Contents of Publ. 283

EROSION AND SEDIMENT TRANSPORT MEASUREMENT IN RIVERS: Technological and Methodological Advances edited by J. Bogen, T. Fergus & D. E. Walling IAHS Publication 283 (December 2003) ISBN 1-901502-42-2; 238 + viii pp. Price £45.50

The growing awareness of the important role of fluvial sediment in a wide range of environmental problems has accentuated the need for better and more consistent information, yet data collection in this field still lags behind other areas of hydrology. New problems call for new approaches, new strategies and new Abstracts of the methods, in order to develop an improved understanding of cause and effect relationships for different activities within a river basin. papers in this Developments in what can be measured in the field, or on samples returned to volume can the laboratory, and in how the data can be used, are moving forward apace. In the be seen at case of instream measurements, the environment is often hostile but innovative use www.iahs.info of new technology enables data collection that was previously unthought of. with information This volume comprises a selection of 24 papers from the Oslo Workshop (2002) about other IAHS of the same title. They are grouped into three topics: publications and – Suspended sediment IAHS activities – Erosion and sediment sources in catchments – Bed load monitoring and transport processes Together the papers provide both a synthesis of existing knowledge and a review of the progress of current research and development.

Contents of Publ. 283 in sediment budget investigations Sediment transport in agricultural catchments D. E. Walling —the need for methods to trace sediment sources Lillian Øygarden, Johannes Deel- 1 Suspended Sediment stra, Hans Olav Eggestad & A new definition of suspended sediment: im- Stine Marie Vandsemb plications for the measurement and predic- Application of an improved PEEP system to tion of sediment transport bank erosion investigations on the River Ian G. Droppo Wharfe, UK Damian M. Lawler Turbidity-controlled sampling for suspended Development of a sediment yield model for sediment load estimation Jack Lewis Ghana using sediment transport data Testing laser-based sensors for continuous in Mark Bambury & John Elgy situ monitoring of suspended sediment in the Suspended and bed load sediment transport Colorado River, Arizona Theodore S. Melis, dynamics in two lowland UK streams— David J. Topping & David M. Rubin storm integrated monitoring D. J. Evans, Continuous measurement of suspended-sedi- P. J. Johnes & D. S. Lawrence ment discharge in rivers by use of optical backscatterance sensors 3 Bed Load Monitoring and David H. Schoellhamer & Scott A. Wright Transport Processes Measuring suspended sediment characterist- Perspectives on bed load measurement ics using a LISST-ST in an embanked flood P. Ergenzinger & C. de Jong plain of the River Rhine Sampler size and sampling time affect bed Ivo Thonon & Marcel Van Der Perk load transport rates and particle sizes meas- Modelling and monitoring flow and suspen- ured with bed load traps in gravel-bed ded sediment transport in lowland river flood streams Kristin Bunte & Steven R. Abt plain environments The continuous monitoring of bed load flux A. P. Nicholas in various fluvial environments Jonathan B. Laronne, Yulia Alexandrov, 2 Erosion and Sediment Sources in Nathaniel Bergman, Hai Cohen, Celso Garcia, Catchments Helmut Habersack, Mark Powell & Ian Reid Using environmental radionuclides as tracers Event bed load yield measurement with load Sediment monitoring of glacial rivers in Ice- and field tests in Little Granite Creek, cell bed load traps and prediction of bed load land: new data on bed load transport Jórunn Wyoming, USA John Downing, yield from hydrograph shape D. A. Sear Hardardóttir & Árni Snorrason Paul J. Farley, Kristin Bunte, Kurt Swingle, Sandra E. Ryan & Mark Dixon An assessment of the accuracy of the Spatial Integration Method (SIM) for estimating Monitoring bed load transport using acoustic coarse bed load transport in gravel-bedded and magnetic devices Wojciech Froehlich streams using tracers Bed load measurements with a passive D. A. Sear, M. W. E. Lee, P. A. Carling, magnetic induction device R. J. Oakey & M. B. Collins Allen S. Gottesfeld & Jon Tunnicliffe Use of radio-tracking techniques in bed load Measurement of bed load with the use of transport investigations hydrophones in mountain torrents Helmut M. Habersack Takahisa Mizuyama, Masaharu Fujita & Bed load measurements with a new passive Michinobu Nonaka acoustic sensor Jim Bogen & Knut Møen An instrument to record sediment movement Acoustic gravel-transport sensor: description in bedrock channels K. Richardson, I. Benson & P. A. Carling Contents

Preface v by Jim Bogen, Tharan Fergus & Des Walling

1 Suspended Sediment

A new definition of suspended sediment: implications for the measurement and 3 prediction of sediment transport Ian G. Droppo

Turbidity-controlled sampling for suspended sediment load estimation Jack 13 Lewis

Testing laser-based sensors for continuous in situ monitoring of suspended sedi- 21 ment in the Colorado River, Arizona Theodore S. Melis, David J. Topping & David M. Rubin

Continuous measurement of suspended-sediment discharge in rivers by use of 28 optical backscatterance sensors David H. Schoellhamer & Scott A. Wright

