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SEDIMENT BUDGETS 1 & 2

A pair of edited proceedings were produced for an IAHS ICCE symposium co-sponsored by UNESCO, held in April 2005 at Foz do Iguaçu, Brazil, a contribution to the International Sedimentation Initiative (ISI) of the UNESCO International Hydrological Programme (IHP VI). The contents of both are listed overleaf; the preface and abstracts of the papers in each can be seen at www.iahs.info.

A sediment budget provides an integrated view of the sediment sources, transfers, sinks and outputs of a drainage basin, and in so doing draws together the many different aspects of erosion, and sediment mobilization, transport, storage, and yield. Several key developments have influenced recent sediment budget investigations:

– increasing awareness of the environmental implications of increased sediment loads in rivers and of the need for effective sediment management and control strategies.

– advances in the techniques and models available for establishing and predicting catchment sediment budgets including use of 137Cs, 210Pb and 7Be as sediment tracers; continuous recording of suspended sediment flux; application of distributed modelling, remote sensing, and GIS

– recognition of the need to quantify sediment-associated chemical fluxes.

The papers reviewed and edited for these volumes exemplify these developments internationally.

Sediment Budgets 1 Edited by Des E. Walling & Arthur J. HorowitzPubl. 291 (2005)ISBN 1-901502-87-2; + 372 + xii pp. Price £63.00

Volume 1 focuses on the main components of the sediment budget:

– Sediment mobilization and sources – Sediment transport and transfer – Sediment storage – Sediment yields

Sediment Budgets 2 Edited by Arthur J. Horowitz & Des E. Walling Publ. 292 (2005) ISBN 1-901502-92-9; + 358 + xii pp. Price £63.00

Volume 2 emphasizes the value of sediment budgets in providing an integrating framework, for both scientific in-vestigations and environmental management:

– Sediment budgets – Modelling sediment budgets and their components – Human impact on sediment budgets – Sediment problems and sediment management strategies

Contents

Preface by Des E. Walling & Arthur J. Horowitz v

1 Sediment Mobilization and Sediment Sources

The sediment budgets of cultivated slopes and slope catch-ments: an evaluation of the influence of slope morphology Valentin Golosov & Leonid Litvin

3

Human-accelerated soil redistribution within an intensively cultivated dry valley catchment in southern European Russia Vladimir R. Belyaev, Valentin N. Golosov, Nadezhda N. Ivanova, Maxim V. Markelov & Elvira V. Tishkina

11

Etude du ruissellement et du transport solide dans les Monts de Beni-Chougrane, Algérie: utilisation de la simulation de pluie Mohamed Meddi, Yahia Boukhari & Bouddkhil Morsli

21

Sediment production by landslides in Hong Kong: two case studies M. R. Peart, J. P. King & M. E. Ruse

29

Post-eruption sediment budget of a small catchment on the Miyakejima volcano, Japan Satoshi Tagata, Takao Yamakoshi, Yasuhiro Doi, Katsuo Sasahara, Haruo Nishimoto & Hiroshi Nagura

37

The organic carbon dynamics of a small catchment in the humid tropics J. R. Ndam-Ngoupayou, J. L. Boeglin, J. L. Probst, J. J. Braun, M. Meybeck & G. Nkoue Ndondo

46

Contributions of authigenic iron compounds to fluvial suspended sediment concentrations and fluxes in the Nete sub-basin, Belgium Elin Vanlierde, Jan De Schutter, Joris F. A. Meys, Frank Mostaert & Patric Jacobs

54

A comparison of erosion rates obtained using the 137Cs technique and direct measurements on runoff plots Vladia Correchel, Osny Oliveira Santos Bacchi, Isabella Clerici De Maria, Sonia Carmella Falci Dechen & Klaus Reichard

64

The pattern of soil redistribution along a transect in the central Ebro basin (NE Spain) and its controls Ana Navas, Desmond E. Walling, Timothy A. Quine, Javier Machin & Jesus Soto

70

Interpreting 137Cs depth profiles with no single peak in lake deposits in China Xinbao Zhang, Xiubin He & Yongqing Qi

78

Riverbank erosion and its importance to uncertainties in large-scale sediment budgets Ronald De Rose, David J. Wilson, Rebecca Bartley & Scott Wilkinson

85

Identification of sediment sources in a small grazed Sahelian catchment, Burkina Faso Harouna Karambiri & Olivier Ribolzi

93

Using environmental radionuclides to elucidate sediment sources within a small drainage basin in the Polish Flysch Carpathians Wojciech Froehlich & Des E. Walling

102

Investigating sediment sources within a small catchment in southern Italy Paolo Porto, Des E. Walling & Giovanni Callegari

113

Suspended sediment sources in British rivers D. E. Walling & A. L. Collins 123

Fluvial contribution to the sediment budget of the Tay Estuary, Scotland, assessed using mineral magnetic fingerprinting Pierre A. Jenkins, Robert W. Duck & John S. Rowan

134

2 Sediment Transport and Transfer

Impacts of wildfire on effective sediment particle size: implica-tions for post-fire sediment budgets William H. Blake, Ian G. Droppo, Peter J. Wallbrink, Stefan H. Doerr, Richard A. Shakesby & Geoffrey S. Humphreys

143

Estimation of the concentration of suspended solids in rivers from turbidity measurement: error assessment Edmilson Costa Teixeira & Paulo Cezar Caliari

151

Transport des matières en suspension au Cameroun dans un contexte hydroclimatique déficitaire Gaston Lienou, Gil Mahé, Eric Servat, Rodrigue Tegofack, Joseph Sahagu, Jacob Nwalal, Issa, Jean-Claude Olivry & Georges Emmanuel Ekodeck

161

Investigations of the sediment budget of a reach of the Yellow River in the Loess Plateau Jueyi Sui, Peter Jackson & Daxian Fang

172

The relationship between suspended and bed load transport in river channels Zygmunt Babiński

182

Bankfull and bed load effective discharge in a steep boulder-bed channel L. Mao, F. Comiti, A. Andreoli, M. A. Lenzi & G. R. Scussel

189

Bed load transport described by a one-dimensional gamma func-tions model Geraldo Wilson Júnior

196

Investigating sediment cascades using field measurements and spatial modelling Michael Becht, Florian Haas, Tobias Heck-mann & Volker Wichmann

206

The effect of rainfall intensity on sediment transport in a scoria-rich river on Miyakejima Island, Japan Yasuhiro Doi, Katsuo Sasa-hara, Takao Yamakoshi & Haruo Nishimoto

214

A new series of sediment collectors for developing bed load sedi-ment budgets and restoring streams David A. Braatz & Randall L. Tucker

222

Hydrological and instrumentation aspects of monitoring and analysing suspended sediment transport crossing international borders G. Schindl, M. Studnicka, A. Eckelhart & W. Summer

227

3 Sediment Storage

A suspended sediment budget for the Liu River basin, China Haoming Fan & Qiangguo Cai

243

Variations spatio-temporelles du bilan sédimentaire dans le bas-sin Amazonien Brésilien, à partir d’un échantillonnage décadaire Alain Laraque, Naziano Filizola & Jean Loup Guyot

250

Storage of fine-grained sediment and associated contaminants within the channels of lowland permeable catchments in the UK Adrian L. Collins, Desmond E. Walling & Graham J. L. Leeks

259

The use of high-resolution field laser scanning for mapping sur-face topography in fluvial systems George Heritage & David Hetherington

269

Daily fine sediment dynamics on an active Alpine glacier out-wash plain David Hetherington, George Heritage & David Milan

278

Sediment deposition in riparian ecosystems evaluated by differ-ent methods Gerd Sparovek, Osny Oliveira Santos Bacchi, Miguel Cooper, Joseline Filippe, Vladia Correchel & Carlos Eduardo Pinto Juhasz

285

Sedimentation rates in the Corumbataí River basin, Brazil, de-rived from 210Pb measurements Daniel Marcos Bonotto, Kelly Yaeko Miyashiro De Almeida & Sammy Sampaio Sieber

294

Sediment accumulation determined with 210Pb geochronology for Strickland River flood plains, Papua New Guinea Rolf Aalto & William Dietrich

303

The role of flood plains in the hydrology and sediment dynamics of the Amazon River, Brazil Laurence Maurice-Bourgoin, Jean-Michel Martinez, Julien Grélaud, Naziano Filizola & Geraldo Resende Boaventura

310

4 Sediment Yield

The sediment budgets of hill reservoirs in small catchments in North Africa and the Middle East Jean Albergel, Jean Collinet, Yannick Pépin, Patrick Zante, Slah Nasri, Mohamed Boufaroua, Abdallah Droubi & Abdelaziz Merzouk

323

Erosion of deposits from the pyroclastic flow that occurred on Mt Merapi, Indonesia in July 1998 Katsuo Sasahara, Masanori Kaneko, Masanobu Takeuchi, Noriyuki Minami & Subarkah

332

Sediment yield scale dependency in the River Eden basin, northwest England James Bathurst, Paul Quinn, Jérémie Gravier, Jenny Orange, Pascal Vivier & Silke Vogel

339

Régime et bilan du flux sédimentaire de l’Amazone à Óbidos (Pará, Brésil) de 1995 à 2003 Jean Loup Guyot, Naziano Filizola & Alain Laraque

347

Suspended sediment fluxes in the large river basins of Brazil Jorge Enoch Furquim Werneck Lima, Walszon Terllizzie Araújo Lopes, Newton de Oliveira Carvalho, Maurrem Ramon Vieira & Euzebio Medrado da Silva

355

Key word index 365

List of the contents of Sediment Budgets 2 (IAHS Publ. 292) 369

Preface

Since the early 1980s, the International Commission on Continental Erosion (ICCE) of the International Association of Hydrological Sciences (IAHS) has organized a large number of highly successful symposia and workshops dealing with various aspects of erosion and sedimentation. These have included: The Symposium on Erosion and Sediment Transport Measurement, Florence, Italy, 1981

(IAHS Publ. 133);The Symposium on Recent Developments in the Explanation and Prediction of Erosion and

Sediment Yield, Exeter, UK, 1982 (IAHS Publ. 137);The Symposium on Dissolved Loads of Rivers and Water Quantity/Quality Relationships,

Hamburg, Germany, 1983 (IAHS Publ. 141);The Symposium on Drainage Basin Sediment Delivery, Albuquerque, New Mexico, USA,

1986 (IAHS Publ. 159);The Workshop on Erosion, Transport and Deposition Processes, Jerusalem, Israel, 1987

(IAHS Publ. 189); The Symposium on Sediment Budgets, Porto Alegre, Brazil, 1988 (IAHS Publ. 174); The Symposium on Sediment and the Environment, Baltimore, USA, 1989 (IAHS

