International Journal of Sediment Research
Volume 33, Issue 1
Pages 1-92 (March 2018)
Introduction to the special issue of the 13th International Symposium on River Sedimentation, Stuttgart, Germany: Experimental and measuring/monitoring research related to sediment issues
Pages 1-2
Markus Noack, Heide Friedrich, Jochen Aberle
In-situ investigation on real-time suspended sediment measurement techniques: Turbidimetry, acoustic attenuation, laser diffraction (LISST) and vibrating tube densimetry
Pages 3-17
David Felix, Ismail Albayrak, Robert Michael Boes
Sensitivity analysis of sediment flux derived by laser diffraction and acoustic backscatter within a reservoir
Pages 18-26
Stefan Haun, Laura Lizano
Near-bankfull floods in an Alpine stream: Effects on the sediment mobility and bedload magnitude
Pages 27-34
Riccardo Rainato, Luca Mao, Lorenzo Picco
Application of an impact plate – Bedload transport measuring system for high-speed flows
Pages 35-46
Takahiro Koshiba, Christian Auel, Daizo Tsutsumi, Sameh A. Kantoush, Tetsuya Sumi
Experimental investigation on cohesionless sandy bank failure resulting from water level rising
Pages 47-56
Ryosuke Arai, Kazuyuki Ota, Takahiro Sato, Yasushi Toyoda
Erosion pattern of artificial gravel deposits
Pages 57-67
Fabian Friedl, Volker Weitbrecht, Robert M. Boes
Influence of reversing currents on the erosion stability and bed degradation of widely graded grain material
Pages 68-83
Alexander Schendel, Nils Goseberg, Torsten Schlurmann
On the way to airborne gravelometry based on 3D spatial data derived from images
Pages 84-92
M. Detert, L. Kadinski, V. Weitbrecht
Full papers are available at ScienceDirect:
https://www.sciencedirect.com/journal/international-journal-of-sediment-research .
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Markus Noack, Heide Friedrich, Jochen Aberle,
Introduction to the special issue of the 13th International Symposium on River Sedimentation, Stuttgart, Germany: Experimental and measuring/monitoring research related to sediment issues,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 1-2,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2018.02.002.
(http://www.sciencedirect.com/science/article/pii/S1001627918300453)
David Felix, Ismail Albayrak, Robert Michael Boes,
In-situ investigation on real-time suspended sediment measurement techniques: Turbidimetry, acoustic attenuation, laser diffraction (LISST) and vibrating tube densimetry,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 3-17,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2017.11.003.
(http://www.sciencedirect.com/science/article/pii/S100162791730375X)
Abstract: Real-time measurements of Suspended Sediment mass Concentration (SSC) and Particle Size Distribution (PSD) are of prime importance for the investigation and management of fine-sediment related processes in surface water systems and hydraulic schemes. In a field study at the waterway of the hydropower plant (HPP) Fieschertal in the Swiss Alps, the real-time measurement performance of the following techniques and instruments were assessed based on measurements in the sediment seasons of the years 2013 and 2014: (1) turbidimetry, (2) single-frequency acoustic attenuation using a standard acoustic discharge measurement (ADM) installation, (3) laser diffraction (Laser In-Situ Scattering and Transmissometry, LISST), and (4) vibrating tube densimetry using a Coriolis Flow and Density Meter (CFDM). Reference SSCs were obtained from gravimetric analysis of 219 automatically pumped water samples. LISST additionally supplied PSD every minute. The median particle diameter, d50, was usually 15µm and increased occasionally to 100µm. The turbidimeter and the ADM underestimated the SSC when the transported particles were coarser than usual. Such temporary biases resulted from the poor correlation between d50 and SSC at this study site. The SSCs from CFDM and LISST were not or less biased by PSD variations. Mainly due to angular and flaky particle shapes, SSC from LISST needed a correction by 79% on average. With the usually prevailing silt particles, an optical path length of 5mm and no dilution, the SSC measurement range of LISST was limited to about 1.5g/l. The CFDM allowed measuring higher SSC than the other investigated instruments (e.g. up to 13.5g/l). With a periodic offset correction, its relative SSC measurement uncertainty was < 20% for SSC ≥ 1.5g/l. To reliably measure a wide range of SSC with temporarily variable PSD, a combination of instruments is recommended: e.g. a standard LISST, a CFDM, and an automatic water sampler for gravimetric reference measurements.
Keywords: Suspended sediment concentration; Turbidity; Acoustic attenuation; Laser diffraction; Coriolis flow and density meter; Gravimetric analysis
Stefan Haun, Laura Lizano,
Sensitivity analysis of sediment flux derived by laser diffraction and acoustic backscatter within a reservoir,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 18-26,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2018.01.001.