Measuring suspended sediment characteristics using a LISST-ST in an embanked 37 flood plain of the River Rhine Ivo Thonon & Marcel Van Der Perk

Modelling and monitoring flow and suspended sediment transport in lowland 45 river flood plain environments A. P. Nicholas

2 Erosion and Sediment Sources in Catchments

Using environmental radionuclides as tracers in sediment budget investigations 57 D. E. Walling

Sediment transport in agricultural catchments—the need for methods to trace 79 sediment sources Lillian Øygarden, Johannes Deelstra, Hans Olav Eggestad & Stine Marie Vandsemb

Application of an improved PEEP system to bank erosion investigations on the 88 River Wharfe, UK Damian M. Lawler

Development of a sediment yield model for Ghana using sediment transport data 96 Mark Bambury & John Elgy

Suspended and bed load sediment transport dynamics in two lowland UK streams 103 —storm integrated monitoring D. J. Evans, P. J. Johnes & D. S. Lawrence

3 Bed Load Monitoring and Transport Processes

Perspectives on bed load measurement P. Ergenzinger & C. de Jong 113

Sampler size and sampling time affect bed load transport rates and particle sizes 126 measured with bed load traps in gravel-bed streams Kristin Bunte & Steven R. Abt The continuous monitoring of bed load flux in various fluvial environments 134 Jonathan B. Laronne, Yulia Alexandrov, Nathaniel Bergman, Hai Cohen, Celso Garcia, Helmut Habersack, D. Mark Powell & Ian Reid

Event bed load yield measurement with load cell bed load traps and prediction of 146 bed load yield from hydrograph shape D. A. Sear

Sediment monitoring of glacial rivers in Iceland: new data on bed load transport 154 Jórunn Hardardóttir & Árni Snorrason

An assessment of the accuracy of the Spatial Integration Method (SIM) for estim- 164 ating coarse bed load transport in gravel-bedded streams using tracers D. A. Sear, M. W. E. Lee, P. A. Carling, R. J. Oakey & M. B. Collins

Use of radio-tracking techniques in bed load transport investigations 172 Helmut M. Habersack

Bed load measurements with a new passive acoustic sensor Jim Bogen & 181 Knut Møen

Acoustic gravel-transport sensor: description and field tests in Little Granite 193 Creek, Wyoming, USA John Downing, Paul J. Farley, Kristin Bunte, Kurt Swingle, Sandra E. Ryan & Mark Dixon

Monitoring bed load transport using acoustic and magnetic devices 201 Wojciech Froehlich

Bed load measurements with a passive magnetic induction device 211 Allen S. Gottesfeld & Jon Tunnicliffe

Measurement of bed load with the use of hydrophones in mountain torrents 222 Takahisa Mizuyama, Masaharu Fujita & Michinobu Nonaka

An instrument to record sediment movement in bedrock channels 228 K. Richardson, I. Benson & P. A. Carling

Key word index 237 v

Preface

Due to a growing awareness of the important role of fluvial sediment in a wide range of environmental problems, there is an increasing need for a better understanding of the processes of erosion and sedimentation, and their impact on the transport of sediment in rivers. Despite of the need for better and more consistent information, data collection in this field still lags behind other areas of hydrology. New problems also call for new approaches, new strategies and new methods, in order to develop an improved understanding of cause and effect relationships for different activities within a river basin. Over the years, the IAHS International Commission on Continental Erosion (ICCE) has organized a number of symposia dealing with different aspects of erosion and sedimentation. Some of these have focused on measurement techniques within the field. These are the symposia held in Florence in 19811 on Erosion and Sediment Transport Measurement, and that held in Oslo in 19922 on Erosion and Sediment Transport Monitoring Programmes in River Basins. The Workshop held in Oslo during 19–21 June 2002, on Erosion and Sediment Transport Measurement: Technological and Methodological Advances, followed up this focus on measurement techniques and directed particular attention to the development of new sediment measurement technologies. The 24 papers published in this volume are a selection of those presented at the Workshop. They provide both a synthesis of existing knowledge and a review of the status of current research and development in this field. The papers have been grouped under three main themes. The first group includes six papers that deal with suspended sediment. One introductory paper discusses a new definition of suspended sediment and its implication for the measurement and prediction of suspended sediment transport. The following five papers present valuable results from studies aimed at testing optical- and laser-based sensors for monitoring suspended sediment concentrations and grain size distributions, using turbidity meters to control suspended sediment sampling programmes, and collecting detailed information on flow velocities for use in modelling the suspended sediment dynamics of floodplain systems. The five papers in the second group deal with erosion and sediment sources in catchments. One paper examines recent developments in the use of environmental radionuclides as tracers in the study of catchment sediment budgets. Another contribution explores the potential for identifying the possible sources and transfer pathways of the suspended sediment output from a small catchment, whilst a third focuses on a single sediment source and describes recent advances in the automated monitoring of bank retreat. The last two papers in this group discuss the development of a model for estimating suspended sediment yields and the monitoring of suspended

