@article{HagemannAlbayrakBoesetal.2016, author = {Hagemann, M. and Albayrak, I. and Boes, R.M. and Auel, C. and Sumi, T.}, title = {Reviewing research and experience on sediment bypass tunnels}, series = {Int. Journal on Hydropower and Dams}, journal = {Int. Journal on Hydropower and Dams}, pages = {54 -- 58}, year = {2016}, language = {en} } @inproceedings{BoesHagemannMuellerAlbaryaketal.2018, author = {Boes, R.M. and Hagemann-M{\"u}ller, M. and Albaryak, I. and M{\"u}ller, B. and Caspescha, L. and Flepp, A. and Jacobs, F. and Auel, C.}, title = {Sediment bypass tunnels: Swiss experiences with bypass efficiency and abrasion-resistant invert materials}, series = {VINGT SIXI{\`E}ME CONGR{\`E}S DES GRANDS BARRAGES, Vienne, Juillet 2018}, booktitle = {VINGT SIXI{\`E}ME CONGR{\`E}S DES GRANDS BARRAGES, Vienne, Juillet 2018}, publisher = {COMMISSION INTERNATIONALE DES GRANDES BARRAGES}, doi = {10.25974/fhms-15139}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151399}, year = {2018}, abstract = {In this paper typical bypass efficiencies of sediment bypass tunnels (SBTs) used to counter reservoir sedimentation are described, distinguishing between two layouts of the tunnel intake. It results that SBTs are an effective measure to reduce the sedimentation of dam reservoirs, particularly of type (A) with intake at the reservoir head. The hydroabrasive wear of tunnel inverts is significant and has to be mitigated by using adequate invert liners. The invert abrasion can be estimated based on an abrasion model where a correct input value of the bed material resistance coefficient is paramount to limit model uncertainties. Based on abrasion measurements at prototype SBTs typical values of the material resistance coefficient are recommended for high-strength concrete, natural stones and steel liners. The field experiences gathered so far and the comparison of various invert materials suggest granite pavers as a promising lining material for severe abrasion conditions.}, language = {en} } @inproceedings{AuelSanjouOkamotoetal.2017, author = {Auel, C. and Sanjou, M. and Okamoto, T. and Kobayashi, S. and Sumi, T.}, title = {Mean flow and turbulence variation due to invert abrasion}, series = {Proc. 2nd Int. Workshop on Sediment Bypass Tunnels, FP15, Kyoto, Japan}, booktitle = {Proc. 2nd Int. Workshop on Sediment Bypass Tunnels, FP15, Kyoto, Japan}, publisher = {Kyoto University}, doi = {10.25974/fhms-15172}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151721}, year = {2017}, abstract = {Due to high bedload sediment transport, many sediment bypass tunnels (SBT) are prone to severe invert abrasion. However, there is little information about the flow characteristics in SBTs after invert abrasion initiated and progresses with time. In the present study, laboratory flume experiments were performed to investigate how the hydraulic conditions change after abrasion patterns developed on the invert. A typical invert abrasion pattern was produced using 3D-printing technique and implemented in the laboratory flume. Flow depths were measured to compare the initial with the abraded state. Furthermore, turbulence measurements using 2D-laser Doppler anemometry technique were performed to obtain the mean and turbulence flow characteristics. This paper describes results of these measurements focusing on the streamwise and vertical flow velocities, turbulence intensities and Reynolds shear stress.}, language = {en} } @inproceedings{AuelKantoushSumi2016, author = {Auel, C. and Kantoush, S.A. and Sumi, T.}, title = {Positive effects of reservoir sedimentation management on reservoir life: Examples from Japan}, series = {84th Annual Meeting of ICOLD, Johannesburg, South Africa 4-11-4-20.}, booktitle = {84th Annual Meeting of ICOLD, Johannesburg, South Africa 4-11-4-20.}, publisher = {ICOLD}, isbn = {978-0-620-71042-8}, doi = {10.25974/fhms-15149}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151498}, year = {2016}, abstract = {The effectiveness of different strategies against reservoir sedimentation is demonstrated herein using data sets of Asahi, Nunobiki and Dashidaira reservoirs in Japan. The applied strategies encompass sediment routing with a bypass tunnel, drawdown flushing during floods and sabo dam construction in the catchment. It is shown that bypassing and flushing are very efficient strategies enlarging reservoir life by 3 to 21 times up to many hundreds of years. Furthermore, it is revealed that also efforts in the catchment, e.g. sabo dam construction, is effective enlarging reservoir life by 2.4 times.}, language = {en} } @article{AuelAlbayrakSumietal.2017, author = {Auel, C. and Albayrak, I. and Sumi, T. and Boes, R.M.}, title = {Sediment transport in high-speed flows over a fixed bed. 2: Particle impacts and abrasion prediction}, series = {Earth Surface Processes and Landforms}, journal = {Earth Surface Processes and Landforms}, doi = {10.1002/esp.4132}, pages = {1365 -- 1383}, year = {2017}, abstract = {Single bed load particle impacts were experimentally investigated in supercritical open channel flow over a fixed planar bed of low relative roughness height simulating high-gradient non-alluvial mountain streams as well as hydraulic structures. Particle impact characteristics (impact velocity, impact angle, Stokes number, restitution and dynamic friction coefficients) were determined for a wide range of hydraulic parameters and particle properties. Particle impact velocity scaled with the particle velocity, and the vertical particle impact velocity increased with excess transport stage. Particle impact and rebound angles were low and decreased with transport stage. Analysis of the particle impacts with the bed revealed almost no viscous damping effects with high normal restitution coefficients exceeding unity. The normal and resultant Stokes numbers were high and above critical thresholds for viscous damping. These results are attributed to the coherent turbulent structures near the wall region, i.e. bursting motion with ejection and sweep events responsible for turbulence generation and particle transport. The tangential restitution coefficients were slightly below unity and the dynamic friction coefficients were lower than for alluvial bed data, revealing that only a small amount of horizontal energy was transferred to the bed. The abrasion prediction model formed by Sklar and Dietrich in 2004 was revised based on the new equations on vertical impact velocity and hop length covering various bed configurations. The abrasion coefficient kv was found to be vary around kv ~ 105 for hard materials (tensile strength ft > 1 MPa), one order of magnitude lower than the value assumed so far for Sklar and Dietrich's model.}, language = {en} } @article{AuelBoesZiegleretal.2011, author = {Auel, C. and Boes, R. and Ziegler, T. and Oertli, C.}, title = {Design and construction of the sediment bypass tunnel at Solis}, series = {Int. Journal on Hydropower and Dams}, journal = {Int. Journal on Hydropower and Dams}, pages = {62 -- 66}, year = {2011}, language = {en} } @inproceedings{AuelTheneMuellerHagemannetal.2017, author = {Auel, C. and Thene, J.R. and M{\"u}ller-Hagemann, M. and Albaryak, I. and Boes, R.M.