(http://www.sciencedirect.com/science/article/pii/S1001627918300143)
Abstract: A combination of two indirect methods to measure sediment flux is presented in this study to evaluate suspended sediment transport in a hydropower reservoir. The acoustic backscatter signal (ABS) from an Acoustic Doppler Current Profiler (ADCP) is therefore applied in pre-defined transects within the reservoir in combination with a Laser In-Situ Scattering Transmissometry – stream lined device (LISST-SL). The stationary LISST-SL derived suspended sediment concentration (SSC) measurements are used to calibrate the ABS. From the LISST-SL measurements a time series of SSC is obtained. This enables, in addition, a comprehensive data analysis to evaluate the influence of natural fluctuations of the SSC on the calculated sediment flux, which should be taken into account when assessing sediment transport. Furthermore SSC measurements are done with the LISST-SL close to the reservoir bed. In areas close to the bed no information regarding the ABS is available from the ADCP measurements due to the side-lobe interference. In various studies the information from the last three valid cells is used for extrapolation. However, as result of a comparison of the LISST-SL measurements with extrapolated SSC values from the ADCP measurements it can be seen that, especially in deep reservoirs, this method has to be adapted to the in-situ conditions.
Keywords: Reservoir; Suspended sediment concentrations; Sediment flux; Laser diffraction; Acoustic backscatter signal
Riccardo Rainato, Luca Mao, Lorenzo Picco,
Near-bankfull floods in an Alpine stream: Effects on the sediment mobility and bedload magnitude,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 27-34,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2017.03.006.
(http://www.sciencedirect.com/science/article/pii/S1001627917300914)
Abstract: In a mountain environment, the transport of coarse material is a key factor for many fields such as geomorphology, ecology, hazard assessment, and reservoir management. Despite this, there have been only a few field investigations of bedload, in particular using multiple monitoring methods. In this sense, attention has frequently focused on the effects of “high magnitude/low frequency floods” rather than on “ordinary events”. This study aims to analyze the sediment dynamics triggered by three high-frequency floods (recurrence interval “RI” between 1.1 and 1.7yr) that occurred in the Rio Cordon basin during 2014. The flood events were investigated in terms of both sediment mobility and bedload magnitude. The Rio Cordon is an Alpine basin located in northeastern Italy. The catchment has a surface area of 5km2, ranging between 1763 and 2763m above sea level. The Rio Cordon flows on an armored streambed layer, with a stable step-pool configuration and large boulders. Since 1986, the basin has been equipped with a permanent station to continuously monitor water discharge and sediment flux. To investigate sediment mobility, 250 PIT-tags were installed in the streambed in 2012. The 2014 floods showed a clear difference in terms of tracer displacement. The near-bankfull events showed equal mobility conditions, with mean travel distance one order of magnitude higher than the below-bankfull event. Furthermore, only the near-bankfull events transported coarse material to the monitoring station. Both events had a peak discharge up to 2.06m3s-1, but the bedload transport rates differed by more than one order of magnitude, proving that under the current supply-limited condition, the bedload appears more related to the sediment supply than to the magnitude of the hydrological features. In this sense, the results demonstrated that near-bankfull events can mobilize large amounts of material for long distances, and that floods of apparently similar magnitude may lead to different sediment dynamics, depending on the type and amount of sediment supply.
Keywords: Bedload; Alpine basin; Sediment dynamics; Bedload tracing; PIT-tags
Takahiro Koshiba, Christian Auel, Daizo Tsutsumi, Sameh A. Kantoush, Tetsuya Sumi,
Application of an impact plate – Bedload transport measuring system for high-speed flows,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 35-46,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2017.12.003.
(http://www.sciencedirect.com/science/article/pii/S1001627917304122)
Abstract: To achieve the sustainable use of dams, the development of methods for sediment management in reservoirs is required. One such method includes the use of Sediment Bypass Tunnels (SBTs) to divert sediment around a dam, thereby preventing sedimentation in the reservoir. However, SBTs are prone to severe invert abrasion caused by the high sediment flux. Therefore, it is necessary to establish a measurement system of the sediment transport rate in these tunnels. One system to measure sediment transport in rivers is the Swiss plate geophone, which can register plate vibrations caused by particle impact. In Japan, the Japanese pipe microphone is used, and sediment transport is measured based on the sound emitted by the particle impact. In this study an attempt was made to optimize the advantages of both systems by fixing a microphone and an acceleration sensor to a steel plate. The results of calibration experiments with this new system are presented and compared with the existing methods. It was found that the acceleration sensor can detect sediment particles larger than 2mm in diameter. Moreover, a new parameter, referred to as the detection rate, was introduced to describe the correlation between the actual amount of sediment and the registered output. Finally, two parameters - the saturation rate and hit rate - are introduced and exhibit strong correlation with the detection rate.
Keywords: Sediment Bypass Tunnel; Bedload; Acoustic measurement; Geophone; Hydrophone; High-speed flow
Ryosuke Arai, Kazuyuki Ota, Takahiro Sato, Yasushi Toyoda,
Experimental investigation on cohesionless sandy bank failure resulting from water level rising,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 47-56,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2017.08.002.