1 Erosion and Sediment Transport Measurement (1981) (Proc. Symp., Florence, June 1981). IAHS Publ. 133. 2 Erosion and Sediment Transport Monitoring Programmes in River Basins (1992) (ed. by J. Bogen, D. E. Walling & T. J. Day) (Proc. Symp, Oslo, August 1992). IAHS Publ. 210. sediment and bed load transport dynamics. The 13 papers in the third group deal with bed load monitoring and associated transport processes. A review paper provides an overview of bed load measurements, and four further papers report recent developments in bed load sampling involving bed load traps and basket samplers, and in the continuous monitoring of bed load flux using load cells. Two papers discuss the use of tracing and radio tracking techniques and the final six papers report results from tests of various types of bed load sensors aimed at assessing their ability to measure bed load flux in rivers. It is hoped that publication of these presentations from the Oslo Workshop will stimulate further discussion and draw attention to recent advances in erosion and sediment transport measurement involving new methods and new technologies.

Editor in chief: Jim Bogen Norwegian Water Resources and Energy Directorate (NVE)

Co-editors: Tharan Fergus Norwegian Water Resources and Energy Directorate Des Walling Department of Geography, University of Exeter, UK

Financial support for the Workshop, and for the preparation of the publication, from the Norwegian Water Resources and Energy Directorate(NVE) is gratefully appreciated.

The Editors would like to express special thanks to everyone who helped with the organization of the Workshop and production of this proceedings volume, in particular Evy Vollmo from NVE, and Penny Farnell and Cate Gardner from IAHS Press in Wallingford. Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002). IAHS Publ. 283, 2003, p. 3–12. A new definition of suspended sediment: implications for the measurement and prediction of sediment transport

IAN G. DROPPO National Water Research Institute, Environment Canada, PO Box 5050, Burlington, Ontario L7R 4A6, Canada [email protected]

Abstract Sediment (floc) structure is discussed in relation to its influence on the measurement and prediction of sediment transport. Structural characteristics of floc size, porosity, density and compositional matrix are investigated with the aim of creating a new paradigm of suspended sediment. This new paradigm is intended to influence the development of new techniques and strategies for the quantification of suspended sediment transport in aquatic environments. Key words deposition; floc; flocculation; suspended sediment; transport

______Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002). IAHS Publ. 283, 2003, p. 13–20. Turbidity-controlled sampling for suspended sediment load estimation

JACK LEWIS USDA Forest Service, Pacific Southwest Research Station, 1700 Bayview Dr., Arcata, California 95521, USA [email protected]

Abstract Automated data collection is essential to effectively measure suspended sediment loads in storm events, particularly in small basins. Continuous turbidity measurements can be used, along with discharge, in an automated system that makes real-time sampling decisions to facilitate sediment load estimation. The Turbidity Threshold Sampling method distributes sample collection over the range of rising and falling turbidity values and attempts to sample all significant turbidity episodes. A data logger activates a pumping sampler when specified turbidity conditions are met. The resulting set of samples can be used to accurately determine suspended sediment loads by establishing a relation between sediment concentration and turbidity for any sampled period with significant sediment transport. Relations between turbidity, concentration, and particle size are examined at five sites in northern California, USA. Despite the influence of particle size, turbidity is in all cases superior to flow as a surrogate for sediment concentration. Key words particle size; regression; sampling; suspended sediment; turbidity

______Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002). IAHS Publ. 283, 2003, p. 21–27. Testing laser-based sensors for continuous in situ monitoring of suspended sediment in the Colorado River, Arizona THEODORE S. MELIS, DAVID J. TOPPING US Geological Survey, Grand Canyon Monitoring & Research Center, 2255 N. Gemini Dr., Flagstaff, Arizona 86001, USA [email protected]

DAVID M. RUBIN US Geological Survey, Coastal & Marine Geology, Santa Cruz, California 95064, USA

Abstract High-resolution monitoring of sand mass balance in the Colorado River below Glen Canyon Dam, Arizona, USA, is needed for environmental management. In the Grand Canyon, frequent collection of suspended-sediment samples from cableways is logistically complicated, costly and provides limited spatial and temporal resolution. In situ laser sensors were tested in the Colorado River as an alternative method for monitoring the river’s suspended transport. LISST data were collected at a fixed-depth, near-shore site while isokinetic measurements were simultaneously made from a nearby cableway. Diurnal variations in LISST grain size and concentration data compared well with depth-integrated, cross-section data. The LISST was also successfully used to electronically trigger an ISCO 6712 pump sampler to provide continuous monitoring during periods when suspended concentrations exceeded the LISST’s measurement range. Initial results indicate that the LISST can provide useful high-resolution suspended-sediment data within the Colorado River, when optics are maintained on a weekly basis. Key words Colorado River; environmental monitoring; LISST; suspended-sediment transport

______Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002). IAHS Publ. 283, 2003, p. 28–36.

Continuous measurement of suspended-sediment discharge in rivers by use of optical backscatterance sensors

DAVID H. SCHOELLHAMER & SCOTT A. WRIGHT US Geological Survey, Placer Hall, 6000 J Street, Sacramento, California 95819, USA [email protected]