}, title = {Abrasion prediction at Mud Mountain sediment bypass tunnel}, series = {Proc. 2nd Int. Workshop on Sediment Bypass Tunnels, FP12, Kyoto, Japan}, booktitle = {Proc. 2nd Int. Workshop on Sediment Bypass Tunnels, FP12, Kyoto, Japan}, publisher = {ETH Zurich}, doi = {10.25974/fhms-15142}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151422}, year = {2017}, abstract = {A major drawback of sediment bypass tunnels is the potential for severe invert abrasion due to intense bedload sediment transport. This paper briefly describes the abrasion phenomena as well as the available models used to predict invert material loss. The application and calibration is demonstrated on the basis of the Mud Mountain sediment bypass tunnel, Washington, USA.}, language = {en} } @inproceedings{MuellerHagemannAuelAlbaryaketal.2018, author = {M{\"u}ller-Hagemann, M. and Auel, C. and Albaryak, I. and Boes, R.M.}, title = {Bedload transport and hydro-abrasive erosion at steep bedrock rivers and hydraulic structures}, series = {Riverflow, Lyon, France}, booktitle = {Riverflow, Lyon, France}, year = {2018}, language = {en} } @inproceedings{AuelBerchtoldBoes2010, author = {Auel, C. and Berchtold, T. and Boes, R.M.}, title = {Sediment management in the Solis reservoir using a bypass tunnel}, series = {8th ICOLD European Club Symposium}, booktitle = {8th ICOLD European Club Symposium}, address = {Innsbruck, Austria}, doi = {10.25974/fhms-15164}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151647}, pages = {438 -- 443}, year = {2010}, abstract = {The Solis reservoir is located in the Alps in Grisons, Switzerland and is operated by the electric power company of Zurich (ewz). Since its construction in 1986, high sediment input during flood events has led to major aggradations in the reservoir. Up to date, nearly half of the original reservoir volume has been filled with sediments from upstream mountain torrents. The deltaic deposition starts extending into the active water volume. Therefore, ewz plans a sediment bypass tunnel to flush the incoming bedload around the dam to the downstream reach. In a first step the reservoir level during flood events is lowered to the minimum operation level. The delta is subjected to free surface flow and the bedload is transported over the delta and deposited further downstream. This sediment relocation decreases the delta volume within the active storage. During further flood events, the incoming sediment is led to the bypass tunnel intake using a guiding structure and flushed through the tunnel. If the flood exceeds the capacity of the bypass tunnel, the surplus flow passes the tunnel intake towards the bottom outlets with the bedload still being flushed through the tunnel. A skimming wall located upstream from the tunnel intake prevents driftwood blocking by leading it to the reservoir front where it can be safely removed. Both the sediment relocation due to water level drawdown and the flushing through the bypass tunnel are investigated and optimized in a hydraulic model at the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) of ETH Zurich. Additionally, the sediment relocation process in the model is compared with a relocation test in the prototype.}, language = {en} } @inproceedings{AuelAlbayrakBoes2015, author = {Auel, C. and Albayrak, I. and Boes, R.M.}, title = {Bed-load particle motion in supercritical open channel flows}, series = {Proc. 36th IAHR World Congress, Delft - The Hague, the Netherlands}, booktitle = {Proc. 36th IAHR World Congress, Delft - The Hague, the Netherlands}, publisher = {IAHR}, doi = {10.25974/fhms-15155}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151559}, year = {2015}, abstract = {Supercritical sediment-laden open channel flows occur in many hydraulic structures including dam outlets, weirs, and bypass tunnels. Due to high flow velocities and sediment flux severe problems such as erosion and abrasion damages are expected in these structures (Jacobs et al., 2001). Sediment bypass tunnels (SBT), as an effective measure to decrease reservoir sedimentation by bypassing sediments during floods, are exceptionally prone to high abrasion causing significant annual maintenance cost (Sumi et al., 2004; Auel and Boes, 2011). The Laboratory of Hydraulics, Hydrology and Glaciology (VAW) of ETH Zurich conducted a laboratory study to counteract these negative effects (Auel, 2014). The main goals of the project were to analyze the fundamental physical processes in supercritical flows as present in SBTs by investigating the mean and turbulence flow characteristics (Auel et al., 2014a), particle motion (Auel et al., 2014b; 2015b), and abrasion development caused by transported sediment. Besides new insights into the three listed topics, paramount interest is given to their inter-relations and the development of an easily applicable abrasion prediction model (Auel et al., 2015a). This paper presents selected results on the second topic, i.e. the analysis of saltation trajectories of single coarse particles in supercritical flow.}, language = {en} } @article{MuellerHagemannAlbayrakAueletal.2020, author = {M{\"u}ller-Hagemann, M. and Albayrak, I and Auel, C and Boes, RM}, title = {Field Investigation on Hydroabrasion in High-Speed Sediment-Laden Flows at Sediment Bypass Tunnels}, series = {Water 12 (2)}, journal = {Water 12 (2)}, publisher = {MDPI}, address = {Basel}, doi = {10.25974/fhms-15126}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151268}, year = {2020}, abstract = {Wear due to sediment particles in fluid flows, also termed hydroabrasion' or simply 'abrasion', is an omnipresent issue at hydraulic structures as well as in bedrock rivers. However, interactions between flow field, particle motion, channel topography, material properties and abrasion have rarely been investigated on a prototype scale, leaving many open questions as to their quantitative interrelations. Therefore, we investigated hydroabrasion in a multi-year field study at two Swiss Sediment Bypass Tunnels (SBTs). Abrasion depths of various invert materials, hydraulics and sediment transport conditions were determined and used to compute the abrasion coefficients kv of different abrasion models for high-strength concrete and granite. The results reveal that these models are useful to estimate spatially averaged abrasion rates. The kv-value is about one order of magnitude higher for granite than for high-strength concrete, hence, using material-specific abrasion coefficients enhances the prediction accuracy. Three-dimensional flow structures, i.e., secondary currents occurring both, in the straight and curved sections of the tunnels cause incision channels, while also longitudinally undulating abrasion patterns were observed. Furthermore, hydroabrasion concentrated along joints and protruding edges. The maximum abrasion depths were roughly twice the mean abrasion depths, irrespective of hydraulics, sediment transport conditions and invert material.}, language = {en} } @article{KoshibaAuelTsutsumietal.2018, author = {Koshiba, T. and Auel, C. and Tsutsumi, D. and Kantoush, S.A. and Sumi, T.}, title = {Application of an impact plate - bedload transport measuring system for high-speed flows}, series = {International Journal of Sediment Research}, journal = {International Journal of Sediment Research}, doi = {10.1016/j.ijsrc.2017.12.003}, pages = {35 -- 46}, year = {2018}, 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 2 mm 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.}, language = {en} } @article{AuelKobayashiTakemonetal.2017, author = {Auel, C. and Kobayashi, S. and Takemon, Y. and Sumi, T.