Publ. 184); The Symposium on Erosion, Debris Flows and Environment in Mountain Regions, Chengdu,

China, 1992 (IAHS Publ. 209); The Symposium on Erosion and Sediment Transport Monitoring Programmes in River

Basins, Olso, Norway, 1992 (IAHS Publ. 210);The Symposium on Sediment Problems: Strategies for Monitoring Prediction and Control,

Yokohama, Japan, 1993 (IAHS Publ. 217); The Symposium on Variability in Stream Erosion and Sediment Transport, Canberra,

Australia, 1994 (IAHS Publ. 224); The Symposium on the Effects of Scale on the Interpretation and Management of Sediment

and Water Quality, Boulder, USA, 1995 (IAHS Publ. 226);The Symposium on Erosion and Sediment Yield: Global and Regional Perspectives, Exeter,

UK, 1996 (IAHS Publ. 236); The Symposium on Human Impact on Erosion and Sedimentation, Rabat, Morocco, 1997

(IAHS Publ. 245); The Symposium on Modelling Soil Erosion, Sediment Transport and Closely Related

Hydrological Processes, Vienna, Austria, 1998 (IAHS Publ. 249); The Symposium on the Role of Erosion and Sediment Transfer in Nutrient and Contaminant

Transfer, Waterloo, Canada, 2000 (IAHS Publ. 263); The Workshop on Erosion and Sediment Transport Measurement in Rivers: Technological

and Methodological Advances, Oslo, Norway, 2002 (IAHS Publ. 263); The Symposium on the Structure, Function and Management Implications of Fluvial

Sedimentary Systems, Alice Springs, Australia, 2002 (IAHS Publ. 276);The Symposium on Erosion Prediction in Ungauged Basins: Integrating Methods and

Techniques, Sapporo, Japan, 2003 (IAHS Publ. 279);The Symposium on Sediment Transport through the Fluvial System, Moscow, Russia, 2004

(IAHS Publ. 288)

The Foz do Iguaçu symposium on Sediment Budgets builds on this legacy and focuses on the important topic of sediment budgets. In so doing, it returns to a theme that was first considered almost 17 years ago, also in Brazil, at the Porto Alegre Symposium on

Sediment Budgets (IAHS Publ. 174). It is highly appropriate that Brazil should again be the venue of this second symposium on sediment budgets, both because of the success of the first meeting and because of the many sediment-related problems that are faced by this vast country, with its many large rivers and its wide range of physiographic conditions. Also, with nearly 17 years having elapsed since the original symposium, it is timely to revisit this important topic, which draws together the many different aspects of erosion and sediment mobilization, sediment transport, sediment storage, and sediment yield, by providing an integrated view of the sediment sources, transfers, sinks and outputs of drainage basins, at many different scales. The symposium has been co-sponsored by UNESCO and represents a contribution to the International Sedimentation Initiative (ISI) of the UNESCO International Hydrological Programme (IHP VI).

There have been several key developments in the general area of sediment budget investigations during the years since the Porto Alegre symposium. First, there has been an increasing awareness of the wide-ranging environmental implications of increased sediment loads in rivers and of the need for an improved understanding of catchment sediment budgets as an essential prerequisite for the development of effective sediment management and control strategies. Second, there have been major developments and advances in the techniques and models available for establishing and predicting catchment sediment budgets. The use of environmental radionuclides, such as 137Cs, 210Pb and 7Be, as sediment tracers has, for example, opened up many new opportunities for investigating catchment sediment budgets, particularly in relation to identifying sediment sources, quantifying rates of sediment mobilization, and establishing the importance of sediment sinks. In addition, the continuous recording of surrogate measures of suspended sediment flux (e.g. turbidity) in lieu of manual sampling, with all its attendant problems, has provided an improved understanding of the short-term temporal variability of suspended sediment concentrations and has resulted in more reliable estimates of suspended sediment fluxes. Equally, developments in distributed modelling and the use of remote sensing have been exploited in sediment budget investigations to provide an improved capacity to represent the marked spatial variability in the components of the sediment budgets encountered in many catchments and river basins. Further, the advent of readily available GIS software for desktop computers and associated databases has provided a much more accurate basis for spatial analysis and for providing details on the type of land-use variations that can exercise significant impacts on erosion and sediment yield. Finally, there appears to be a growing recognition of the significance of fine sediment as a carrier of a wide variety of chemical constituents, including trace elements, persistent organic pollutants, and nutrients, and the need to quantify sediment-associated chemical fluxes. Many of these developments are usefully exemplified in the papers of the Foz do Iguaçu Symposium.

The response to the call for papers for the Foz do Iguaçu symposium far exceeded expectations (more than 150 abstracts), and should be viewed as an indication of how significant sediment-related issues are to the environmental and scientific communities. As a result, the symposium was extended over the full duration of the Scientific Assembly (five days). More than 80 papers were selected for oral presentation and inclusion in the pre-published proceedings, and a substantial number of the remaining papers will be presented as posters. It is hoped to publish the poster papers as a CD. For the first time for an ICCE symposium, it has proved necessary to produce two volumes of proceedings

(IAHS Publications 291 and 292); these contain 81 papers. The papers published in the two proceedings volumes cover a wide range of topics,

and draw together information and findings from many different areas of the world, including North and South America, Australia, Europe, Africa and Asia. The inclusion of a significant number of papers with a South American focus represents an important achievement, since this area of the world has been poorly represented in most previous symposia, with the notable exception of the Porto Alegre Symposium held in 1988. The papers have been grouped into eight themes that cover the key components of catchment sediment budgets as well as a number of integrating themes.

Volume 1 of the proceedings focuses on the main components of the sediment budget and includes sections dealing with, firstly, Sediment mobilization and sources, secondly Sediment transport and transfer, thirdly Sediment storage, and, finally, Sediment yields. The papers highlight important advances in our understanding of soil and sediment redistribution in small catchments, the major developments in sediment source tracing that have occurred since 1988, key improvements in monitoring techniques, greatly improved understanding of the role and behaviour of sediment sinks, particularly river flood plains, and the increasing availability of reliable data on sediment yields from different areas of the world and particularly for many of the large rivers of Brazil.

Volume 2 includes four sections containing papers that emphasize the value of sediment budgets in providing an integrating framework, or perspective, for both scientific investigations and for environmental management. The section on Sediment budgets reports the results of studies for catchments in a wide range of environments and emphasizes the increasing availability of information on the nature of such budgets. The next section on Modelling sediment budgets and their components highlights both the wide range of modelling approaches, and the potential for applying existing models within a sediment budget framework. The section on Human impact on sediment budgets emphasizes the potential importance of human activity, especially land-use activities, in modifying both the individual components of the sediment budget and the overall budget, and contains a number of papers dealing with the impact of dams. Finally, the section on Sediment problems and sediment management strategies, whilst containing only a limited number of papers, demonstrates how the sediment budget concept can be integrated into environmental management strategies.

The editors would like to express their gratitude to UNESCO and IAHS for their financial and logistical support for the Symposium and to their Brazilian co-convenors Newton Carvalho and Edmilson Teixera for their valuable help in publicizing and promoting the symposium, screening abstracts, and organizing the symposium programme. The task of reviewing, editing and compiling the two proceedings volumes, containing more than 80 papers, within the space of four months, has proved a major challenge and thanks are extended to all the contributing authors who helped by providing manuscripts in a timely manner and by responding promptly to reviewers’ and editors’ comments and queries, and to the Geography Department of the University of Exeter and the US Geological Survey for their invaluable support. Thanks also are extended to Michel Meybeck (University of Paris VI) for his generous help in editing several of the manuscripts written in French. Equally, special thanks are due to Cate Gardner and Penny Farnell who took the numerous and diverse electronic files containing the papers and their figures and tables, and converted, standardized and formatted them to

produce the final printed volumes, in record time. They also provided valuable guidance and gentle reminders of deadlines and outstanding tasks, which ensured that the editors completed their work by the final deadline.

Des WallingDepartment of Geography, University of Exeter

Amory Building, Rennes Drive, Exeter EX4 4RJ, UK

Art Horowitz US Geological Survey, Peachtree Business Center

3036 Amwiler Road, Atlanta, Georgia 30360, USA

Sediment Budgets 1 (Proceedings of symposium S1 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 291, 2005, 3-10.

The sediment budgets of cultivated slopes and slope catchments: an evaluation of the influence of slope morphology

VALENTIN GOLOSOV & LEONID LITVINLaboratory for Soil Erosion and Fluvial Processes, Faculty of Geography, Moscow State University, GSP-2, Vorob’evy Gory, 119992, Moscow, [email protected]

Abstract Evaluation of the net soil losses from cultivated slopes represents an important requirement for assessing sediment redistribution in river basins. Different methods can be used to determine the spatial pattern of soil loss/deposition within cultivated areas. These include the soil-morphological method, direct measurement of rills and deposition zones and radionuclide techniques. The soil-morphological method provides information on soil losses for the entire period of cultivation. Soil losses for single erosion events can be assessed using direct measurements of rills. The caesium-137 (137Cs) and excess lead-210 (210Pbex) techniques provide information on sediment redistribution over approximately the past 50 and 100 years respectively. Available data concerning net soil losses from slopes of different topographic configurations, obtained using these different methods, were collected from studies undertaken in various landscape zones around the world. The relationship between erosion and deposition was shown to be very similar for slopes or slope catchments of similar configuration, despite differences in the temporal scales, the methods employed and the landscape characteristics (soil, precipitation, etc.). Hence, the morphological characteristics exert a key influence on sediment redistribution on hillslopes. Establishment of buffering capacity coefficients for different slope types permits the sediment output from cultivated areas to be predicted, based on a classification of slope morphology and using information from topographic maps or DEMs.Key words deposition; sediment redistribution; slope form; slope sediment budget; soil erosion

Sediment Budgets 1 (Proceedings of symposium S1 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 291, 2005, 11-20

Human-accelerated soil redistribution within an intensively cultivated dry valley catchment in southern European Russia

VLADIMIR R. BELYAEV, VALENTIN N. GOLOSOV, NADEZHDA N. IVANOVA, MAXIM V. MARKELOV &ELVIRA V. TISHKINALaboratory of Soil Erosion and Fluvial Processes, Faculty of Geography, Moscow State University, GSP-2, Vorob’evy Gory, 119992, Moscow, [email protected]

mailto:[email protected]