Abstract Optical sensors have been used to measure turbidity and suspended-sediment concentration by many marine and estuarine studies, and optical sensors can provide automated, continuous time series of suspended-sediment concentration and discharge in rivers. Three potential problems with using optical sensors are biological fouling, particle-size variability, and particle-reflectivity variability. Despite varying particle size, output from an optical backscatterance sensor in the Sacramento River at Freeport, California, USA, was calibrated successfully to discharge-weighted, cross-sectionally averaged suspended-sediment concentration, which was measured with the equal discharge-, or width-increment, methods and an isokinetic sampler. A correction for sensor drift was applied to the 3-year time series. However, the calibration of an optical backscatterance sensor used in the Colorado River at Cisco, Utah, USA, was affected by particle-size variability. The adjusted time series at Freeport was used to calculate hourly suspended-sediment discharge that compared well with daily values from a sediment station at Freeport. The appropriateness of using optical sensors in rivers should be evaluated on a site-specific basis and measurement objectives, potential particle size effects, and potential fouling should be considered. Key words Colorado River; equal discharge increment method; isokinetic sampling; optical backscatterance sensor; particle size; Sacramento River; suspended sediment; suspended-sediment discharge

Measuring suspended sediment characteristics using a LISST-ST in an embanked flood plain of the River Rhine

IVO THONON & MARCEL VAN DER PERK Centre for Geo-ecological Research (ICG), Faculteit Ruimtelijke Wetenschappen, Universiteit Utrecht, Postbus 80115, 3508 TC, Utrecht, The Netherlands [email protected]

Abstract During two inundation periods in Spring 2002, we deployed a combined particle sizer and settling tube on an embanked flood plain along the River Waal (mean discharge = 2400 m 3 s–1) in the eastern part of The Netherlands. This so-called LISST-ST device uses laser diffraction principles to measure in situ grain size distribution, settling velocities and concentrations of the suspended matter in the inundation water. To verify these measurements, we manually collected water samples and deployed an optical backscatter sensor to measure total sediment concentration and turbidity, respectively. The measurements revealed that the grain size distribution and suspended sediment concentration depend on the discharge, while the settling velocity does not vary with discharge, but depends on flocculation processes. In the near future, in situ measured sediment characteristics will be compared to those from sediment retained in sediment traps located in the same flood plain. Key words flocculation; flood plain; grain size; laser diffraction; River Rhine; settling velocity; suspended sediment

Modelling and monitoring flow and suspended sediment transport in lowland river flood plain environments

A. P. NICHOLAS Department of Geography, University of Exeter, Exeter, Devon EX4 4RJ, UK [email protected]

Abstract This paper examines the potential for investigating flow and suspended sediment transport mechanisms on lowland flood plains using a combination of three-dimensional numerical modelling and acoustic Doppler velocimetry. Model results show that, contrary to the common perception that suspended sediment transport is controlled predominantly by turbulent mixing processes, horizontal sediment exchanges between the channel and flood plain are largely a product of advection along topographically determined flow lines. Modelled and monitored profiles of time-averaged flow illustrate that vegetative roughness promotes characteristic velocity and turbulent kinetic energy profiles that contrast markedly with the logarithmic “law of the wall”. Instantaneous velocity and sediment concentration data obtained at a high sampling frequency confirm that while horizontal sediment transport is dominated by advection, the vertical sediment concentration profile in the lower half of the flow is controlled strongly by the balance between turbulent ejection and sweep events. Key words acoustic Doppler velocimeter; flood plain; numerical model; suspended sediment ______Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002). IAHS Publ. 283, 2003, 57–78.

Using environmental radionuclides as tracers in sediment budget investigations

D. E. WALLING Department of Geography, University of Exeter, Exeter EX4 4RJ, UK [email protected] Abstract The many problems associated with the presence of fine sediment in river basins has generated an increasing need for an improved understanding of the mobilization, transfer and fate of such sediment, in order to plan appropriate sediment management and control strategies. The sediment budget concept affords a valuable framework for assembling information on the sediment response of a catchment, but it is difficult to assemble the data required to construct a reliable sediment budget. The use of environmental or fallout radionuclides offers considerable potential for developing improved understanding and characterization of catchment sediment budgets. The basis for using caesium-137, unsupported lead-210 and beryllium-7 as tracers in sediment budget investigations is outlined, and examples of the use of these radionuclides in studies of soil erosion and sediment delivery from agricultural land, flood plain sedimentation and associated sediment conveyance losses, and sediment source fingerprinting are provided. Key words environmental radionuclides; flood plain sedimentation; sediment budget; sediment delivery; sediment tracing; soil erosion

Sediment transport in agricultural catchments—the need for methods to trace sediment sources

LILLIAN ØYGARDEN, JOHANNES DEELSTRA, HANS OLAV EGGESTAD & STINE MARIE VANDSEMB Jordforsk, Centre for Soil and Environmental Research, Frederik A. Dahlsvei 20, 1432 Ås, Norway [email protected]