}, title = {Effects of sediment bypass tunnels on grain size distribu-tion and benthic habitats in regulated rivers}, series = {International Journal of River Basin Management}, journal = {International Journal of River Basin Management}, doi = {10.1080/15715124.2017.1360320}, pages = {433 -- 444}, year = {2017}, abstract = {Four dams in Japan and Switzerland with Sediment Bypass Tunnels (SBT) as a measure against reservoir sedimentation were monitored to analyse the effects of sediment supply on the downstream environment based on up- to downstream differences in geomorphological and biological characteristics. SBT operation times ranged from 93 years at Pfaffensprung and 17 at Asahi to only three years at Solis and no operation at Koshibu. Sediment grain size distribution was monitored, and microhabitats and invertebrates were analysed in terms of richness and composition. Results showed that grain sizes were coarser down- than upstream at dams with newly established SBTs, while they were similar or finer for dams with long SBT operation. Analysis of biotic data revealed that microhabitat and invertebrate richness was low directly below the dam but increased further downstream the longer the SBT operation. Sedentary species dominated at locations where bed conditions were stable, e.g. directly downstream of the dam at Koshibu. Recovery of downstream environment with increasing SBT operation time was disclosed by the Bray-Curtis similarity index, which evaluated an overlap between up- and downstream reaches for both microhabitat composition and invertebrate communities. With increasing operation time, both indices increased, revealing the positive effects of long-term SBT operation.}, language = {en} } @article{AuelAlbayrakSumietal.2017, author = {Auel, C. and Albayrak, I. and Sumi, T. and Boes, R.M.}, title = {Sediment transport in high-speed flows over a fixed bed. 1: Particle dynamics}, series = {Earth Surface Processes and Landforms}, journal = {Earth Surface Processes and Landforms}, doi = {10.1002/esp.4128}, pages = {1384 -- 1396}, year = {2017}, abstract = {Particle dynamics are investigated experimentally in supercritical high-speed open channel flow over a fixed planar bed of low relative roughness height simulating flows in high-gradient non-alluvial mountain streams and hydraulic structures. Non-dimensional equations were developed for transport mode, particle velocity, hop length and hop height accounting for a wide range of literature data encompassing sub- and supercritical flow conditions as well as planar and alluvial bed configurations. Particles were dominantly transported in saltation and particle trajectories on planar beds were rather flat and long compared with alluvial bed data due to (1) increased lift forces by spinning motion, (2) strongly downward directed secondary currents, and (3) a planar flume bed where variation in particle reflection and damping effects were minor. The analysis of particle saltation trajectories revealed that the rising and falling limbs were almost symmetrical contradicting alluvial bed data. Furthermore, no or negligible effect of particle size and shape on particle dynamics were found. Implications of experimental findings for mechanistic saltation-abrasion models are briefly discussed.}, language = {en} } @article{AuelBoesSumi2018, author = {Auel, C. and Boes, R.M. and Sumi, T.}, title = {Abrasion prediction at Asahi sediment bypass tunnel based on Ishibashi's formula}, series = {Journal of Applied Water Engineering and Research}, journal = {Journal of Applied Water Engineering and Research}, doi = {10.1080/23249676.2016.1265470}, pages = {125 -- 138}, year = {2018}, abstract = {Abrasion in a concrete-lined sediment bypass tunnel is estimated using a Japanese state-of-the-art prediction model and validated by measured invert abrasion data at Asahi Reservoir, Japan. The model is described in detail, certain shortcomings are disclosed, and a revised version is proposed. The model consists of a kinetic energy term accounting for the impact by saltating particles, and a friction work term accounting for the grinding stress. It is found that the latter term yields concrete abrasion values being consistently a multiple compared to its kinetic term contradicting other research. Based on that, and a possible particle impact angle inconsistency, it is proposed to omit the friction work term. It is shown that the calculated abrasion is overestimated by 138\% on average compared with that measured, if both terms are accounted for. However, promising results are obtained with only 30\% overestimation by neglecting the friction work term.}, language = {en} } @article{AuelAlbayrakBoes2014, author = {Auel, C. and Albayrak, I. and Boes, R.M.}, title = {Turbulence characteristics in supercritical open channel flows: Effects of Froude number and aspect ratio}, series = {Journal of Hydraulic Engineering ASCE}, journal = {Journal of Hydraulic Engineering ASCE}, doi = {10.1061/(ASCE)HY.1943-7900.0000841}, year = {2014}, abstract = {An experimental investigation of supercritical uniform and gradually varied open channel flows is presented for a wide range of Froude numbers and flume width-to-flow depth aspect ratios. The instantaneous streamwise and vertical flow velocities were measured in a laboratory flume over the entire width using a two dimensional-laser Doppler anemometry (2D-LDA) system to determine turbulence intensities, and bed and Reynolds shear stresses. The mean velocity patterns show undulation across the flume, indicating the presence of counterrotating secondary current cells. These currents redistribute turbulence intensities and bed and Reynolds shear stresses across the flume. For aspect ratios ≤ 4-5, i.e., narrow open channel flow, the velocity-dip phenomenon is identified both in the streamwise velocity and the Reynolds shear stress distributions. For high aspect ratios, i.e., wide open channel flow, the strength of secondary currents diminish toward the flume center, resulting in a 2D flow farther away from the walls and no velocity-dip phenomenon. Froude number effects on the flow characteristics are less pronounced compared to the aspect ratio effects. At high Froude numbers, the results for narrow and wide open channel flows agree well with literature data. The log-law holds in the inner region across the entire flume width for all investigated Froude numbers and aspect ratios. The Reynolds shear stress distribution agrees well with the computed spanwise bed shear stress distribution. At the flume side walls, the bed shear stresses are 20-50 \% higher than the mean values. These results are verified with an engineering example in which high sediment transport and corresponding deep abrasion patterns at the side walls were observed.}, language = {en} } @article{AuelBerchtholdBoes2010, author = {Auel, C. and Berchthold, T. and Boes, R.}, title = {Entlandung des Stausees Solis mittels Geschiebeumleitstollen}, series = {Wasserwirtschaft}, journal = {Wasserwirtschaft}, pages = {117 -- 119}, year = {2010}, language = {de} } @article{AuelBoes2017, author = {Auel, C. and Boes, R.}, title = {Sedimentumleitstollen - eine nachhaltige Maßnahme gegen Stauraumverlandung}, series = {Wasserwirtschaft}, journal = {Wasserwirtschaft}, number = {4}, pages = {42 -- 47}, year = {2017}, language = {de} } @inproceedings{Auel2018, author = {Auel, C.