Abstract The Stavropol Uplands is an area with some of the most severe soil erosion in European Russia. This poses serious problems in the region and requires quantitative assessment. The study reported used a combination of methods (geomorphological mapping, soil profile comparison, 137Cs tracing and USLE-based modelling) to investigate soil and sediment redistribution during the period of serious human impact within the Maly Kazgulak dry valley catchment (area ~14 km2, main valley length ~10 km). Soil redistribution dynamics were assessed for two different timespans, corresponding to the periods before and after the beginning of 137Cs fallout. By studying three typical slope segments in the upper part of the catchment, the main characteristics of sediment delivery from arable slopes have been established. By combining this information with stratigraphic descriptions and 137Cs data from sediment sections in the valley bottom, a provisional sediment budget has been constructed for the upper part of the study catchment. The general similarity of valley slope morphology within the study catchment provides a basis for extrapolating the data obtained to the entire catchment area.Key words caesium-137; dry valley catchment; human impact; sedimentation; sediment budget; sediment redistribution; soil erosion; southern European Russia; USLE-modelling


Etude du ruissellement et du transport solide dans les Monts de Beni-Chougrane, Algérie: utilisation de la simulation de pluie

MOHAMED MEDDI1, YAHIA BOUKHARI2 & BOUDDKHIL MORSLI3

1 LRERP, Université de Khemis Miliana, Algérie [email protected]

2 Centre Universitaire de Mascara, Algérie3 INRF, Macsara, Algérie

Résumé En Algérie, la généralisation et l’accélération de l’érosion révèlent des aspects de plus en plus inquiétants, voire catastrophiques. Les zones des montagnes restent les plus touchées par ce phénomène. Les monts de Béni-Chougrane représentent un bon exemple du Tell occidental pour l’analyse des problèmes d’érosion. L’étude du ruissellement et du transport solide par la technique de simulation de pluie nous a permis à volonté de fixer les caractéristiques des averses et l’état d’humidité du sol tout en prenant en compte les variables in situ. L’établissement d’un protocole expérimental de simulation de pluie consiste à définir la chronologie des différentes averses avec leurs caractéristiques, de façon à se rapprocher d’une situation naturelle moyenne, en apportant le maximum de renseignements dans un temps relativement court. Les résultats trouvés montrent l’intérêt de la technique dans la compréhension du phénomène.Mots clefs Algérie; érosion; Monts de Beni-Chougrane; ruissellements; simulation de pluie

Use of rainfall simulation to investigate runoff and sediment transport in the Beni-Chougrane Mountains, AlgeriaAbstract In Algeria, both the increasing incidence and the acceleration of erosion must be seen as a cause for serious concern. The mountain zones are most affected by such problems. The Beni-Chougrane Mountains provide a good example of an area of the Western Tell for the study of erosion problems. Use of a rainfall simulator to study runoff and sediment transport affords a means of controlling both rainfall characteristics and soil moisture levels, so that the influence

of other local variables can be explored. Establishment of an experimental protocol for rainfall simulation investigations requires consideration of both the timing and the magnitude of the rainfall inputs, in order to both replicate natural conditions and to obtain the maximum amount of information in a relatively short time. The results obtained confirm the value of the approach in understanding erosion processes.Key words Algeria; Beni-Chougrane mountains; erosion; rainfall simulation; runoff

Sediment Budgets 1 (Proceedings of symposium S1 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 291, 2005.,29-36

Sediment production by landslides in Hong Kong: two case studies

M. R. PEART1, J. P. KING2 & M. E. RUSE3

1 Department of Geography, The University of Hong Kong, Hong [email protected]

2 Geotechnical Engineering Office, Civil Engineering and Development Department, Hong Kong 3 Fugro (Hong Kong) Ltd, Hong Kong

Abstract Landslide studies in Hong Kong are increasingly providing budgets of active debris through the landslide scar and, in some cases, into the stream system. These data are reviewed and two case studies of landslide debris entering the fluvial system are reported. In the first case study, two small landslides of 50 m3 and 7 m3 volume occurred above a stream sediment monit-oring station, in 2001 and 2003 respectively. While almost all of the debris remained on the slope, both events resulted in increased stream sediment transport in the stream. In the second case study, debris from a 1600 m3 landslide formed a delta of approximately 200 m3 upon entering a reservoir. Sediment budgets from the landslides illustrate the role of mass movement in the production of sediment and the coupling of the hillslope and fluvial systems. They provide information on the nature of material delivered to the drainage system and evidence of the selective transport of materials. Possible influences on the controls on sediment production by landslides are also discussed.Key words Hong Kong; landslide; reservoir sedimentation; sediment budget; suspended sediment properties


Post-eruption sediment budget of a small catchment on the Miyakejima volcano, Japan

SATOSHI TAGATA1, TAKAO YAMAKOSHI1, YASUHIRO DOI1, KATSUO SASAHARA1, HARUO NISHIMOTO1 & HIROSHI NAGURA2

1 Public Works Research Institute, Erosion and Sediment Control Research Group, Volcano and Debris Flow Team, 1-6 Minamihara, Tsukuba, Ibaraki 305-8516, Japan [email protected]

2 Mathematical Assist Design Lab, 1066 Yoshizawamachi, Ota, Gunma 373-0019, Japan


Abstract The Miyakejima volcano erupted in 2000, emitting a massive quantity of fine tephra. The deposition of the tephra encouraged erosion processes. Gullies rapidly developed in the upper slope close to the peak, including the slope of interest in this study. To understand post-eruption erosion processes, an aerial photograph survey and airborne laser scanning survey were conducted. The complementary analysis of the survey data revealed the following: (a) The total volume of the eroded sediment exceeds that of the tephra deposited by the 2000 eruption. The amount eroded in the four years since the eruption was estimated at 470 000 m3 while the deposition of tephra is estimated at about 370 000 m3. (b) Gully erosion was the dominant process on the study slope. It accounted for at least 87% of the total erosion, while rill and sheet erosion represented 5 and 8%, respectively. (c) Gully erosion almost stopped several months after the eruption. (d) The gullies eroded to considerable depths through the new tephra mantle. Almost 80% of the gully-eroded sediment was original soil. (e) The post-eruption erosion rate observed on the upper slope of the Miyakejima volcano was almost the largest of the rates reported in previous studies. This occurs not only because the mountain of the Miyakejima volcano consists of erodible sediment, but also because few studies have documented the erosion rate of the uppermost slope of a volcano in the very early stages of erosion.Key words erosion rate; gully erosion; laser scanning survey; Miyakejima volcano, Japan


The organic carbon dynamics of a small catchment in the humid tropics

J. R. NDAM-NGOUPAYOU1, J. L. BOEGLIN2, J. L. PROBST2,3,J. J. BRAUN4, M. MEYBECK5 & G. NKOUE NDONDO1

1 Dept of Earth Sciences, Faculty of Sciences, PO Box 812, University Yaoundé I, [email protected] or [email protected]

2 LMTG, UMR 5563, 14 Av. Edouard Belin, F-31400 Toulouse, France3 ENSAT, BP 107, Auzeville Tolosane, F-31326 Castanet Tolosan, France4 IISc, Indo-French Cell for Water Sciences, Dept of Metallurgy, Bangalore 560012, India5 Sisyphe, UPMC, case 123, T26-5étage, 4 Place Jussieu, F-75252 Paris Cedex 05, France

Abstract The general purpose of this study is to understand the dynamics of organic carbon in a humid tropical environment by investigating the transfer of dissolved and particulate organic carbon (DOC, POC), and total mineral dissolved solids (TDS) and total suspended solids (TSS), in the different functional pools of the Nsimi catchment at Zoetele in south Cameroon (Central Africa). The carbon stock reaches 59 000 t km-2 in the soil cover (mean thickness about 30 m), and demonstrates marked enrichment in the upper 2 m of the profile. The DOC content in the wet atmospheric deposits is negligible, but recycling by throughfall is significant (5.45 t km -2

year-1). DOC is very abundant in the coloured (“tea water”) drainage waters that have flowed through the wet depressions (concentrations near 16 mg l-1 and fluxes between 5 and 8 t km-2 year-1) and is of the same magnitude as the TDS. The organic matter plays a key role in the dissolution and transport of cations and trace elements, as well as in compensating for the anionic deficit observed in these waters. The POC fluxes (0.6–1.4 t km-2 year-1) represent about 20% of the TSS. Based on the total carbon outputs documented by the study, the turnover time of this element in the soils can be estimated to be about 950 years in the upper part of the soil cover. Key words atmospheric deposition; Cameroon; Central Africa; humid tropics; hydrobiogeochemistry; organic carbon; soil cover; stream water; weathering rate



Contributions of authigenic iron compounds to fluvial suspended sediment concentrations and fluxes in the Nete sub-basin, Belgium

ELIN VANLIERDE1, JAN DE SCHUTTER2, JORIS F. A. MEYS3, FRANK MOSTAERT2 & PATRIC JACOBS1

1 Department of Geology and Soil Science, Research unit for Sedimentology and Engineering Geology, University of Ghent, Krijgslaan 281 S8, B-9000 Ghent, [email protected]

2 Flanders Hydraulics Research, Ministry of the Flemish Community, Berchemlei 115, B-2140 Borgerhout (Antwerp), Belgium

3 Laboratory for Ecophysiology, Biochemistry, and Toxicology, University of Antwerp – UA, Groenenborgerlaam 171, B2020 Antwerp, Belgium

Abstract In the Nete Basin (Flanders, Belgium), there are indications that the chemical precipitates derived from groundwater-associated Fe(II) seeping into the overlying surface water significantly contribute to the composition, concentration, and fluxes of suspended sediment. For purposes of evaluation, model-derived concentrations were compared with those determined from actual samples. Missing suspended sediment concentrations were estimated from a site-specific rating curve (a stepwise linear regression model) generated from log-transformed data for suspended sediment concentration, gauge height, baseflow, and interflow). Based on various estimates of the concentration of Fe(II) in groundwater, as well as several other factors, authigenic iron compounds may constitute from 36 to 97% of the sediment load in the basin. However, the best current estimate, based on a rating curve model relating groundwater flow to authigenic mineral formation is 70%. Key words authigenic iron compounds; Belgium; suspended sediment concentration; suspended sediment flux


A comparison of erosion rates obtained using the 137Cs technique and direct measurements on runoff plots

VLADIA CORRECHEL1, OSNY OLIVEIRA SANTOS BACCHI1, ISABELLA CLERICI DE MARIA2,SONIA CARMELLA FALCI DECHEN2 & KLAUS REICHARD1

1 Centre for Nuclear Energy in Agriculture, University of São Paulo, CP 96, CEP 13.400-970 Piracicaba, SP, [email protected]