Abstract In the Agricultural Environmental Monitoring Programme (JOVA) runoff, losses of suspended solids and nutrients are measured. In the Skuterud (680 ha) and Mørdre (450 ha) catchments, soil erosion from agricultural land is considered to be the major source of particles. Information about agricultural practices on each field is collected to relate losses of particles to e.g. the area ploughed at the time of runoff. In spite of there being less area tilled than normal in the autumn 2000, soil losses were M higher than mean values for the 10-year monitoring period (1991/1993–2001). Autumn precipitation was 2–3 times higher and runoff 3–5 times higher than normal. A field inventory documented that not only tillage contributed to soil losses, but also preferential flow, erosion around hydrotechnical installations and especially bank erosion. It illustrates the need to have methods for tracing all sources of sediment for the planning of conservation measures. Key words catchment; environment; erosion; monitoring; Norway; nutrient losses; runoff; tracers

Application of an improved PEEP system to bank erosion investigations on the River Wharfe, UK

DAMIAN M. LAWLER School of Geography, Earth and Environmental Sciences, The University of Birmingham, Birmingham B15 2TT, UK [email protected]

Abstract Knowledge of erosion event timing, frequency and magnitude, in relation to fluctuations in the driving forces, is vital to strong hydrological and geomorphological process inference. However, traditional manual monitoring techniques simply reveal net, temporally- lumped, change to the eroding surface since the previous measurement. This paper briefly reviews the original Photo-Electronic Erosion Pin (PEEP) system developed to collect data on the timing, frequency and magnitude of erosional and depositional events. The PEEP system allows, for the first time, the vital automatic monitoring of erosion and deposition events. The paper then briefly tabulates some of the recent improvements to the PEEP system. These are principally designed to generate even more accurate erosion event timing data, and facilitate monitoring of site thermal conditions. Results from the River Wharfe show how the modified PEEP-3 system can: (a) pinpoint more accurately the timing of bank retreat events with respect to the hydrograph (2 h before the flow peak on the Wharfe example here); (b) quantify the erosional impact of individual, rather than aggregated, flow events; (c) clarify the frequency and intensity of on-site bank freeze-thaw cycles; and (d) help to suggest or eliminate the likely bank destabilising processes. Eighteen research groups around the world now use the new PEEP-3 system. Key words bank erosion; bank retreat events; bank temperature; flow events; freeze-thaw cycles; PEEP system; River Wharfe; Thermal Consonance Timing

______Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002). IAHS Publ. 283, 2003, 96–102.

Development of a sediment yield model for Ghana using sediment transport data

MARK BAMBURY & JOHN ELGY Department of Civil Engineering, Aston University, Aston Triangle, Birmingham B4 7ET, UK [email protected]

Abstract Soil erosion is one of the most pressing issues facing developing countries. In Ghana, a country with an expanding population and high potential for economic growth, agriculture is an important resource. The high intensity seasonal rainfall coincides with the early growing period of crops such as maize, yam and cassava. Agricultural plots are very susceptible to high erosion rates, especially when on steep sided valleys in the region around the south of Lake Volta. Thus, accurate prediction of soil erosion is a necessity. The accuracy of soil erosion models is largely determined by the availability and quality of the sediment yield data used for calibration. A conceptual model based on the CALSITE model is being developed to run in the GRASS GIS package for use in Ghana. The model is being tested on a 14 km2 basin southwest of Lake Volta, where streamflow, rainfall, soil moisture and sediment transport data were collected during September 2000. Key words CALSITE; conceptual modelling; Ghana; sediment transport; sediment yield; soil erosion

Development of a sediment yield model for Ghana using sediment transport data

MARK BAMBURY & JOHN ELGY Department of Civil Engineering, Aston University, Aston Triangle, Birmingham B4 7ET, UK [email protected]

Abstract Soil erosion is one of the most pressing issues facing developing countries. In Ghana, a country with an expanding population and high potential for economic growth, agriculture is an important resource. The high intensity seasonal rainfall coincides with the early growing period of crops such as maize, yam and cassava. Agricultural plots are very susceptible to high erosion rates, especially when on steep sided valleys in the region around the south of Lake Volta. Thus, accurate prediction of soil erosion is a necessity. The accuracy of soil erosion models is largely determined by the availability and quality of the sediment yield data used for calibration. A conceptual model based on the CALSITE model is being developed to run in the GRASS GIS package for use in Ghana. The model is being tested on a 14 km2 basin southwest of Lake Volta, where streamflow, rainfall, soil moisture and sediment transport data were collected during September 2000. Key words CALSITE; conceptual modelling; Ghana; sediment transport; sediment yield; soil erosion

Perspectives on bed load measurement

P. ERGENZINGER Berlin–Bonn Environmental Research Group, Bornheimerstr. 2, D-53332 Uedorf, Germany [email protected]

C. DE JONG Department of Geography, University of Bonn, D-53001 Bonn, Germany

Abstract Over the past decade there have been important developments in bed load measurement techniques for floods and debris flows in mountain areas. While suspended sediment is still the more common fraction measured, bed load remains a problem since it is not only more difficult to measure but it also causes most impact in terms of geomorphological change. Developments in field measuring techniques for bed load transport are essential and require sophistication in order to function efficiently in different environments. Optimally, bed load measuring techniques should be non-intrusive, flexible and representative for different types of transport. This contribution is the result of several decades of bed load experiments in mountain torrents focused on gravel- and cobble-bed streams and problems of developing bed load measuring approaches and devices for future application. Techniques of trapping and tracing are described and the potential of high-resolution remotely sensed images are stressed. The increasing awareness of bed dynamics and changes in gravel-bed rivers will create a growing demand for reliable field data for use in further model validation and application. Key words acoustic detectors; bed load measurement; image analysis; radio tracing; samplers; tracers; traps; visual tracers