}, title = {Sediment bypassing, a sustainable and co-friendly strategy against reservoir sedimentation}, series = {VINGT SIXI{\`E}ME CONGR{\`E}S DES GRANDS BARRAGES Vienne, Juillet 2018}, booktitle = {VINGT SIXI{\`E}ME CONGR{\`E}S DES GRANDS BARRAGES Vienne, Juillet 2018}, publisher = {COMMISSION INTERNATIONALE DES GRANDES BARRAGES}, doi = {10.25974/fhms-15140}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151407}, year = {2018}, abstract = {Without adequate measures, reservoirs are not sustainable, neither the reservoir itself due to continuous sedimentation, nor the downstream ecosystem due to altered sediment continuity. Appropriate actions are inevitable and require a systematic sedimentation management. Sediment bypassing constitutes one effective strategy that routes sediment load around reservoirs during floods. A sediment bypass system has the advantage that only newly entrained sediment is diverted from the upstream to the downstream reach thereby re-establishing sediment connectivity. Hence, such a system contributes to a sustainable water resources management while taking the downstream environment into consideration. This paper gives a state-of-the-art overview encompassing design, bypass efficiency, hydraulics, challenges due to abrasion, positive effects on both downstream morphology and ecology, and makes design recommendations.}, language = {en} } @inproceedings{AuelTheneCarrolletal.2018, author = {Auel, C. and Thene, J.R. and Carroll, J. and Holmes, C. and Boes, R.M.}, title = {Rehabilitation of the Mud Mountain bypass tunnel invert}, series = {VINGT SIXI{\`E}ME CONGR{\`E}S DES GRANDS BARRAGES Vienne, Juillet 2018}, booktitle = {VINGT SIXI{\`E}ME CONGR{\`E}S DES GRANDS BARRAGES Vienne, Juillet 2018}, publisher = {COMMISSION INTERNATIONALE DES GRANDES BARRAGES}, doi = {10.25974/fhms-15141}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151413}, year = {2018}, abstract = {This paper describes the design of the new tunnel invert lining of the 9-foot tunnel at Mud Mountain Dam, Washington, USA. The tunnel diverts all bed load sediments into the tailwater. Major invert abrasion has been observed in the existing steel lining. The new invert design consists of 0.59 m2 and 0.79 m2 granite blocks that are 0.25 m thick and placed tightly together along the tunnel. Stability analysis showed factors of safety ranging from 1.2 to 2.6 against uplift. This will be achieved with strip drains placed in the bedding material along the tunnel. A service-design-life analysis was performed using abrasion prediction modelling. This model was based on abrasion measurement data acquired from granite field tests at Pfaffensprung sediment bypass tunnel, Switzerland. The estimated annual abrasion depths for the granite were approximately 0.50 mm/year for average sediment transport conditions.}, language = {en} } @inproceedings{AuelGruberKircheretal.2021, author = {Auel, C. and Gruber, E. and Kircher, F. and Fritzer, R. and Moritz, C. and Huber, T.}, title = {Rehabilitation of Gaulwerk hydropower plant considering environment, sediment management and flood protection}, series = {ICOLD Symposium on Sustainable Development of Dams and River Basins, 24th - 27th February, 2021, New Delhi}, booktitle = {ICOLD Symposium on Sustainable Development of Dams and River Basins, 24th - 27th February, 2021, New Delhi}, publisher = {ICOLD}, doi = {10.25974/fhms-15137}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151377}, year = {2021}, abstract = {The Gaulwerk hydropower plant (HPP) has a design discharge of 3.5 m3/s and generates about 6.5 GWh per year. The HPP has been in operation since 1963 and uses the flow of two alpine streams. The HPP impounds a 300 m long reservoir with a 6.50 m high weir. The storage is completely filled with sediments and is classified as a valuable habitat for fauna and flora. Due to the sedimentation, the area upstream of the reservoir head inundates about two to three times per year during small flood events, leading to complaints from affected landowners and adjacent municipalities. To investigate sustainable solutions, a study of alternatives has been carried out in which three alternatives to im-prove both the sediment and flood situation are being investigated. In addition, the residual flow release will be adjusted and fish facilities realized in all alternatives. The paper will summarize the analysis of the alternatives encompassing the (1) flood situation, (2) sediment management, (3) reha-bilitation measures of the hydraulic structures and their costs and (4) the environmental impact.}, language = {en} } @inproceedings{KobayashiAuelSumietal.2016, author = {Kobayashi, S. and Auel, C. and Sumi, T. and Takemon, Y.}, title = {Recovery of riverbed features and invertebrate community in degraded channels by sediment supply through bypass tunnel}, series = {Proc. 12th Int. Conference on Hydroscience and Engineering, Tainan, Taiwan}, booktitle = {Proc. 12th Int. Conference on Hydroscience and Engineering, Tainan, Taiwan}, publisher = {ICHE}, doi = {10.25974/fhms-15144}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151447}, year = {2016}, abstract = {Sediment, which deposits and damages the function of reservoirs, is an essential element of aquatic habitats in downstream ecosystems. We reviewed ecosystem features of degraded channels associated with sediment deficiency below dams and ecosystem responses to changes in sediment conditions after management practices in Japan. Sediment bypass tunnel (SBT) is an effective way to transport sufficient amount of sediment to downstream ecosystems. Based on a concept of suitable mass and size of sediment for ecosystem, some effects and limitations of SBT on downstream ecosystems were discussed.}, language = {en} } @inproceedings{AuelSumi2016, author = {Auel, C. and Sumi, T.}, title = {Abrasion damage in sediment bypass tunnels}, series = {River Sedimentation: Proc. 12th Int. Conference on Hydroscience and Engineering, Tainan, Taiwan, 02-0020}, booktitle = {River Sedimentation: Proc. 12th Int. Conference on Hydroscience and Engineering, Tainan, Taiwan, 02-0020}, publisher = {ICHE}, doi = {10.25974/fhms-15143}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151436}, year = {2016}, abstract = {Sediment bypass tunnels are an effective and sustainable strategy against reservoir sedimentation. Sediments are diverted into the down-stream during floods without deposition in the reservoir, hence mor-phological and ecological variability increases. One major drawback of these tunnels is the severe invert abrasion due to a combination of high flow velocities and bedload sediment transport. The abrasion phenom-ena is briefly described, different abrasion prediction models are pre-sented and their applicability for the estimation of concrete abrasion is discussed.}, language = {en} } @inproceedings{AuelKobayashiSumietal.2016, author = {Auel, C. and Kobayashi, S. and Sumi, T. and Takemon, Y.}, title = {Effects of sediment bypass tunnels on sediment grain size distribution and benthic habitats}, series = {River Sedimentation: Proc. 13th Int. Symposium on River Sedimentation}, booktitle = {River Sedimentation: Proc. 13th Int. Symposium on River Sedimentation}, publisher = {CRC Press}, address = {Stuttgart, Germany}, pages = {825 -- 832}, year = {2016}, language = {en} } @inproceedings{AuelHagemannAlbayraketal.2015, author = {Auel, C. and Hagemann, M. and Albayrak, I. and Boes, R.M.