2 Campinas Agricultural Institute (IAC), CEP 13.020-902 Campinas, SP, Brazil

Abstract Measured 137Cs losses (Bq m-2) from long-term runoff plots under tropical conditions and corresponding estimated soil erosion rates (Mg ha -1 year-1) were significantly correlated with directly measured soil losses from the same plots, during the same period (1963–2002). A tendency for higher 137Cs inventories to be found in soil profiles from the bottom third of the slopes could be explained by the restricting effect of the collector system on the outflow runoff or

by tillage translocation. Despite the very low 137Cs activity found, and the small number of plots analysed, the 137Cs technique yielded consistent results, closely comparable with those obtained by the traditional direct measurements on long-term runoff plots.Key words caesium-137; fallout; radioisotopes; radionuclide; sediment loss; soil erosion

Sediment Budgets 1 (Proceedings of symposium S1 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 291, 2005., 70-77

The pattern of soil redistribution along a transect in the central Ebro basin (NE Spain) and its controls

ANA NAVAS1, DESMOND E. WALLING2, TIMOTHY A. QUINE2, JAVIER MACHIN1 & JESUS SOTO3

1 Estación Experimental de Aula Dei, CSIC Apartado 202, ES-50080 Zaragoza, Spain [email protected]

2 Department of Geography, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK

3 Departamento de Ciencias Médicas y Quirúrgicas, Universidad de Cantabria, Avenida Cardenal Herrera Oria s/n, ES-39011 Santander, Spain

Abstract The central part of the Ebro basin is threatened by desertification under the scenario of climate change for Mediterranean areas. A survey to examine the pattern of soil erosion and sedimentation was carried out along a climatic and altitudinal transect extending from the centre of the basin to the northern divide in the Pyrenees. Soil redistribution rates were assessed by using fallout 137Cs measurements on representative areas that are presented as case studies. The central steppe is the most severely affected by erosion, as indicated by highly depleted 137Cs levels. In the semiarid area, erosion mainly affects the slopes that are sparsely vegetated and the cultivated valley floors. In the Pyrenees, soils on steep slopes are quite stable under dense shrub or forest cover. On the sparsely vegetated slopes of abandoned fields, erosion is severe, particularly on south facing slopes. These case studies emphasize both the spatial contrasts in soil redistribution rates that can be found in Mediterranean areas and the intense erosion and sedimentation dynamics that can threaten the sustainability of soil and water resources.Key words caesium-137; Ebro basin; erosion; controlling factors; sedimentation; Mediterranean environments; Spain


Interpreting 137Cs depth profiles with no single peak in lake deposits in China

XINBAO ZHANG1,2, XIUBIN HE1 & YONGQING QI1 1 Chengdu Institute of Mountain Hazards and Environment, CAS, Chengdu 610041, China

[email protected] State Key Laboratory of Loess and Quaternary Geology, Earth Environment Institute, CAS, China

Abstract 137Cs depth profiles lacking the characteristic peak associated with the period of peak fallout in the early 1960s are reported for a number of lakes in China and reasons for their unusual profile shapes are presented. Uniform 137Cs depth profiles are found in the deposits of most glacial lakes, because the annual 137Cs inputs since 1963 to the lakes from the glaciers in the catchments via melt runoff are controlled primarily by the velocities of the glaciers, which have changed little over recent decades. Uniform 137Cs depth profiles are also frequently found in shallow lakes, because the sediment deposits on the lake bottom are prone to human disturbance. The so-called 1974 and 1986 137Cs peaks found in the profiles from two lakes in Yunnan Province are not true 137Cs peaks, but represent “mirror image peaks” caused by the low 137Cs concentrations associated with sediment deposited in years with low erosive precipitation immediately prior to 1974 and 1986.Key words caesium-137; China; depth distribution; lake deposits


Riverbank erosion and its importance to uncertainties in large-scale sediment budgets

RONALD DE ROSE1, DAVID J. WILSON2, REBECCA BARTLEY1 & SCOTT WILKINSON1

1 CSIRO Land and Water, GPO Box 1666, Canberra, ACT 2601, [email protected]

2 CRC for Catchment Hydrology, SAGES, The University of Melbourne, Victoria 3010, Australia

Abstract In previous studies sediment budgets have been modelled at national and regional scales across many areas of Australia. Of the three dominant erosion processes considered (gully, hillslope and riverbank), riverbank erosion has been identified as having large systematic errors. In this paper we determine riverbank erosion rates by relating the average rate of meander migration to catchment or river attributes (e.g. discharge, riparian vegetation), and show that these typically only explain a small amount (<50%) of the variability in observed erosion rates. We demonstrate a methodology for deriving rates of riverbank erosion for 25 sites in southeastern Australia from historical river plan surveys, and present preliminary results from these surveys which support previous findings that the rates of meander migration and bank erosion for many Australian rivers are low by global standards. The paper also presents progress towards the development of an improved empirical model of riverbank erosion.Key words meander migration; riverbank erosion; sediment budget; SedNet; spatial models


Identification of sediment sources in a small grazed Sahelian catchment, Burkina Faso

HAROUNA KARAMBIRI1 & OLIVIER RIBOLZI2


1 Ecole Inter-Etats d’Ingénieurs de l’Equipement Rural (EIER), 03 BP 7023 Ouagadougou 03, Burkina Faso [email protected]

2 UR ECU 049, Institut de Recherche pour le Développement (IRD), IFR Environnement et Gestion de l’Espace Régional, Bâtiment EGER, Aile C, F-78850 Thivernal Grignon, France

Abstract The Sahelian region of Burkina Faso is currently facing serious problems of natural resource degradation, especially soil erosion, due to the aggressive climate and anthropogenic impacts. This study aimed to quantify total soil losses at the outlet of a catchment and to estimate the contribution of different sediment sources. To do this, surface water flow and associated particulate material transport were monitored for three years (1998–2000) in a small grazed catchment (1.4 ha). About 64% of the catchment is covered by permeable sandy aeolian deposits (DRY soil surface type), which support most of the vegetation, and about 34% is covered by impermeable bare soils (ERO soil surface type). To establish the contribution of the two surface soil types to the sediment load observed at the catchment outlet, several different techniques were used. These included the particle-size distribution of the sediment, clay mineralogy (kaolinite/quartz ratio) and physically-based modelling. The results indicated that the ERO surface type appeared to be the main source of sediment within the catchment. Key words Burkina Faso; Sahel; sediment sources; soil loss; water erosion


Using environmental radionuclides to elucidate sediment sources within a small drainage basin in the Polish Flysch Carpathians

WOJCIECH FROEHLICH1 & DES E. WALLING2

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

2 Department of Geography, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK

Abstract The work reported in this contribution was undertaken in the Homerka instrumented catchment in the Polish Flysch Carpathians, where a combination of conventional methods of documenting sediment mobilization, transfer and deposition and sediment tracing techniques have been used over the past 30 years to investigate the sediment budget of the catchment. This contribution focuses on the use of environmental radionuclides, and more particularly 137Cs, to trace the main sources of the suspended sediment exported from the study catchment. Unmetalled roads were identified as the main suspended sediment source, with the channels and active gullys also providing significant contributions. The findings of the source tracing investigations are consistent with the results of other conventional monitoring undertaken in the study catchment aimed at identifying the main suspended sediment sources.Key words Carpathians; caesium-137; environmental radionuclides; Homerka catchment, Poland; sediment budget; suspended sediment sources; source tracing; unmetalled roads



Investigating sediment sources within a small catchment in southern Italy

PAOLO PORTO1,2, DES E. WALLING1 & GIOVANNI CALLEGARI3

1 Department of Geography, University of Exeter, Amory Building, Rennes Drive,Exeter EX4 4RJ, UK [email protected]

2 Dipartimento di Scienze e Tecnologie Agro-Forestali e Ambientali, Università degli Studi “Mediterranea” di Reggio Calabria, Italy

3 CNR – Istituto per i Sistemi Agrari e Forestali per il Mediterraneo, Sezione Ecologia e Idrologia Forestale, Rende (Cs), Italy

Abstract Soil erosion is a serious problem in many areas of Italy, particularly in the south, where rates of soil loss can exceed 100–150 t ha-1 year-1. Although the impact of these high rates of soil loss has traditionally been assessed in terms of soil degradation, off-site problems related to more general environmental degradation are attracting increasing attention. In order to implement meaningful sediment control strategies, it is necessary to establish both the nature and the location of the main sediment sources within a catchment. Sediment fingerprinting has been increasingly identified as an effective approach for assembling information on suspended sediment sources. The study reported uses source fingerprinting techniques, based primarily on radiometric fingerprints (137Cs and unsupported 210Pb) to establish the primary sediment sources within a small forested catchment (1.38 ha) located in Calabria, southern Italy, where independent information on the spatial pattern of surface erosion rates was available from 137Cs measurements. The source tracing investigation showed that most sediment originates from the south- facing slopes, where the tree cover is discontinuous, emphasizing the importance of vegetation cover in influencing sediment mobilization from the study area. These findings are consistent with the previous work involving 137Cs measurements, which again identified the south-facing slopes with discontinuous tree cover as the areas with the highest rates of soil loss.Key words caesium-137; erosion rates; lead-210; sediment tracing; soil erosion; source fingerprinting; southern Italy; suspended sediment


Suspended sediment sources in British rivers

D. E. WALLING & A. L. COLLINSDepartment of Geography, University of Exeter, Amory Building, Rennes Drive,Exeter EX4 4RJ, [email protected]

Abstract Sedimentation problems have traditionally been viewed as being of limited importance in Britain. As a result there is no national sediment monitoring programme and relatively little is known about the suspended sediment loads of British rivers. The recent growth of awareness of the wider environmental significance of fine sediment and its important role in the sediment-associated transfer of nutrients and contaminants and in degrading aquatic ecosystems has emphasized the need for sediment control and management programmes. The design of such programmes requires an improved knowledge and understanding of the suspended sediment

budgets of British catchments. In addition to information on sediment loads and sediment yields, there is a need for information on sediment source. Such information is difficult to obtain using traditional techniques, but source fingerprinting procedures offer an effective and reliable means of assembling such data. The authors and their co-workers have undertaken a number of source tracing investigations in British catchments and the findings from 48 catchments are synthesized in this contribution. The results are reviewed and their implications for the sediment budgets of British catchments and for the design and implementation of effective sediment management programmes are discussed. Key words British rivers; sediment sources; source fingerprinting; source tracing; suspended sediment


Fluvial contribution to the sediment budget of the Tay Estuary, Scotland, assessed using mineral magnetic fingerprinting

PIERRE A. JENKINS, ROBERT W. DUCK & JOHN S. ROWANEnvironmental Systems Research Group, Department of Geography, University of Dundee, Dundee DD1 4HN, [email protected]

