debris flows in major gullies dissecting permeable volcanic slopes as exemplified by the Kami-kamihori Valley in the northern Japan Alps. Four years of hydrological observations in the headwater area of the gully showed that the surface runoff which triggers debris flows is related to peak 10- to 20-minute rainfall. Sediment production in such a short time is not sufficient to prepare a debris flow. Therefore, debris must have been accumulated at a particular section by repeated sediment discharge due to minor rainstorms. The volume of the debris produced in the headwaters was evaluated and correlated to an effective rainfall. The quantity of sediment transport at seven sections along the gully by debris flows in three periods was evaluated through the measurement of the topographic changes. It was compared with the total effective rainfall for the pertinent period, and the mean “sediment concentration” in the debris flow was calculated for each section and ...