}, title = {Optimizing the sustainability of sediment bypass tunnels to counter reservoir sedimentation}, series = {Proc. 25th ICOLD Congress, Q99 R31, Stavanger, Norway}, booktitle = {Proc. 25th ICOLD Congress, Q99 R31, Stavanger, Norway}, publisher = {ICOLD}, doi = {10.25974/fhms-15151}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151518}, pages = {431 -- 452}, year = {2015}, abstract = {In order to prevent reservoir sedimentation, sediment bypass tunnels can be an efficient countermeasure restoring sediment continuity of impounded rivers. Although supercritical open channel flow conditions in these tunnelsprevent tun-nel blockage, in combination with the high bypassed sediment volume it may lead tosevere abrasion damages on inverts. Consequently,wear termed hydroabra-sionoccurs. Based on laboratoryexperiments, a theoretical model was devel-oped to predict abrasion rates and service life timeof sediment bypass tunnels. Insituexperiments are further conducted for model calibration to provide an abrasion prediction approach for field applications.Finally,recommendations concerning the hydraulic design of the tunnel as well as the structural design ofthe invertareprovided.}, language = {en} } @inproceedings{AuelAlbayrakSumietal.2015, author = {Auel, C. and Albayrak, I. and Sumi, T. and Boes, R.M.}, title = {Saltation-abrasion model for hydraulic structures}, series = {Proc. 1st Int. Workshop on Sediment Bypass Tunnels, VAW Mitteilungen 232}, booktitle = {Proc. 1st Int. Workshop on Sediment Bypass Tunnels, VAW Mitteilungen 232}, publisher = {ETH Zurich}, doi = {10.25974/fhms-15152}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151528}, pages = {101 -- 121}, year = {2015}, abstract = {The derivation of an abrasion prediction model for concrete hydraulic structures valid in supercritical flows is presented herein. The state of the art saltation-abrasion model from Sklar and Dietrich (2004) is modified using the findings of a recent research pro-ject on the design and layout of sediment bypass tunnels. The model correlates the im-pacting parameters with the invert material properties by an abrasion coefficient kv. The value of this coefficient is verified by a similarity analysis to bedrock abrasion in river systems applying a correlation between the abrasion rate and the bed material strength. A sensitivity analysis reveals that the saltation-abrasion model is highly dependent on an adequate estimation of kv. However, as a first order estimate the proposed model en-ables the practical engineer to estimate abrasion at hydraulic structures prone to super-critical flows.}, language = {en} } @inproceedings{AuelBoesSumi2015, author = {Auel, C. and Boes, R.M. and Sumi, T.}, title = {Abrasion damage estimation of sediment bypass tunnels: Validation and comparison of two prediction models}, series = {Annuals of Disaster Prevention Research Institute 58B, Kyoto University, Japan}, booktitle = {Annuals of Disaster Prevention Research Institute 58B, Kyoto University, Japan}, publisher = {Kyoto University}, doi = {10.25974/fhms-15154}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151547}, pages = {540 -- 549}, year = {2015}, abstract = {Abrasion damage estimation of sediment bypass tunnels: Validation and comparison of two prediction models. Annuals of Disaster Prevention Research Institute 58B, Kyoto Univer-sity, Japan}, language = {en} } @inproceedings{KoshibaAuelTsutsumietal.2016, author = {Koshiba, T. and Auel, C. and Tsutsumi, D. and Kantoush, S.A. and Sumi, T.}, title = {Improvement of a bedload transport rate measuring systems in sediment bypass tunnels}, series = {River Sedimentation: Proc. 13th Int. Symposium on River Sedimentation}, booktitle = {River Sedimentation: Proc. 13th Int. Symposium on River Sedimentation}, publisher = {CRC Press}, address = {Stuttgart, Germany}, isbn = {978-1-138-02945-3}, doi = {10.25974/fhms-15146}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151462}, pages = {1038 -- 1045}, year = {2016}, abstract = {For long term use of dams, it is required to develop methods of sediment management in reservoirs. As one method, Sediment BypassTunnels (SBT) are operated in Japan and Switzerland to prevent reservoir sedimentation. SBT reduces sedimentation in reservoirs by routing the incoming sediments around the dam. SBT, however, is prone to severe invert abrasion caused by high sediment flux. Therefore, it is necessary to establish a measurement system of sediment transport rates in the SBT. A geophone was experimentally investigated in a laboratory flume at ETH Zurich. The sediment transport rate is calculated based on the plate vibration caused by hitting of gravels. In this paper, in order to alleviate disadvantages of a geophone, two newly developed sensor systems, a plate microphone and plate vibration sensor, are suggested and the results of their calibration experiments are shown. Finally, they are compared with the existing methods.}, language = {en} } @inproceedings{KoshibaSumiTsutsumietal.2016, author = {Koshiba, T. and Sumi, T. and Tsutsumi, D. and Kantoush, S.A. and Auel, C.}, title = {Development of a bedload transport meas-uring system in sediment bypass tunnels}, series = {84th Annual Meeting of ICOLD, Johannesburg, South Africa 4-49-4-58}, booktitle = {84th Annual Meeting of ICOLD, Johannesburg, South Africa 4-49-4-58}, publisher = {ICOLD}, isbn = {978-0-620-71042-8}, doi = {10.25974/fhms-15150}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151506}, year = {2016}, abstract = {Sediment Bypass Tunnels are operated to divert sediment around reservoirs reducing reservoir sedimentation. A major drawback of these tunnels is severe invert abrasion due to high velocity and sediment flows. There is an urgent need to establish innovative measurement systems of sediment transport rates in SBTs. In this paper, three bedload measuring systems, namely hydrophones, geophones, and newly developed plate microphones are introduced and compared. The Koshibu SBT is planned to operate from 2016. Plate microphones combined with geophones and other planned systems are installed in the tunnel. Results of preliminary tests and installation plans of bedload measurement are presented.}, language = {en} } @inproceedings{KobayashiAuelSumietal.2016, author = {Kobayashi, S. and Auel, C. and Sumi, T. and Takemon, Y.}, title = {Effects of sediment supply by bypass tunnels on bed to-pography, grain size, and invertebrate habitat}, series = {Proc. 20th IAHR APD Congress, Colombo, Sri Lanka, 5B008}, booktitle = {Proc. 20th IAHR APD Congress, Colombo, Sri Lanka, 5B008}, publisher = {IAHR}, doi = {10.25974/fhms-15147}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151473}, year = {2016}, abstract = {To understand the effects of sediment bypass on environmental recovery of the degraded channels below dams, bed topography and bed materials above and below dam reaches were surveyed by ground-based measurements and aerial photos using quadrocopter. Coarse bed materials such as boulders were more represented below than above the Koshibu dam, where the bypass tunnel had not been in operation yet. The coarse materials formed steps and protruded in the water column within riffles and runs, both of which can increase slow-flow areas, below the dam. On the other hand, sand, gravel, and cobbles were abundant below as much as above the Asahi dam, where the bypass tunnel had been operated for >17 years. The downstream environment in terms of bed topography and grain size seems to have almost been recovered for the Asahi dam. However, less representation of large cobbles and boulders below the dam suggested a possibility of a selective deposition of coarse materials at the upstream of the bypass tunnel inlet.}, language = {en} } @inproceedings{OertliAuel2015, author = {Oertli, C. and Auel, C.