Abstract The sediment budget of the Tay Estuary, Scotland, UK, was evaluated using mineral magnetic fingerprinting. A multivariate unmixing model, based on constrained linear programming, permitted quantification of source contributions to the estuarine bottom sediments. Factor and multivariate discriminant analysis demonstrated that the two fluvial sources could be separated on the basis of five, linearly additive magnetic properties. However, lack of data dimensionality necessitated amalgamation of the two marine sources originally recognized. The model demonstrates the present-day dominance of marine bottom sediment derivation (78 10%), whereas fluvial source contributions are 4 10% from the River Earn and 18 10% from the River Tay. The fluvial contribution should be considered in the context of the Tay being Britain’s foremost river in terms of discharge (long-term average 167 m3 s-1). Source contributions to intertidal flat sediments collected over a spring–neap tidal cycle imply a temporal constancy to bed sediment provenance.Key words bed sediment; fluvial contribution; magnetic fingerprinting; Scotland;sediment budget; Tay Estuary


Impacts of wildfire on effective sediment particle size: implications for post-fire sediment budgets

WILLIAM H. BLAKE1, IAN G. DROPPO2, PETER J. WALLBRINK3, STEFAN H. DOERR4, RICHARD A. SHAKESBY4 & GEOFFREY S. HUMPHREYS5

1 School of Geography, University of Plymouth, Plymouth PL4 8AA, UK

[email protected] 2 National Water Research Institute, Environment Canada, PO Box 5050, Burlington,

Ontario L7R 4A6, Canada 3 CSIRO Land & Water, PO Box 1666, ACT 2601, Australia 4 Department of Geography, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK 5 Department of Physical Geography, Macquarie University, North Ryde, Sydney,

New South Wales 2109, Australia

Abstract Recent work in an Australian catchment has shown that severe wildfires followed by rainstorm events lead to redistribution of topsoil and export of sediment to the local river network. Considering the affinity of nutrients and other contaminants for fine sediment, and the potential for considerable downstream impacts, a sound understanding of the fine-sediment delivery from burnt systems is required. However, past work has shown that fire can modify the particle size distribution of the soil through formation of robust sand-sized aggregates comprising fine clays and silts. Image analysis confirmed the presence of fire-modified soil aggregates in our study area. Analysis of aggregate form and fluvial behaviour showed that fire-modified aggregates are fused, dense and inorganic in nature with settling velocities of an order of magnitude faster than unburnt soil aggregates or classic riverine flocs. This implies an increased potential for storage of nutrient-rich fine sediment within slope units, flood plains and river channels. The unusual behaviour of these composite particles should be considered in the construction of post-fire fine-sediment budgets.Key words aggregate; Australia; fine sediment; fire; nutrients; sediment storage


Estimation of the concentration of suspended solids in rivers from turbidity measurement: error assessment

EDMILSON COSTA TEIXEIRA & PAULO CEZAR CALIARIGrupo de Estudos e Ações em Recursos Hídricos – GEARH/UFES, GEARH/DEA/UFES, CP 01-9011, 29060-970 Vitória, ES, [email protected]

Abstract The concentration of suspended solids in rivers is traditionally determined by means of slow and relatively expensive methods. There is therefore a need for alternative approaches. The development and validation of models which relate the concentration of suspended solids (SSC) to the water turbidity (Turbidity), represents one potential approach. This paper presents the results of a study of the errors involved in the use of SSC/Turbidity models to estimate SSC. Three types of model were developed: in the first, SSC = f(Turbidity); in the second SSC = f(Turbidity, Colour, D50); and in the third SSC = f(Turbidity, Colour, D50, Cu), where Colour is the apparent water colour, and D50 and Cu are the mean diameter and the coefficient of uniformity of the suspended sediment, respectively. For the model SSC = f(Turbidity), the maximum error was 28%, whereas for the model SSC = f(Turbidity, Colour, D50), the maximum error was 23.3%. The simple model SSC = f(Turbidity) was found to have considerable potential, if the model for a given catchment could involve different relationships for different ranges of SSC. In this study, when the SSC range was split into two ranges i.e. 20–320 mg l -1 and 320–640 mg l-1, the maximum errors for the model SSC = f(Turbidity) were equal to 11 and 9%, respectively. The parameters Colour, D50 and SSC were shown to exert a significant effect on the SSC/turbidity relationship. Key words colour; concentration/turbidity relationships; grain size;

suspended sediment concentration; turbidity

Sediment Budgets 1 (Proceedings of symposium S1 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 291, 2005,161-171

Transport des matières en suspension au Cameroun dans un contexte hydroclimatique déficitaire

GASTON LIENOU1, GIL MAHE2, ERIC SERVAT2, RODRIGUE TEGOFACK3, JOSEPH SAHAGU3, JACOB NWALAL3, ISSA3, JEAN-CLAUDE OLIVRY2 & GEORGES EMMANUEL EKODECK1

1 Université de Yaoundé I, Département des Sciences de la Terre, c/o IRD BP 1857 Yaoundé, [email protected]

2 IRD, UMR HydroSciences Montpellier, BP 64 501, F-34394 Montpellier Cedex 5, France3 Centre de Recherches Hydrologiques, BP 4110 Yaoundé, Cameroun

Résumé On étudie les transports des matières, essentiellement en suspension, dans les fleuves et rivières du Cameroun. Un grand nombre de bassins versants, représentant les principales unités climatiques du pays, est suivi simultanément, avec des fréquences de prélèvements adaptées aux divers régimes hydrologiques. Cette étude vise à préciser les variations spatiales des processus de transport, mais surtout, à analyser l’évolution du transport des matières en suspension dans le contexte des changements climatiques et environnementaux (liés ou non aux activités humaines). Les mesures actuelles portent sur six rivières, drainant des bassins versants de superficie variant entre 1500 et 18 000 km2. Dans ce premier article, la méthodologie utilisée d’une part pour l’estimation de la concentration moyenne dans la section et, d’autre part, pour le calcul de la masse totale exportée à l’exutoire des bassins versants est présentée. On s’appuie d’abord sur des tests de représentativité spatiale pour estimer les erreurs qui peuvent être commises en faisant varier le nombre de verticales le long de la section. Ensuite, on effectue des tests de représentativité temporelle pour estimer les erreurs commises en faisant varier d’une part la fréquence des prélèvements et d’autre part la méthode de calcul des flux sur une période. Les différences excèdent 50% en hautes eaux et 25% en basses eaux quand on passe d’un jaugeage de cinq à trois verticales. Pour les bilans des flux, les résultats de trois méthodes de calcul sont sensiblement identiques. En revanche, les écarts atteignent 20% quand la fréquence de prélèvement baisse de moitié, parfois plus de 30% en zone tropicale.Mots clefs Cameroun; changement climatique; hydrologie; transport de matières

Suspended sediment transport in Cameroun in the context of a climatic water deficitAbstract This contribution is concerned with the transport of sediment, primarily in suspension, by streams and rivers in Cameroun. A large number of drainage basins, representing the main climatic units of the country have been investigated simultaneously, with the frequency of sampling adapted to the range of hydrological regimes. These investigations aim to document the spatial variation of sediment transport and, more particularly, the impact of climatic and environ-mental change, both related and unrelated to human impact, on suspended sediment loads. The results presented here relate to six rivers with catchment areas ranging from 1500 to 18 000 km 2. In this initial study, the procedures used to calculate, firstly, the mean concentration in the cross section and, secondly, the sediment load at the basin outlet are considered. Attention is first directed to testing the spatial representativeness of measurements of sediment concentration in the cross section, by considering the errors generated by varying the number of sampling verticals. Subsequently, temporal representativeness is considered by evaluating the errors introduced by varying the sampling frequency and the method employed for flux calculation. In the first case,

errors of greater than 50% during high flows and 25% during lower flows are associated with a reduction in the number of sampling verticals from five to three. In the second case, the three methods employed for calculating the sediment flux are shown to produce very similar results. However, a reduction in sampling frequency by one half can introduce an error of 20%, and this can increase to 30% in the tropical zone.Key words Cameroon; climatic change; hydrology; sediment transport


Investigations of the sediment budget of a reach of the Yellow River in the Loess Plateau

JUEYI SUI1, PETER JACKSON1 & DAXIAN FANG2

1 Environmental Science & Engineering, University of Northern British Columbia, Prince George, British Columbia V2N 4Z9, Canada [email protected]

2 Civil Engineering, Hefei University of Technology, Hefei Anhui 230009, China

Abstract Using sediment concentration (CS) and discharge (Q) data measured at three gauging stations along the reach of the Yellow River in the Loess Plateau, this article focuses on high CS

levels during flood periods and low CS levels under ice covered conditions. The results show that the annual maximum CS is usually less than 30 kg m-3 during the flood season at the upstream Toudaoguai gauging station (TDGS). However, both maximum CS and Q vary dramatically at the downstream Fugu gauging station (FGGS). The value of CS under ice cover is very low compared to CS during flood periods. For the same cumulative percentage undersize, the median grain size of the suspended load under ice cover is much coarser than that under open flow conditions, although Q during the period of ice cover is much less than that under open flow conditions. About 35% of the sediment eroded in the sub-watershed between TDGS and FGGS was produced from the HuangPuChuan watershed, which accounts for only 10% of its drainage area. Key words flood seasons; HuangPuChuan sub-watershed; ice covered period; loess plateau; runoff depth; sediment concentration; Yellow River


The relationship between suspended and bed load transport in river channels

ZYGMUNT BABIŃSKIInstitute of Geography, Bydgoszcz University, ul. Mińska 15, 85-428 Bydgoszcz, [email protected]

Abstract According to the existing literature, the clastic load of the rivers of the world is about four times larger than the dissolved load. Similarly, the suspended load is several times greater than the bed load transport. Values commonly fall within the bounds 85–99% suspended load to 1–15% bed load. The precise proportion depends on the transport power of the river, the hydro-

logical regime, the geological structure of the catchment and human activity. However, the availability of new methods of measurement makes it possible to verify existing data concerning both forms of clastic load. This contribution aims to explore further the relationship between suspended load and bed load transport, to highlight the great divergence evident in the proportions of the total load accounted for by the two load components, and to explain the source of this divergence. The study is based on available literature documenting fluvial transport and incorporates the results of measurements undertaken in the lower Vistula River in Poland.Key words bed load; dissolved load; fluvial transport, sediment budget; suspended load; Vistula River