Sampler size and sampling time affect bed load transport rates and particle sizes measured with bed load traps in gravel-bed streams

KRISTIN BUNTE & STEVEN R. ABT Engineering Research Center, Colorado State University, Fort Collins, Colorado 80523, USA [email protected]

Abstract A bed load trap was designed for collecting gravel and cobble bed load and tested in four mountain gravel-bed streams. The traps permit a long sampling duration of about 1 h and have a large 0.3 × 0.2 m opening as well as a large sampler bag. Samples collected with the bed load traps have well-defined power-function bed load rating curves with exponents of 8– 16. Compared to a Helley-Smith sampler with a 7.6 × 7.6 cm opening, bed load transport measured with the traps is smaller during low flows and larger during high flows. Bed load particle-size distributions obtained with the traps coarsen more pronouncedly with flow than those obtained with a Helley-Smith sampler. These differences in sampled bed load transport rates and size distributions have implications for computations such as critical discharge, annual load, and effective discharge. Key words bed load sampling; bed load traps; flow competence; gravel bed load transport; initial motion; rating curve; Rocky Mountain gravel-bed rivers; sampling time

The continuous monitoring of bed load flux in various fluvial environments

JONATHAN B. LARONNE1, YULIA ALEXANDROV1, NATHANIEL BERGMAN1, HAI COHEN1, CELSO GARCIA2, HELMUT HABERSACK3, D. MARK POWELL4 & IAN REID5 1 Department of Geography and Environmental Development, Ben Gurion University of the Negev, Beer Sheva 84105, Israel [email protected] 2 Department of Earth Sciences, University of the Balearic Islands, Palma de Mallorca 07071, Spain 3 Department for Water Management, Hydrology and Hydraulic Engineering, Universitaet fuer Bodenkultur, Muthgasse 18, 1190 Vienna, Austria 4 Department of Geography, University of Leicester, Leicester LE1 7RH UK 5 Department of Geography, Loughborough University, Loughborough, LE11 3TU, UK

Abstract We present detailed advantages and limitations of an accurate, reliable, durable and relatively cheap means of continuously monitoring bed load flux and texture using Birkbeck- type slot samplers based on almost a quarter of a century of data. These have been derived from alpine, mid-latitude perennial, Mediterranean, semiarid, and arid fluvial settings in rivers 1–40 m wide that have characteristic surface bed materials in the sand-granule to cobble range. Methods of construction and principles of operation, calibration, data handling, ranges of flux rates and textural characteristics of bed load are discussed. Key words bed load flux; cessation of motion; incipient motion; sampling; texture

Event bed load yield measurement with load cell bed load traps and prediction of bed load yield from hydrograph shape

D. A. SEAR Department. of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK [email protected] Abstract One of the goals of sediment transport research is to predict the bed load yield of ungauged catchments. However, what little field data exist are characterized by temporal fluctuations in the record of event yield. Attempts to model the process of transport typically involve the derivation of empirical relationships between commonly measured variables such as stream discharge and the rate of bed load transport. Such approaches fail to account for the effect of sediment supply on the process of transport, which is known to contribute to the variability in records. This paper sets out a conceptual model of sediment transport that establishes a link between the form of the stream hydrograph and the effectiveness of an event as indexed by sediment yield. The model is then tested against a dataset of 60 bed load transport events recorded using a new type of load-cell pit trap. Total event power is shown to be capable of explaining 70% of the variance in event yields for a small woodland stream. Key words bed load yield; event duration; sediment supply; stream hydrograph

Sediment monitoring of glacial rivers in Iceland: new data on bed load transport

JÓRUNN HARDARDÓTTIR & ÁRNI SNORRASON Hydrological Service, Orkustofnun, Grensásvegur 9, IS-108, Iceland [email protected]

Abstract Sediment monitoring of glacial rivers in Iceland has been carried out at the Hydrological Service of the National Energy Authority during the past five decades. This paper describes the expansion of the monitoring in recent years, with special emphasis on recent bed load sampling. As an example, the results from an extensive sediment sampling project in the harnessed glacial river Thjórsá, south Iceland, are discussed and compared with results from three other glacial rivers (Skaftá in south Iceland and Jökulsá á Fjöllum and Jökulsá á Dal in north and northeast Iceland) where bed load studies were carried out in 2001. Great changes in “at-a-point” bed load rate measured with a Helley-Smith sampler are seen among the four rivers, and variability within individual channels and sampling campaigns at diverse river discharge is prominent. Mean total bed load discharge for an individual sampling campaign was lowest in Thjórsá (0.03 kg s-1 m-1) and highest in a June campaign in Jökulsá á Dal (1.58 kg s-1 m-1). The mean total bed load transport rates in this study are higher than many published rates for arctic and alpine environments. Key words bed load transport; glacial rivers; Iceland; jökulhlaup; suspended sediment load