}, title = {Solis sediment bypass tunnel: First operation experiences}, series = {Proc. 1st Int. Workshop on Sediment Bypass Tunnels, VAW Mitteilungen}, booktitle = {Proc. 1st Int. Workshop on Sediment Bypass Tunnels, VAW Mitteilungen}, publisher = {ETH Zurich}, doi = {10.25974/fhms-15153}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151539}, pages = {223 -- 233}, year = {2015}, abstract = {The Solis dam was built in 1986 by the Electric Power Company of Zurich (ewz). Ever since the construction, large amounts of sediments accumulated in the reservoir and led to severe sediment aggradation. As a consequence, the storage volume was reduced by about 50\% till 2012 causing loss of energy production. Additionally, in the near future sediments may have caused severe damage at the dam due to blockage of the bottom outlets. Therefore, in 2011 and 2012 a sediment bypass tunnel was realized in order to redirect the incoming sediments into the tailwater to inhibit sediment aggradation. Since its inauguration, the tunnel was operated four times including a 100-year flood event in August 2014. First operational experiences are described herein.}, language = {en} } @inproceedings{Auel2009, author = {Auel, C.}, title = {Entlandung des Stausees Solis mit Hilfe eines Geschiebeumleitstollens - hydraulische Modellversuche}, series = {Proc. 11. JuWi-Treffen, Communication No. 40, Laboratoire de Constructions Hydrauliques (LCH)}, booktitle = {Proc. 11. JuWi-Treffen, Communication No. 40, Laboratoire de Constructions Hydrauliques (LCH)}, address = {Switzerland}, doi = {10.25974/fhms-15168}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151685}, pages = {159 -- 166}, year = {2009}, abstract = {Das Reservoir der Talsperre Solis in Graub{\"u}nden wurde 1986 vom Elektrizit{\"a}tswerk der Stadt Z{\"u}rich (ewz) in Betrieb genommen. Bei Hochwasserereignissen werden grosse Sedimentmengen in den Stausee transportiert. {\"U}ber 25 \% des urspr{\"u}nglichen Reservoirvolumens sind bereits verlandet. Aus diesem Grund plant ewz den Bau eines Geschiebeumleitstollens, der das bei Hochwasser ankommende Sediment um die Talsperre herum in Richtung Unterwasser leitet. Die Versuchsanstalt f{\"u}r Wasserbau, Hydrologie und Glaziologie (VAW) der ETH Z{\"u}rich untersucht und optimiert in einem hydraulischen Modell den projektierten Umleitstollen. Bei Hochwasser wird der Stausee auf den minimalen Betriebswasserspiegel abgesenkt, der Verlandungsk{\"o}rper liegt gr{\"o}sstenteils frei, das Sediment erodiert. Mit Hilfe einer Leitkonstruktion wird die Str{\"o}mung in Richtung Einlaufbauwerk des Stollens gelenkt und der Abfluss sowie das Geschiebe durch diesen geleitet. Bei Abfl{\"u}ssen, die die Ausbaukapazit{\"a}t des Stollens (HQ5) {\"u}berschreiten, wird die {\"u}bersch{\"u}ssige Str{\"o}mung in den vorderen Bereich des Sees in Richtung Grundablass abgef{\"u}hrt. Das Geschiebe wird dennoch nahezu vollst{\"a}ndig in den Stollen eingeleitet. Bei Hochwasser mit Schwemmholzaufkommen wird mit Hilfe einer Tauchwand sowie einer Teilablleitung des Hochwasserabflusses in den vorderen Seebereich verhindert, dass Schwemmholz in den Umleitstollen eingezogen wird.}, language = {de} } @book{Auel2014, author = {Auel, C.}, title = {Flow characteristics, particle motion and invert abrasion in sediment bypass tunnels}, series = {PhD thesis 22008, also published as VAW Mitteilungen 229 (R. Boes ed.)}, journal = {PhD thesis 22008, also published as VAW Mitteilungen 229 (R. Boes ed.)}, publisher = {ETH Zurich, Switzerland}, doi = {10.3929/ethz-a-010243883}, publisher = {FH M{\"u}nster - University of Applied Sciences}, year = {2014}, abstract = {Sediment bypass tunnels are an effective countermeasure against reservoir sedimenta-tion. They are operated at supercritical sediment-laden open channel flow conditions. The major drawback of these tunnels, besides high construction costs, is the severe invert abrasion caused by these flows provoking high annual maintenance costs. The project goal was to analyze the fundamental physical processes and to develop design criteria to decrease these negative effects. A laboratory study was performed in a scaled hydraulic model flume. The project was divided in three main test phases giving new insights into the dynamics of turbulence structures and particle motions, resulting bed abrasion and their interactions in a supercritical open channel flow, respectively. In phase A the mean and turbulent flow characteristics were investigated. In phase B single sediment particle motion was analyzed. In phase C the invert abrasion development in time and space was examined. Phase A revealed that secondary current cells affect the turbulent flow pattern leading to high bed shear stress at the wall vicinity. In phase B it was found, that particles were dominantly transported in saltation. Relationships between the saltation probability, and particle hop lengths and heights to the flow Shields parameter were found. The specific impact energy was determined by the impact velocity, number of impacts and the amount of particles transported in time. In phase C the results show that bed abrasion progresses with time both in the lateral and vertical direction. Two lateral incision chan-nels developed along the flume side walls at narrow flow conditions occurring at low flume-width to flow-depth aspect ratios b/h < 4-5, whereas randomly distributed pot-holes were found at wide channels where b/h > 4-5. The observed abrasion patterns match well with the spanwise bed shear stress distributions found in phase A. Further-more it was found that the abraded mass linearly increases with the transported sedi-ment mass allowing for a linear fit. Further results showed that abrasion increased with flow intensity and sediment transport rate, with highest values for the mean particle diameter category, whereas abrasion decreased with increasing material strength. Finally, a new formulation was developed based on Sklar's saltation abrasion model. A new abrasion coefficient CA is introduced correlating the impact energy and material properties with the gravimetric abrasion rate.}, language = {en} } @article{AuelAlbayrakBoes2012, author = {Auel, C. and Albayrak, I. and Boes, R.M.}, title = {Hydraulische Modellierung der Hydroabrasion}, series = {VAW Mitteilungen}, journal = {VAW Mitteilungen}, publisher = {ETH Zurich}, doi = {10.25974/fhms-15171}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151717}, year = {2012}, abstract = {Hydroabrasion tritt im alpinen Raum haupts{\"a}chlich bei Wasserbauwerken auf, die durch hohe Fließgeschwindigkeiten und große Sedimentfrachten belastet werden. Dies sind beispielswei-se Wehrschwellen in Fl{\"u}ssen, Wasserfassungen von Wasserkraftwerken und vor allem Sedi-mentumleitstollen. Letztere dienen dazu sedimentreiche Hochwasserspitzen um die Talsperre herum in den Unterlauf des Flusses zu leiten. Sie verhindern so eine fortschreitende Verlan-dung des Stauraums. Es gibt verschiedene Konzepte, dem Problem der Hydroabrasion entgegen zu wirken. Einer-seits kann der Umleitstollen hydraulisch optimiert werden, um die Einwirkung auf die Sohle zu minimieren. Auf der anderen Seite kann deren Widerstand verbessert werden. An der Ver-suchsanstalt f{\"u}r Wasserbau, Hydrologie und Glaziologie (VAW) der ETH Z{\"u}rich werden zur Zeit zwei Forschungsarbeiten durchgef{\"u}hrt, die sich jeweils diesen Aspekten widmen. Dieser Beitrag befasst sich mit der hydraulischen Optimierung von Sedimentumleitstollen mit