Bankfull and bed load effective discharge in a steep boulder-bed channel

L. MAO1, F. COMITI1, A. ANDREOLI1, M. A. LENZI1 &G. R. SCUSSEL2

1 Department of Land and Agroforest Environments, University of Padova, Agripolis,Viale dell’Università 16, I-35020 Legnaro (PD), Italy [email protected]

2 Arpav – Avalanche Center of Arabba, Veneto Region, via Passo Campolongo 122, I-32020 Arabba (BL), Italy

Abstract In order to achieve a better understanding of the physical processes involved in incipient bed load transport and channel-forming conditions in high-gradient streams, bed load rate and flow discharge data provided by the Rio Cordon measuring station were analysed. From 1987 to 2003, 22 floods characterized by bed load transport were recorded at the measuring station. From field surveys, the bankfull discharge was estimated to be 2.3 m3 s-1, with a return period of 1.6 years (lognormal distribution). This is consistent with previous findings regarding the frequency of bankfull conditions. Based on the flow duration curve, bankfull stage is exceeded nine hours per year. The effective discharge for bed load transport, i.e. the flow transporting the greatest amount of bed load over a long period, was estimated to be 2.45–2.65 m3 s-1, which is close to the estimated bankfull discharge. Uncertainties associated with establishing the effective discharge are identified and discussed.Key words Alps; bankfull discharge; bed load transport; duration curve; effective discharge; experimental basin; high-gradient streams


Bed load transport described by a one-dimensional gamma functions model

GERALDO WILSON JÚNIORPrograma de Engenharia Oceânica da Universidade do Rio de Janeiro-PENO/COPPE/UFRJ, Centro de Tecnologia, Bloco C, Sala 209, Ilha do Fundão, 21.945-970 Rio de Janeiro, Brazil


[email protected]

Abstract Experiments were performed in open channel flows to evaluate one-dimensional stochastic models for sand transport and dispersion. One series was based on the observation of kinematic characteristics of single grains labelled with 192Ir, in a 30-m long, 0.40-m wide channel subjected to liquid discharges of 12 to 33 l s-1. It was shown that the grain rest periods as well as the step lengths could be described by gamma probability density functions. A one-dimensional Gamma Functions Model (1D-GM) was therefore proposed to describe the longitudinal distances travelled by a group of particles as a function of time. The model was fitted to the results of a second series of experiments with grains labelled with 198Au or simulated by crushed glass containing 192Ir. This paper describes those experiments, the 1D-GM properties and its performance in describing Lagrangean behaviour of groups of particles in the laboratory and in natural watercourses.Key words bed load transport; gamma function; model; rivers; sand transport


Investigating sediment cascades using field measurements and spatial modelling

MICHAEL BECHT, FLORIAN HAAS, TOBIAS HECKMANN & VOLKER WICHMANNChair of Physical Geography, Catholic University of Eichstätt/Ingolstadt, Ostenstrasse 18, D-85072 Eichstätt, [email protected]

Abstract Many geomorphic processes contribute to the sediment budgets of high-mountain geosystems. The interaction of these processes to form a sediment cascade can be investigated, interpreted and visualized on the basis of spatial models calibrated by field measurements. We present the results of field measurements and modelling for a talus slope in one of the two study areas of a large interdisciplinary research project (SEDiment cascades in Alpine Geosystems—SEDAG). The sediment yield of a debris flow event (~12 000 t) is compared with the mean annual sediment yields of rockfall and fluvial processes on the talus cone. In addition, modelling and zonation of the potential process domains for rockfalls and debris flows clearly illustrate the concept of a sediment cascade. Results show that the sediment volume, reworked and removed from the cascade by debris flows, exceeds by far the sediment input by rockfall, so that the sediment volume stored on the talus cone is presently decreasing.Key words debris flow; fluvial erosion; Germany; Northern Limestone Alps; rockfall; sediment budget; sediment cascades; spatial modelling


The effect of rainfall intensity on sediment transport in a scoria-rich river on Miyakejima Island, Japan


YASUHIRO DOI, KATSUO SASAHARA, TAKAO YAMAKOSHI & HARUO NISHIMOTOVolcano and Debris Flow Team, Erosion and Sediment Control Research Group, Public Works Research Institute, 1-6 Minamihara, Tsukuba-shi, Ibaraki 305-8516, [email protected]

Abstract The volcanic eruptions on Miyakejima Island in 2000 triggered serious mudflows in most basins. Since then, the magnitude of sediment transport has decreased over time, as it has after other volcanic eruptions. However, some rivers on the island still discharge considerable volumes of sediment. In order to study the sediment transport dynamics, the authors installed a surveillance camera and a raingauge in the Tatsunesawa River, a typical river where high sediment transport persists. A comparison of the occurrence of sediment transport at the exit of the river basin with total rainfall and rainfall intensity revealed that sediment transport was primarily controlled by rainfall intensity rather than rainfall amount and occurred when the rainfall intensity exceeded a maximum 10-min rainfall of 4–5 mm. On 16 July 2002, despite the comparatively low total rainfall of 13 mm, the maximum 10-min rainfall was 5 mm and sediment transport occurred at the basin outlet. The transported sediment is composed primarily of scoria, comprising porous cinder-like fragments of dark lava with a mean diameter of 12 mm and a coefficient of permeability of 1.25 cm s-1. Low rainfall intensities are easily absorbed by the scoria layer on the river bed and surface runoff only occurs under high rainfall intensities when inflow exceeds outflow. The volume of scoria deposited on the river bed and its permeability exert an important influence on sediment transport. Key words Miyakejima Island, Japan; permeability; rainfall; rainfall intensity; scoria; sediment transport; total rainfall


A new series of sediment collectors for developing bed load sediment budgets and restoring streams

DAVID A. BRAATZ1 & RANDALL L. TUCKER2

1 Streamside Systems LLC, PO Box 245, Boonville, North Carolina 27011, USA [email protected] 2 Streamside Systems LLC, 7440 Liberty Twp. Rd 95, Findlay, Ohio 45840, USA

Abstract Streamside Systems offers a variety of bed load monitoring collectors to sample targeted sizes of bed load sediment for developing watershed sediment budgets, and to remove sediment to restore streams. Prototypes of portable units have been tested for continuous operation (3- to 5-month periods) for sand to medium gravel moving as bed load. The Streamside collectors sample true bed load, and avoid the collection of suspended sediment and organic matter. In low-gradient streams, the Streamside collectors are pumped out and can easily be backflushed or “zeroed” with no safety hazard (i.e. no need to enter a flooded stream). In higher-gradient streams, a siphon removal system will work continuously with a localized drop adequate to flush the sediments (e.g. 1.5 l s-1 through a 600 mm wide collector, using a 50 mm hose). The outlet hose allows samples to be collected safely from the bank, even under high flow conditions and for any desired sample period (seconds to months). The collectors can continue to operate unattended and can stockpile bed load material for later sieve analyses. For medium and large gravel, cobble and even boulders,


much larger Streamside Systems’ bed load collectors utilize removable hopper assemblies downstream from the pumpout or siphon hopper for fines. This is a clear design advantage over pit traps for large material, in that fine sediments are removed on a continuous basis and will not fill the collector basin(s) intended for coarser material. In contrast to small (76 or 152 mm wide) bed load samplers used for short-duration samples, Streamside Systems’ bed load samplers can virtually eliminate subsample variability by targeting total bed load over extended periods.Key words acid mine drainage; bed load; fluvial sediment; habitat restoration; measuring equipment; monitoring; sediment budgets; sediment impacts; total maximum daily load (TMDL)


Hydrological and instrumentation aspects of monitoring and analysing suspended sediment transport crossing international borders

G. SCHINDL, M. STUDNICKA, A. ECKELHART & W. SUMMERFH-Campus Vienna, Civil Engineering-Management, Daumegasse 1/2, A-1100 Vienna, [email protected]

Abstract The transport of suspended sediment in rivers and streams is a natural process increasingly influenced by human activities. It has ecological as well as economic impacts. In order to recognise and react to these changes in river basins, it is important to record the quantities of suspended sediment in a technically correct as well as directly comparable way. The monitoring often has to be undertaken on transboundary river systems. Technical discrepancies in the monitoring strategies as well as institutional, organizational and legal difficulties are a major problem in the adoption of common standardized procedures. This paper summarises the outcome of an International Commission on Continental Erosion (ICCE) Task Force activity aimed at providing general Guidance on standardization and comparison of methods used for the evaluation of sediment transport crossing international borders, focusing on hydraulic aspects as well as on monitoring techniques.Key Words hydraulics; international; monitoring; suspended sediment; transboundary


A suspended sediment budget for the Liu River basin, China

HAOMING FAN1,2 & QIANGGUO CAI1

1 Institute of Geographical Sciences & Natural Resources Research, CAS, Beijing, Building 917, Datun Road, Anwai 100101, China [email protected]

2 Department of Water Conservancy, Shenyang Agricultural University, Shenyang 110161, China

Abstract A mass budget for the suspended sediment load of the Liu River was established for a period of 36 years (1968–2003). The approach was based on analysing the amount of sediment

contributed by the different tributaries and the sediment storage in different reaches, using data available for six gauging stations on the Liu River. The findings indicate that nearly 50% of the suspended sediment flux from upstream tributaries was stored on the downstream riverbed, with almost 75% of this storage occurring in the reach extending from the Nao Dehai Station to the Zhang Wu Station. About 50% of the suspended sediment coming from upstream reached the catchment outlet. The key controls on the sediment budget of the river basin have been investi -gated. The findings reported in this paper have important implications for understanding suspended sediment dynamics and sediment control in river basins.Key words controls; Liu River basin, China; sediment budget; sediment delivery system


Variations spatio-temporelles du bilan sédimentaire dans le bassin Amazonien Brésilien, à partir d’un échantillonnage décadaire

ALAIN LARAQUE1, NAZIANO FILIZOLA2 &JEAN LOUP GUYOT3

1 IRD-LMTG, OBHI, BP 64 501, F-34394 Montpellier Cedex 5, France [email protected]

2 ANA, SPO area hh5, cuadra 3, A05, Qd. 03, CEP 70610-200, Brasília DF, Brésil3 IRD-LMTG, Casilla 18-1209, Lima 18, Pérou