(http://www.sciencedirect.com/science/article/pii/S1001627917302640)
Abstract: In the last decade, sediment replenishment forming cohesionless sandy banks below dams has become an increasingly common practice in Japan to compensate for sediment deficits downstream. The erosion process of the placed cohesionless sediment is a combination of lateral toe-erosion and the following mass failure. To explore cohesionless bank failure mechanisms, a series of experiments was done in a soil tank using a compacted sandy soil mass exposed to an increasing water level. Two types of uniform sand (D50 = 0.40mm and 0.17mm) and two bank heights (50cm and 25cm) were used under the condition of a constant bank slope of 75°. The three dimensional (3D) geometry of the bank after failure was measured using a handheld 3D scanner. The motion of bank failure was captured using the particle image velocimetry (PIV) technique, and the matric suction was measured by tensiometers. The compacted sandy soil was eroded by loss of matric suction accompanying the rise in water level which subsequently caused rotational slide and cantilever toppling failure due to destabilization of the bank. The effect of erosion protection resulting from the slumped blocks after these failures is discussed in the light of different failure mechanisms. Tensile strength is analyzed by inverse calculation of cantilever toppling failure events. The tensile strength had non-linear relation with degree of saturation and showed a peak. The findings of the study show that it is important to incorporate the non-linear relation of tensile strength into stability analysis of cantilever toppling failure and prediction of tension crack depth within unsaturated cohesionless banks.
Keywords: Riverbank erosion; Matric suction; Cohesionless bank; Tensile strength
Fabian Friedl, Volker Weitbrecht, Robert M. Boes,
Erosion pattern of artificial gravel deposits,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 57-67,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2017.08.003.
(http://www.sciencedirect.com/science/article/pii/S1001627917302743)
Abstract: Sediment replenishment with artificial gravel deposits is an option to compensate for sediment deficits in rivers and to improve their ecological conditions. Predicting and quantifying the erosion rate of an artificial gravel deposit is important to successfully perform river restoration projects. Laboratory experiments have been done to investigate the influence of various parameters on the erosion pattern of artificial gravel deposits. In the present paper the effects of deposit geometry, bulk density, grain size distribution, and hydraulic load on the erosion process are described. The temporal evolution of the deposit geometry and the corresponding mean erosion rates were studied. The mean erosion rate increases with deposit height, deposit width, and decreasing grain size. Furthermore, no significant impact of the bulk density was observed. Equations to predict the mean erosion rate are proposed. This investigation helps to determine the design frequency of gravel dumping and deposit volumes for restoration projects.
Keywords: Artificial gravel deposits; Bed load transport; Laboratory experiments; Sediment replenishment
Alexander Schendel, Nils Goseberg, Torsten Schlurmann,
Influence of reversing currents on the erosion stability and bed degradation of widely graded grain material,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 68-83,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2017.07.002.
(http://www.sciencedirect.com/science/article/pii/S1001627917302123)
Abstract: Physical model tests were done in a recirculating flume to investigate the overall erosion stability of widely graded bed material in estuarine and coastal conditions by means of simulating tidal flow conditions with reversing currents. As a result of the reversing flow conditions, previously protected sediment eventually became exposed again, leading to bidirectional displacement processes depending on the flow direction. Furthermore, eroded sediment fractions were slightly finer due to flow in the initially applied direction rather than under the subsequently applied flow in the reverse direction. This indicates higher critical shear stresses, and, thus, erosion stability for the initial flow direction. In comparison to the erosional pattern found when subjecting the material to unidirectional currents, this study finds an even higher erosional stability for sediment fractions smaller than the median (d50) diameter of the parent bed material under reversing current conditions. Overall, no significant damage or failure of the bed was observed after subjecting the material to reversing currents, indicating only a small amount of bed degradation, and, thus, high potential for scour and bed protection under the tested flow conditions.
Keywords: Scour protection; Laboratory tests; Erosion stability; Bed degradation; Reversing current; Widely graded bed material
M. Detert, L. Kadinski, V. Weitbrecht,
On the way to airborne gravelometry based on 3D spatial data derived from images,
International Journal of Sediment Research,
Volume 33, Issue 1,
2018,
Pages 84-92,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2018.02.001.
(http://www.sciencedirect.com/science/article/pii/S1001627918300350)
Abstract: This paper presents basic tests to develop an airborne photogrammetric methodology that derives grain size characteristics of gravel bed rivers. The data acquisition was done using a lightweight action cam and a hand-held digital single lens reflex camera. Image processing comprised the structure from motion technique and multiview-stereo algorithms to obtain digital elevation models of non-cohesive gravel beds. Laboratory results indicate that the method accuracy is about four to six times lower than laser-scan data when based on action cam data. The accuracy of digital elevation models computed via photos taken by the reflex camera is almost of the same range as the laser data. Field experiments were done to test the performance of image based gravelometry against manual surface sampling. For this application the action cam was mounted to a low-cost quadrocopter, while the reflex camera was operated by hand. Results indicate that this combination has a high potential to generate data from which characteristic grain size parameters can be estimated.
Keywords: Airborne photogrammetry; Grain size distribution; Gravel bed; Field work; Gravelometry; Image analysis; Laboratory experiments; Structure from motion; Surface sampling