Hilfe von großskaligen Laborversuchen. In insgesamt drei Versuchsreihen werden die Mittelwert- und Turbulenz-Fließcharakteristik von schießendem Abfluss in einer Versuchsrinne mittels eines Laser-Doppler Anemometrie-Systems (LDA) aufgenommen, die Fortbewegungsart des Sediments mittels eines High-Speed Kamera-Systems analysiert sowie die Abrasion der Stollensohle untersucht. In Abh{\"a}ngigkeit des Sohlgef{\"a}lles, des Durchflusses, der Gr{\"o}ße und Menge der Sedimentfracht erfolgt die Fortbewegung des Sedimentkorns h{\"u}pfend, rollend oder gleitend und verursacht unterschied-liche Abrasionserscheinungen in der Stollensohle. Die Ergebnisse der LDA Experimente zei-gen, dass, abh{\"a}ngig vom Verh{\"a}ltnis Gerinnebreite zur Abflusstiefe, Sekund{\"a}rstr{\"o}mungen auf-treten. Diese Sekund{\"a}rstr{\"o}mungen beeinflussen im untersuchten Froude-Zahlenbereich 2, 4 und 8 das longitudinale Str{\"o}mungsprofil sowie die Verteilung der Sohlen- bzw. Reynolds-Schubspannungen und der Turbulenzintensit{\"a}t und somit letztlich die Fortbewegungsart des Sedimentkorns in der Wassers{\"a}ule. Mittels der drei Versuchsreihen sollen bestm{\"o}gliche hydraulische Bedingungen f{\"u}r Sedimen-tumleitstollen gefunden werden, um die Hydroabrasion und somit die Unterhaltskosten signi-fikant zu minimieren.}, language = {de} } @inproceedings{BoesAuelHagemannetal.2014, author = {Boes, R.M. and Auel, C. and Hagemann, M. and Albayrak, I.}, title = {Sediment bypass tunnels to mitigate reservoir sedimentation and restore sediment continuity}, series = {Reservoir Sedimentation}, booktitle = {Reservoir Sedimentation}, publisher = {Taylor and Francis Group}, address = {London, UK}, isbn = {978-1-138-02675-9}, doi = {10.25974/fhms-15156}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151569}, pages = {221 -- 228}, year = {2014}, abstract = {Worldwide, a large number of reservoirs impounded by dams are rapidly filling up with sediments. As on a global level the loss of reservoir volume due to sedimentation increases faster than the creation of new storage volume, the sustainability of reservoirs may be questioned if no countermeasures are taken. This paper gives an overview of the amount and the processes of reservoir sedimentation and its impact on dams and reservoirs. Furthermore, sediment bypass tunnels as a countermeasure for small to medium sized reservoirs are discussed with their pros and cons. The issue of hydroabrasion is highlighted, and the main design features to be applied for sediment bypass tunnels are given.}, language = {en} } @inproceedings{AuelBoes2012, author = {Auel, C. and Boes, R.M.}, title = {Sustainable reservoir management using sediment bypass tunnels}, series = {Proc. 24th ICOLD Congress, Q92 R16, Kyoto, Japan}, booktitle = {Proc. 24th ICOLD Congress, Q92 R16, Kyoto, Japan}, publisher = {ICOLD}, doi = {10.25974/fhms-15160}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151605}, pages = {224 -- 241}, year = {2012}, abstract = {Reservoir sedimentation is an increasing problem affecting the majority of reservoirs both in Switzerland and worldwide. As many dams are more than 50 years of age, this problem is becoming more and more serious nowadays. Res-ervoir sedimentation leads to various severe problems such as a decisive de-crease of the active reservoir volume leading to both loss of energy production and water available for water supply and irrigation. These problems will intensify in the near future, because sediment supply tends to increase due to climate change. Therefore, countermeasures have to be developed. They can be divided into the three main categories sediment yield reduction, sediment routing and sediment removal. This paper focuses on the sediment routing using sediment bypass tunnels. Sediment bypass tunnels are an effective means to decrease the reservoir sedimentation process. By routing the sediments around the reservoir into the tailwater, sediment accumulation is reduced significantly. However, the number of sediment bypass tunnels in the world is limited primarily due to high investment and maintenance costs. The main problem of all bypass tunnels is the invert abrasion due to high velocities in combination with high sediment transport. Three Swiss bypass tunnel examples suffering invert abrasion are presented in this paper. Furthermore, VAW started a research project to investigate the invert abrasion process by conducting hydraulic scale tests in the laboratory. The goal of this research project is to establish general design criteria for optimal flow con-ditions where both sediment depositions in the tunnel are avoided and the result-ing abrasion damages are kept at a minimum.}, language = {en} } @inproceedings{AuelAlbayrakBoes2014, author = {Auel, C. and Albayrak, I. and Boes, R.M.}, title = {Bedload particle velocity in supercritical open channel flows}, series = {Proc. 7th River Flow, Int. Conference on Fluvial Hydraulics (Schleiss et al. eds.)}, booktitle = {Proc. 7th River Flow, Int. Conference on Fluvial Hydraulics (Schleiss et al. eds.)}, publisher = {Taylor and Francis}, isbn = {978-1-138-02674-2}, doi = {10.25974/fhms-15157}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151579}, pages = {923 -- 931}, year = {2014}, abstract = {Single glass sphere motion recordings were conducted in a transitional-rough bed open channel at steady and highly supercritical flow similar to hydraulic conditions in sediment bypass tunnels. A high speed camera with a maximum resolution of 2,560 × 2,160 pixels was used to record the movement of bedload particles with diameters of D = 5.3, 10.3 and 17.5 mm. An in-house developed Particle Tracking Velocimetry (PTV) program was used to determine the transport mode and velocities of each particle for a wide range of Froude numbers up to Fo = 6. The relative roughness defined as the ratio of the bed roughness height ks to the water depth h varied from ks/h = 0.02-0.03. Particles were observed to move in rolling and saltation modes depending on the Shields number. The particle velocity shows a linearly increasing relationship with both friction velocity and Froude number nearly independent on the particle diameter. A linear relationship was also found between rolling and saltating particle velocities indicating that particle velocity does not depend on the transport mode in the range of the investigated hydraulic conditions. Scaling of particle velocity with the wave celerity plotted as a function of the Froude number adequately merged external data sets with the present data. As a consequence, a linear fit for a large Froude number range was obtained.}, language = {en} } @inproceedings{AuelBoes2011, author = {Auel, C. and Boes, R.M.