Résumé L’objectif de cette étude est de caractériser les variations spatiales du transport sédimentaire dans le bassin amazonien brésilien, pour la période 1998–2003, à partir des données décadaires de 11 stations de références, situées sur les principaux tributaires de l’Amazone. Les relations entre les concentrations décadaires de surface et les concentrations moyennes dans la section de jaugeage, provenant des campagnes de mesures HyBAm, sont utilisées pour estimer les flux moyens dans la section. Les taux de transfert spécifiques varient de 10 à 560 t km-2 an-1 et mettent en évidence des variations spatiales significatives entre les parties amont correspondant aux zones montagneuses (eaux blanches), celles des boucliers brésiliens et guyanais (eaux claires) et celles des basses plaines d’inondations (eaux noires). Ensuite, les bilans sédimentaires, de l’amont vers l’aval, des principaux tributaires de l’Amazone ont permis d’identifier des zones de transfert sédimentaire, d’érosion et de dépôt. D’important secteurs de sédimentation ont été identifiés le long du Rio Madeira et de l’Amazone. Ainsi, environ 20% du flux sédimentaire total provenant des Rios Negro, Solimões et Madeira, est déposé en amont d’Óbidos, la dernière et plus importante station de jaugeage sur l’Amazone. La variabilité temporelle de ces processus au pas de temps mensuel est aussi étudiée.Mots clefs Amazonie; Brésil; flux sédimentaire; hydrologie; matières en suspension; sédimentation

The spatial and temporal variability of sediment transport in the Brazilian Amazon basin, based on a regular 10-day sampling programmeAbstract The aim of this study was to characterize the spatial distribution of sediment yields and sediment transfer processes in the Brazilian Amazon basin during the period 1998–2003. For this purpose, the HyBAm project organized a regular 10-day sampling programme at 11 gauging stations on the major tributaries of the Amazon River, for measuring surface suspended sediment concentrations. The relationships between surface concentration and the mean suspended sediment concentration in the gauging section cross section derived from HyBAm field measurements were used to estimate the mean sediment concentration in the cross-section. Combination of these data with the discharge record made it possible to calculate the sediment

loads and the specific sediment yields for these stations. The specific sediment yields ranged from 10 to 560 t km-2 year-1 and evidence significant spatial contrasts between the upstream areas, draining mountainous areas (white water), and the downstream Amazonian flood plain areas (black and clear water). Upstream–downstream suspended sediment budgets for the major tributaries (six stations) were used to identify zones of sediment transfer, erosion and deposition. Important sediment deposition zones were identified along the Amazon River. Thus, about 20% of the suspended sediment yield from the Negro/Solimões/Madeira rivers was deposited upstream of Obidos, the lowest operational gauging station on the Amazon River. The temporal variability of these processes at the monthly time scale is also investigated.Key words Amazon Basin; Brazil; deposition; hydrology; sediment flux; suspended sediment


Storage of fine-grained sediment and associated contaminants within the channels of lowland permeable catchments in the UK

ADRIAN L. COLLINS1, DESMOND E. WALLING1 & GRAHAM J. L. LEEKS2

1 Department of Geography, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, [email protected]

2 Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB, UK

Abstract Storage of fine-grained (<63 m) sediment and associated contaminants within river channels frequently represents an important component of a catchment’s suspended sediment and geochemical budget. It has also been increasingly identified as a cause of degradation of aquatic habitats. Such problems are particularly evident in lowland permeable catchments in the UK, where the groundwater dominated hydrological regimes with a lack of high magnitude flows are conducive to sediment accumulation. In-channel storage of fine-grained sediment and a range of sediment-associated contaminants (C, Cd, Co, Cr, Cu, N, total P, Pb, Zn) has been documented for a total of 45 sampling sites using the findings of a regular bimonthly field sampling campaign in three contrasting lowland permeable catchments. The data demonstrate the spatial and temporal variability of both sediment storage and its contaminant content and provide a means of estimating the total storage of fine-grained sediment and associated contaminants within the main channel system of each study area.Key words channel storage; contaminants; fine-grained sediment; sediment budgets


The use of high-resolution field laser scanning for mapping surface topography in fluvial systems

GEORGE HERITAGE & DAVID HETHERINGTONBuilt and Human Research Institute, School of Environment and Life Sciences, Peel Building, University of Salford, Manchester M5 4WT, [email protected]

Abstract Advances in spatial analytical software allow digital elevation models (DEMs) to be produced which accurately represent landform surface variability and offer an important opportunity to measure and monitor morphological change and sediment transfer across a variety of spatial scales. Many of the techniques presently employed (aerial LIDAR, EDM theodolites, GPS, photogrammetry) suffer coverage or resolution limitations resulting in a trade off between spatial coverage and morphologic detail captured. This issue is particularly important when rates of spatial and temporal change are considered for fluvial systems. This paper describes the field and processing techniques required for oblique laser scanning to acquire 0.01-m resolution digital elevation data of an upland reach of the River Wharfe in the UK. The study site is variable with rapidly changing morphology, diverse vegetation and the presence of water, and these are evaluated with respect to DEM accuracy. Issues regarding location, frequency and distance are discussed with reference to survey accuracy and efficiency for the scanner, and a field protocol is proposed. Data cloud merging was achieved with a high degree of accuracy (sub-centimetre) and scanner accuracy is shown to be very good for exposed surfaces. Vegetation and water decrease the accuracy, as the laser pulse is often prevented from reaching the ground surface or is not returned.Key words field survey; lidar; oblique laser scanning; reach scale mapping; River Wharfe, UK


Daily fine sediment dynamics on an active Alpine glacier outwash plain

DAVID HETHERINGTON1, GEORGE HERITAGE1 & DAVID MILAN2

1 Research Institute for the Built and Human Environment, Centre for Environmental Research, University of Salford, Manchester M5 4WT, UK [email protected]

2 School of Environment, University of Gloucestershire, Cheltenham GL50 4AZ, UK

Abstract Previous studies of channel morphological change have frequently relied upon sparse spatial and temporal data sets, often failing to quantify small-scale changes in channels composed of sand and fine gravel. This study reports the use of a high resolution 3D laser scanner (LMS Z210) in the assessment of fluvial sediment budgets in the proglacial zone of the Ferpècle and Mont Miné glaciers, Switzerland. High resolution (>500 points m-2) data obtained across 4000 m2

of braid plain during the early part of the meltwater season permitted Digital Elevation Models (DEMs) of the bed surface to be produced. Subtraction of successive daily DEMs revealed an overall pattern of erosion in the upstream section of the study reach with deposition occurring in the downstream section. The scanner was able to quantify a major episode of avulsion and medial bar erosion that occurred within the central part of the study reach. Transient lobes and sediment sheets could also be identified at the downstream end of the reach, as could lobe front progradation. Relatively minor changes in channel morphology could also be detected such as bar edge accretion, bank erosion, and chute development.Key words 3D laser scanning; braided river; channel change; channel morphology; DEM;


fine sediment; proglacial


Sediment deposition in riparian ecosystems evaluated by different methods

GERD SPAROVEK, OSNY OLIVEIRA SANTOS BACCHI, MIGUEL COOPER, JOSELINE FILIPPE, VLADIA CORRECHEL & CARLOS EDUARDO PINTO JUHASZUniversity of São Paulo, CP 9, CEP 13.400-970, Piracicaba, SP, Brazil [email protected] Riparian forests play an important role in water conservation. These ecosystems filter and trap sediment produced by erosion and prevent this reaching the waterways. In Brazil, laws protect riparian forests. The established legal widths are determined empirically, based on the width of waterways, with no clear scientific basis. This paper combines three methodological approaches (137Cs, WEPP and soil morphology) to study the effect of a riparian forest in trapping sediment mobilized from upslope sugarcane fields. The study area is located in the south of Brazil. The results will help support Brazilian legislation, by providing a better understanding of the functions of riparian forests in relation to water quality. A good correlation was found between the results provided by the three methodologies. All showed that most of the sediment deposition occurs in the first few metres of the riparian forest and decreases towards its interior. Estimates of soil loss provided by 137Cs and WEPP were similar. The morphology of the sediment and the 137Cs distribution in the profile suggests that deposition occurred during an extreme storm and probably a single erosion event.Key words caesium-137; erosion model; riparian forests; sedimentation; sediment trapping; soil morphology


Sedimentation rates in the Corumbataí River basin, Brazil, derived from 210Pb measurements

DANIEL MARCOS BONOTTO, KELLY YAEKO MIYASHIRO DE ALMEIDA & SAMMY SAMPAIO SIEBER Instituto de Geociências e Ciências Exatas, UNESP-Universidade Estadual Paulista Júlio de Mesquita Filho, Av. 24-A, no. 1515, CP 178, CEP 13506-900, Rio Claro, São Paulo, [email protected]

Abstract Activity profiles of excess 210Pb measured in four sediment cores from the Corumbataí River basin, São Paulo State, Brazil, provided an opportunity to evaluate sedimentation rates that

are helpful for defining appropriate management strategies for the hydrological resources in the basin. This is because Rio Claro city and other municipalities make extensive use of surface waters for drinking water supply. The radiochemical analysis of the sediment cores yielded apparent sediment mass accumulation rates of between 406 and 1014 mg cm -2 year-1 for secondary drainage lines, whereas an intermediate value of 546 mg cm-2 year-1 was found in the Corumbataí River, the main drainage system of the studied area. These values provided estimates of average linear sedimentation rates of between 3.1 and 16.2 mm year -1 that are compatible with field evidence, with the highest value corresponding with an area characterized by accumulation of sediment. Key words Corumbataí River basin, Brazil; erosion; excess 210Pb; physical weathering; radiochemical analysis; sediment; sedimentation rate


Sediment accumulation determined with 210Pb geochronology for Strickland River flood plains, Papua New Guinea

ROLF AALTO1 & WILLIAM DIETRICH2

1 Dept Earth and Space Sciences, University of Washington, Seattle, Washington 98195-1310, USA [email protected]

2 Dept Earth and Planetary Sciences, University of California, Berkeley, California 94720, USA

Abstract The Strickland River is the primary sediment source for the Fly River system, a large tropical river that ranks in the global top 20 for both water and sediment discharge. Over the past decade the Strickland sediment discharge has been gauged at many locations. Comprehensive studies are now underway to study the delivery, transport, and storage of sediment throughout this system. A key question regards the timing and rates of sediment accumulation on the flood plains. Here we present the first geochronological results from an intensive flood plain coring campaign conducted in 2003, outline our procedure for dating PNG sediment with 210Pb geochronology, and summarize some early results from 36 cores. Flood plain accumulation rates appear to be highest upstream near the gravel–sand transition, low in the middle portion of the river, and higher again in the lower reaches of the Strickland near to its confluence with the Fly River. Overall patterns of sedimentation seem to be both spatially consistent, for series of cores collected along single flood plain transects, and temporally uniform in the sense that the nature of accumulation (constant or episodic) has not generally changed over the century of record. Key words lead-210; flood plains; sediment accumulation; Strickland and Fly Rivers, Papua New Guinea


The role of flood plains in the hydrology and sediment dynamics of the Amazon River, Brazil