An assessment of the accuracy of the Spatial Integration Method (SIM) for estimating coarse bedload transport in gravel-bedded streams using tracers

D. A. SEAR, M. W. E. LEE, P. A. CARLING Department of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK [email protected]

R. J. OAKEY Department of Geography, University of Lancaster, Bailrigg, Lancaster LN14 2LX, UK

M. B. COLLINS School of Ocean & Earth Science, University of Southampton, Southampton Oceanography Centre, European Way, Southampton SO14 3ZH, UK

Abstract The accurate estimation of coarse sediment transport rate remains one of the goals of geomorphological and engineering studies of river channels. This paper describes an experiment designed to assess the accuracy of the Spatial Integration Method (SIM) of determining sediment transport rate or yield, using passive tracers. Tracer dispersion results are presented from five events of different magnitude. The study concludes that the SIM is capable of producing estimates of sediment transport rate that correspond with trapped values. Sources of error are quantified and guidance is given on the appropriate methods for deploying passive tracers for the estimation of coarse sediment transport rates. Key words sediment transport rate; spatial integration method; tracers

Use of radio-tracking techniques in bed load transport investigations

HELMUT M. HABERSACK Department of Water Management, Hydrology and Hydraulic Engineering, Universitaet fuer Bodenkultur Vienna, Muthgasse 18, 1190 Vienna, Austria [email protected] Abstract This paper aims to analyse the use of radio-tracking techniques in bed load transport investigations. The Lagrangian technique of radio-tracking offers the opportunity to investigate the stochastic elements of transport, from erosion to final deposition after a flood. It consists of a swinging quartz in transmitters, antennae and receivers, and computer/software for storing data and controlling the measurements. The technique is shown to be useful for analysing the interaction between flow turbulence and initiation of motion, bed particle dispersion, distribution of step lengths and rest periods, as well as the interaction between morphology and transport paths. Key words bed load transport; gravel bed rivers; river morphology

Bed load measurements with a new passive acoustic sensor

JIM BOGEN & KNUT MØEN Norwegian Water Resources and Energy Directorate (NVE), PO Box 5091 Maj.,N-0301 Oslo, Norway [email protected]

Abstract Flume experiments and field tests of acoustic bed load sensors have been carried out in three Norwegian rivers. The sensors record the acoustic energy of bed load impacts on a plate fixed to the river bed. Some of the sensors operate in a narrow ultrasonic frequency band, while others record the whole frequency spectrum from 0 to 500 kHz. The systems tested are able to monitor temporal variations in bed load transport and thereby provide additional information about the transport process. The field measurements revealed a markedly irregular pattern of bed load transport rates. The presence of a hysteresis effect indicates some similarity to suspended load transport, with the transport rate being much larger on the rising stage of a flood than on the falling stage. A large difference between maximum and mean acoustic amplitudes over a given time period reflects sporadic transport; the difference is much less when particle transport is continuous. Flume experiment results for a single fraction, 18–27 mm, produced a linear relationship between bed load transport in kg s-1 and acoustic energy integrated over the frequency range. Preliminary analyses indicate that a characteristic relationship exists for each size fraction within the bed load range. The present studies of the transport of different grades also indicate that each fraction may have a characteristic frequency signature. Thus, it is possible that a multivariate calibration model may predict both total load and grain size from acoustic amplitudes and frequency spectra. Key words bed load; chemometric; field tests; flume experiment; frequency signature; Norway; passive acoustic sensor; sediment

______Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002). IAHS Publ. 283, 2003, p. 193–200 Acoustic gravel-transport sensor: description and field tests in Little Granite Creek, Wyoming, USA

JOHN DOWNING1, PAUL J. FARLEY1, KRISTIN BUNTE2, KURT SWINGLE3, SANDRA E. RYAN4 & MARK DIXON4

1 D & A Instrument Company, 40-A Seton Road, Port Townsend, Washington 98368, USA [email protected] 2 Engineering Research Center, Colorado State University, Fort Collins, Colorado 80523, USA 3 630 Iris Avenue, Boulder, Colorado 80304, USA 4 US Forest Service, Forestry Sciences Laboratory, Laramie, Wyoming 82070, USA

Abstract Acoustic systems have been developed for the measurement of bed load momentum in gravel bed streams. The transducers are placed in the bed load either by a wading operator (GTS-I) or in a fixed installation embedded in the stream (GTS-II). The signals produced when particles impact the transducer are processed by an electronics unit to provide a continuous record of bed load momentum. A recent comparison of a GTS-II system with bed load traps in a small, mountain stream yielded promising results. Although the data are limited, they show that when the size of the bed load is known, corrections for grain velocity are made, and time- space averaging is sufficient, GTS measurements are roughly comparable to those made with bed load traps. Key words bed load; bed load transport; gravel bed streams; gravel-transport sensor

Monitoring bed load transport using acoustic and magnetic devices

WOJCIECH FROEHLICH Homerka Laboratory of Fluvial Processes, Institute of Geography and Spatial Organization, Polish Academy of Sciences, Frycowa 113, 33-335 Nawojowa, Poland [email protected]