}, title = {Sediment bypass tunnel design - review and outlook}, series = {Proc. ICOLD Symposium - Dams under changing challenges (Schleiss \& Boes, eds.), 79th Annual Meeting of ICOLD, Lucerne, Switzerland}, booktitle = {Proc. ICOLD Symposium - Dams under changing challenges (Schleiss \& Boes, eds.), 79th Annual Meeting of ICOLD, Lucerne, Switzerland}, publisher = {Taylor and Francis}, address = {London, UK}, isbn = {978-0-415-68267-1}, doi = {10.25974/fhms-15163}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151631}, pages = {403 -- 412}, year = {2011}, abstract = {Reservoir sedimentation is increasingly affecting the majority of reservoirs all over the world. As many dams are more than 50 years of age, this problem is becoming more and more seriou403s nowadays. Reservoir sedimentation leads to various severe problems such as a decisive decrease of the active reservoir volume leading to both loss of energy production and water available for water supply and irrigation. These problems will intensify in the very next future, because sediment supply tends to increase due to climate change. Therefore coun-termeasures have to be developed. They can be divided into the three main categories sediment yield reduction, sediment routing and sediment removal. This paper focuses on sediment routing by means of sediment bypass tunnels. Sediment bypass tunnels are an effective measure to stop or at least decrease the reservoir sedimentation process. By routing the sediments around the reservoir into the tailwater in case of flood events sediment accumulation of both bed load and suspended load is reduced significantly. However, the number of sediment bypass tunnels in the world is limited primarily due to high investment and above all maintenance costs. The state-of-the-art design criteria of constructing bypass tunnels are summarized herein; major problems such as tunnel invert abrasion are discussed. The need for further research regarding sediment transport in bypass tunnels and invert abrasion is highlighted.}, language = {en} } @inproceedings{AlbayrakAuelBoes2013, author = {Albayrak, I. and Auel, C. and Boes, R.M.}, title = {Supercritical flow in sediment bypass tunnels}, series = {Proc. 12th Int. Symp. on River Sedimentation. Advances in River Sediment Research}, booktitle = {Proc. 12th Int. Symp. on River Sedimentation. Advances in River Sediment Research}, publisher = {Taylor and Francis}, address = {London, UK}, isbn = {978-1-138-00062-9}, doi = {10.25974/fhms-15159}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151597}, pages = {1867 -- 1875}, year = {2013}, abstract = {This paper deals with an experimental investigation of the mean and turbulence characteristics of supercritical quasi-uniform and gradually varied open-channel flows over a transitional rough bed. These conditions are typical for sediment bypass tunnels. The results show that the log-law holds well in the inner region across the channel. The roughness shifts the velocity profiles downward by an amount of ΔU+. The velocity-dip phenomenon and strong secondary currents exist in the channel for narrow open-channel flow. These currents cause the Reynolds shear stress distributions to deviate from the linear distribution and an undulation on the transversal distribution of the bed shear stress, which matches with the bed abrasion pattern. The streamwise turbulence intensity profiles deviate from the semi-empirical universal function whereas the vertical turbulence intensity profiles fit well with it only at the centerline of the channel. A strong wall effect exists on the turbulence intensities in the outer region.}, language = {en} } @inproceedings{AuelBoes2011, author = {Auel, C. and Boes, R.M.}, title = {Sediment bypass tunnel design - hydraulic model tests}, series = {Proc. Hydro 2011 - Practical solutions for a sustainable future}, booktitle = {Proc. Hydro 2011 - Practical solutions for a sustainable future}, publisher = {Aqua-Media International Ltd}, address = {Prague, Czech Republic}, doi = {10.25974/fhms-15162}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151625}, year = {2011}, abstract = {Reservoir sedimentation, a serious problem affecting the majority of reservoirs worldwide, was not systematically accounted for in the past. After 50 years of operation, a constantly decreasing reservoir volume becomes currently a serious challenge for reservoir owners, against which countermeasures have to be developed. This research focuses on sediment routing using a bypass tunnel to convey sediments past a dam. By transporting sediments into the tailwater past a dam, their accumulation in the reservoir is reduced significantly. However, the global number of sediment bypass tunnels is limited primarily due to high investment and maintenance cost. The main problem of all bypass tunnels is the massive invert abrasion due to high flow velocities combined with high sediment transport rates. Therefore, VAW started two research projects to counter this problem. The main goal of the first project Layout and design of sediment bypass tunnels is to investigate the invert abrasion process by conducting hydraulic laboratory tests and to establish general design criteria for optimal flow conditions in which both sediment depositions in the tunnel are avoided and the resulting abrasion damages are kept at a minimum. The second project Optimizing hydroabrasive-resistant materials at sediment bypass tunnels and hydraulic structures investigates the hydraulic resistance of different tunnel invert materials, such as high performance concrete or cast basalt plates in prototype tests at the Solis bypass tunnel. The sediment transport measurement technique used in this project was optimized during preliminary model tests.}, language = {en} } @inproceedings{HagemannAuelAlbayraketal.2012, author = {Hagemann, M. and Auel, C. and Albayrak, I. and Boes, R.M.}, title = {Hydroabrasion in Sedimentumleitstollen}, series = {Proc. 35. Dresdner Wasserbaukolloquium. "Staubauwerke - Planen, Bauen, Betreiben", Wasserbauliche Mitteilungen Heft 47}, booktitle = {Proc. 35. Dresdner Wasserbaukolloquium. "Staubauwerke - Planen, Bauen, Betreiben", Wasserbauliche Mitteilungen Heft 47}, doi = {10.25974/fhms-15161}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-151612}, pages = {95 -- 104}, year = {2012}, abstract = {Sedimentumleitstollen leiten die sedimentreichen Hochwasserspitzen um die Tal-sperre herum in den Unterlauf des Flusses und verhindern so eine fortschreitende Verlandung des Stauraums. Aufgrund der hohen Fließgeschwindigkeiten und gro-ßen Sedimentfrachten in Umleitstollen weisen diese starke Verschleißerscheinun-gen auf, die zu hohen Unterhaltskosten f{\"u}hren. Es gibt verschiedene Konzepte um diesem Problem entgegen zu wirken. Einerseits kann der Umleitstollen hydrau-lisch optimiert werden, um die Belastung auf die Sohle zu minimieren. Auf der anderen Seite kann der Widerstand der Stollensohle verbessert werden. An der Versuchsanstalt f{\"u}r Wasserbau, Hydrologie und Glaziologie (VAW) der ETH Z{\"u}-rich werden zur Zeit zwei Forschungsarbeiten durchgef{\"u}hrt, die sich diesen zwei Aspekten widmen. In großskaligen Laborversuchen erfolgt eine systematische Untersuchung und Optimierung der maßgebenden Parameter wie Fortbewegungs-art des Sediments und Abrasionstiefe der Stollensohle. Anhand von Prototypver-suchen im neu errichteten Sedimentumleitstollen Solis in Graub{\"u}nden (Schweiz) werden die Zusammenh{\"a}nge zwischen Beanspruchung, Materialeigenschaften und Abrasion im Prototyp ermittelt. Darauf basierend k{\"o}nnen Empfehlungen be-z{\"u}glich Materialwahl, konstruktiver Durchbildung und Dimensionierung abgege-ben und so zu einer nachhaltigen und wirtschaftlichen Wasserbewirtschaftung in Stauseen beigetragen werden.}, language = {de} } @inproceedings{AuelAlbayrakBoes2014, author = {Auel, C. and Albayrak, I. and Boes, R.M.}, title = {Laborversuche {\"u}ber die Partikelbewegung in schiessendem Abfluss (Laboratory experiments on particle motion in supercritical flows)}, series = {Proc. Int. Symposium "Wasser- und Flussbau im Alpenraum", VAW Mitteilungen}, booktitle = {Proc. Int. Symposium "Wasser- und Flussbau im Alpenraum", VAW Mitteilungen}, publisher = {ETH Zurich}, pages = {147 -- 156}, year = {2014}, language = {de} }