Abstract The work reported was undertaken in the Homerka instrumented catchment in the Polish Flysch Carpathians, where different techniques for monitoring coarse sediment transport have been applied over the past 30 years. The area is characterized by highly active erosion, sediment transport and fluvial sedimentation processes. Bed load transport has been measured using both acoustic and magnetic techniques. The acoustic (hydrophone) method permits continuous measurement and is able to provide a continuous record of coarse particle movement during flood events, which is a direct reflection of the magnitude of bed load movement. In general, bed load transport reaches a peak more rapidly than the water discharge. For a given flood discharge, the intensity of bed load transport varies between the rising and falling stages of a flood event. Coarse material bed load transport has also been measured in the Homerka catchment using magnetic tracers. In this case, magnets are cemented into holes drilled into gravel particles and an electromagnetic sensor is used to track their movement through a designated short reach. In addition, transport distances associated with individual gravel particles tagged with magnets during individual events have been documented by recovering the labelled gravel after the event using a metal detector. These magnetic tracing techniques permit the bed load transport rate associated with individual grain size fractions to be quantified. Key words acoustic device; bed load transport; hydrophone; magnetic device; mountain streams; Polish Carpathians; sediment transport

Bed load measurements with a passive magnetic induction device

ALLEN S. GOTTESFELD Gitxsan Watershed Authorities, Hazelton, British Columbia V0J 1Y0, Canada [email protected]

JON TUNNICLIFFE Geography Department, University of British Columbia, Vancouver, British Columbia V6T 1W5, Canada

Abstract The Bed load Movement Detector (BMD) is installed on the O’Ne-ell Creek, a gravel bed stream, with a forced pool-riffle morphology, in the upper Fraser River basin in northern British Columbia, Canada. The device records the passage of individual particles across the full width of the channel. At the peak of the 1999 nival flood sediment movement, approximately 3 × 105 particle passages per hour were detected. The transport rate increases as the stage and water discharge increase. Bed load movement in this flood involved nearly all of the stream bed, but the point of most intense transport varied across the channel throughout the flood. During one week of flood discharge, 14.41 × 106 particles were recorded passing the BMD. We estimate that this is approximately equivalent to 7.88 m3. Pulses of sediment movement are apparent at a variety of time scales ranging from diurnal to seconds. While the spasmodic character of the sediment transport is most pronounced at scales of 5 min to 1 h, there is no stable periodicity in the record. Key words bed load; bed load movement sensors; fluvial geomorphology; gravel bed streams; pool-riffle morphology

Measurement of bed load with the use of hydrophones in mountain torrents

TAKAHISA MIZUYAMA Division of Forest Science, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan m izuyama @kais.kyoto-u.ac.jp

MASAHARU FUJITA Disaster Prevention Research Institute, Kyoto University, Kyoto 611-0011, Japan MICHINOBU NONAKA HydroTech Co., Kouzukeda 876, Hino-cho, Gamou-gun, Shiga 529-1642, Japan

Abstract Sediment transport in mountain torrents is more affected by sediment production such as landslides, bank erosion and torrent bed erosion, than by water runoff. Therefore sediment transport rate cannot be estimated theoretically using sediment transport equations. This is why we have to measure sediment transport rate in the field in the mountain torrents. Wash load and suspended load can be measured using various kinds of samplers, whereas the direct measurement of bed load is difficult. Bed load samplers that have been used in mild rivers are not applicable in mountain torrents where the flow velocity is high and the bed surface is rough. Hydrophones are more appropriate for mountain torrents. Steel pipes are installed on torrent beds or on the spillways of sabo (erosion and sediment control) dams. The number of times that sand and gravel particles hit the pipes are counted by the microphones. This system has worked well in mountain torrents. The measurement system, some observed results and preliminary analysis are reported. Key words bed load; hydrophones; measurement; mountain torrent

An instrument to record sediment movement in bedrock channels

K. RICHARDSON1, I. BENSON2 & P. A. CARLING3

1 Department of Geography, Lancaster University, Lancaster LA1 4YB, UK 2 151 Sidney Grove, Newcastle NE4 5PE, UK 3 Department of Geography, Highfield, University of Southampton SO17 1BJ, UK [email protected]

Abstract High energy bedrock channels pose particular practical difficulties in the measurement of bed load transport. An instrument has been developed to address these problems which detects the acceleration of a steel plate fixed to a rock riverbed upon being struck by a clast, and counts the impacts. The instrument has been shown to be reliable in the extreme environment presented by bedrock channels, and to provide high quality data. Three bed load sensors were deployed simultaneously in a cross section of a bedrock channel over a period of 50 days. The data obtained show that bed load is routed along well defined narrow areas of the channel. The threshold of initial motion is variable between events, while that for cessation is more constant. Within each event, bed load transport rates are hysteretic, with a higher threshold for initiation of motion than for cessation. Transport rates show strong general trends and they exhibit stochastic behaviour, demonstrating the pulsing of bed load. Key words abrasion; bed load; bedrock channel; critical shear stress; impact sensor; northwest England; sediment transport