LAURENCE MAURICE-BOURGOIN1,

JEAN-MICHEL MARTINEZ2, JULIEN GRÉLAUD3,NAZIANO FILIZOLA4 & GERALDO RESENDE BOAVENTURA5

1 IRD, Observatoire Midi-Pyrénées, LMTG, UMR5563, 14 Av. E. Belin, F-31400 Toulouse, [email protected]

2 IRD, UMR5563, Maison de la Télédétection, 500 rue JF Breton, F-34093 Montpellier, France3 ENSEEIHT, 2 rue Charles Camichel, BP 7122, F-31071 Toulouse, France4 ANA, Water National Agency, Setor Policial Area 5, 70610-200 Brasília, DF, Brazil5 University of Brasilia, Geochemistry Laboratory, IG-UnB, 70910-900 Brasília, DF, Brazil

Abstract Flood plains can act as important sinks of sediment and associated heavy metals, such as mercury. In this study, we present an estimate of the role of an Amazonian flood plain in sediment storage. The Curuai flood plain is located on the right bank of the Amazon River, 900 km upstream of the mouth. It is a complex system of more than 30 interconnected lakes, with a maximum inundated area of 2300 km2, representing 0.8% of the total flooded area of the Central Amazon basin. For the period 2000–2003, a mean average sediment deposition of 380 000 (8%) t year-1 was determined using a box model calibrated using a network of gauging, meteorological and sediment monitoring stations operated over a 4-year period and analysis of multi-temporal remote sensing images. This storage represents approximately 0.06% of the total annual sediment flux transported by the Amazon River. The associated mean specific sedimentation rate is approximately 165 t km-2 year-1 if only the flooded area is considered.Key words Amazon River; flood plain; flood plain storage; sediment deposition; suspended sediment


The sediment budgets of hill reservoirs in small catchments in North Africa and the Middle East

JEAN ALBERGEL1, JEAN COLLINET1, YANNICK PEPIN1, PATRICK ZANTE1, SLAH NASRI2, MOHAMED BOUFAROUA3, ABDALLAH DROUBI4 & ABDELAZIZ MERZOUK5

1 IRD, UMR LISAH, 2 place Viala, F-34060 Montpellier, France [email protected]

2 INRGREF BP 10 Ariana 2080, Tunisia3 DG ACTA, Ministry of Agriculture, Av. Charles Nicole, 1002 Tunis, Tunisia4 ACSAD PO Box 2440, Damascus, Syria5 IAV BP 6202 Rabat-Instituts, 10101 Rabat, Morocco

Abstract Global assessments place the loss of reservoir storage by sedimentation at 1% per year. The cost of recovering such storage may be prohibitive. In Mediterranean countries, the situation is worse due to widespread land degradation. Trapping the sediment that comes primarily from the upstream mountain zones in small and relatively inexpensive reservoirs is important. The construction of small dams at different points on the stream network also attenuates flood flows and reduces the erosion potential of storm events, which are often of high magnitude in the Mediterranean region. Within this framework, 32 artificial reservoirs situated in the Tunisian Atlas Mountains, the Rif Mountains of Morocco and the Homs basaltic plateau of Syria, were


chosen to constitute a network for hydrological observations. This paper synthesizes the results obtained from this hydrological network. Guidelines relating to the effective assessment and management of the sediment budgets of small hill reservoirs in the Mediterranean region are provided.Key words dam sedimentation; erosion; Middle East; North Africa; sediment budget; small dams


Erosion of deposits from the pyroclastic flow that occurred on Mt Merapi, Indonesia in July 1998

KATSUO SASAHARA1, MASANORI KANEKO2,MASANOBU TAKEUCHI3, NORIYUKI MINAMI4 & SUBARKAH5

1 Erosion and Sediment Control Research Group, Public Works Research Institute, Republic of Indonesia [email protected]

2 Minister’s Secretariat, Ministry of Land, Infrastructure and Transport, Republic of Indonesia3 Muroran Development and Construction Department, Hokkaido Regional Development Bureau, Ministry of Land,

Infrastructure and Transport, Hokkaido, Japan4 Civil Engineering Department, Nara Prefectural Government, Republic of Indonesia5 Sabo Technical Centre, Republic of Indonesia

Abstract A pyroclastic flow occurred on the southwest flank of Mt Merapi in Indonesia on 19 July 1998. As a result, a large mass of pyroclastic flow deposits filled the valley of the Sat River. In order to understand the gully erosion processes acting on the deposits, we conducted a cross-section survey and took photographs at fixed points within the site. The data obtained from the cross-section survey were used to calculate the sediment yield from gully erosion. The key findings are: (a) Rainfall occurring after the occurrence of the pyroclastic flow caused gully erosion on the deposits. Networks of gullies developed and their cross-sectional size increased rapidly during the first rainy season. (b) The total sediment yield from the gully erosion was estimated to be 680 000 m 3 for the period extending from the occurrence of the pyroclastic flow until February 2000. Most of the sediment yield associated with the gully erosion occurred during the first half of the rainy season. There was no sediment yield from gully erosion during the dry season. (c) the annual specific sediment yield from the pyroclastic flow deposit during the first year was estimated as 1.4 106

m3 km-2 year-1. This value is almost equal to that for the pyroclastic flow deposit on Mt Pinatubo, and is one to two orders of magnitude greater than that of several examples studied on other volcanoes.Key words annual specific sediment yield; cross-section survey; gully erosion; Mt Merapi, Indonesia; pyroclastic flow deposit


Sediment yield scale dependency in the River Eden basin, northwest England

JAMES BATHURST1, PAUL QUINN1, JEREMIE GRAVIER2, JENNY ORANGE3, PASCAL VIVIER4 & SILKE VOGEL5

1 Water Resource Systems Research Laboratory, School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle NE1 7RU, UK [email protected]

2 26 Rue de l’Abreuvoir, F-91370 Verrières le Buisson, France3 Environment Agency, Waterside House, Waterside North, Lincoln LN2 5HA, UK4 Chargé de Mission Plan Loire, DIREN Bourgogne, Antenne de Nevers, Préfecture de la Nièvre, 40 Rue de la

Préfecture, F-58026 Nevers, Cedex, France5 Beller Consult GmbH, Linnéstrasse 5, D-79110 Freiburg, Germany

Abstract A preliminary assessment of the spatial scale dependency of sediment yield from the Eden basin in northwest England is made on the basis of: suspended and bed load yield estimates at scales from 1 to 1370 km2, spot samples of suspended sediment concentration, and a dual resolution mapping exercise in which a generalized soil erosion risk map for the upper Eden (322 km2) is complemented by a high resolution (2 m) map of erosion features and sediment transport pathways in a 5.4-ha farm field. Overall, annual specific total sediment yield decreases as basin area increases: specific bed load yield decreases rapidly but specific suspended load yield may even show a small downstream increase. The spot sampling campaign and the dual resolution mapping exercise suggest that this could reflect the impact of livestock farming in the more lowland areas. The results demonstrate the importance of sediment source and transport pathways in explaining scale dependency in sediment yield.Key words CHASM; erosion map; scale dependency; sediment source; sediment yield


Régime et bilan du flux sédimentaire de l’Amazone à Óbidos (Pará, Brésil) de 1995 à 2003

JEAN LOUP GUYOT1, NAZIANO FILIZOLA2 &ALAIN LARAQUE3

1 IRD-LMTG, Casilla 18-1209, Lima 18, Pérou [email protected]

2 ANA, SPS, Área 5, Quadra 3, Bloco B e L, 70610-200, Brasília-DF, Brésil3 IRD-LMTG, US OBHI, BP 64 501, F-34394 Montpellier Cedex 05, France

Résumé La station hydrométrique de Óbidos sur l’Amazone (Pará, Brésil) draine le plus vaste bassin hydrographique continental (4.8 106 km2), et le débit mesuré à cette station (172 000 m3 s-1) représente 80% des apports hydriques de l’Amazone à l’Océan Atlantique. Depuis 1995, un échantillonnage décadaire de matières en suspension de surface a été organisé afin de connaître la variabilité temporelle du flux sédimentaire de l’Amazone. La calibration de cet échantillonnage superficiel avec les données de 18 campagnes d’exploration du champ des concentrations dans la section jaugée, nous permet de proposer une série continue du flux sédimentaire de l’Amazone à Óbidos, pour la période 1995–2003. Les résultats obtenus montre une forte variabilité saisonnière des flux, non connectée au débit, pour un apport moyen estimé à 810 106 t an-1.Mots clefs Amazone; Brésil; flux sédimentaire; hydrologie

The suspended sediment flux of the River Amazon at Obidos, Brazil, 1995–2003Abstract The hydrometric station on the River Amazon at Obidos gauges the world’s largest river basin (4.8 106 km2), and the mean flow measured at this station (172 000 m3 s-1) represents 80% of the water flux of the Amazon to the Atlantic Ocean. Since 1995, a regular 10-day



programme of surface sampling of suspended sediment has been in operation, with the aim of documenting the temporal variability of the sediment flux of the Amazon. Calibration of the surface samples with the results of detailed sampling of sediment concentrations in the cross section provided by 18 sampling campaigns, has made it possible to generate a continuous record of sediment transport for the River Amazon at Obidos for the period 1995–2003. These data have highlighted the marked seasonality in the sediment flux, unconnected to the variation of discharge, and provide an estimate of the mean annual suspended sediment flux of 810 106 t year-

1.Key words Amazon River; Brazil; hydrology; sediment flux


Suspended sediment fluxes in the large river basins of Brazil

JORGE ENOCH FURQUIM WERNECK LIMA1, WALSZON TERLLIZZIE ARAÚJO LOPES2, NEWTON DE OLIVEIRA CARVALHO3,MAURREM RAMON VIEIRA2 & EUZEBIO MEDRADO DA SILVA1

1 Brazilian Agricultural Research Corporation, Embrapa Cerrados, BR 020, km 18, PO Box 08223, 73310-970 Planaltina, DF, [email protected] Brazilian National Water Agency, ANA, Setor Policial, Área 5, Qd.3, Bl. L, 70610-200, Brasília, DF, Brazil3 Rua Conde de Baependi, 112, ap. 904, 22231-140 Rio de Janeiro, RJ, Brazil

Abstract In Brazil, measurements of suspended sediment transport have been undertaken regularly since 1970 at a number of stations located on the main rivers. The database resulting from those measurements now makes it possible to study the sediment loads of the largest river basins. The primary objective of this paper is to present a preliminary study of the suspended sediment loads of Brazil’s largest river basins, namely the Amazon, Tocantins, São Francisco and Paraná rivers. In view of the available data and the importance of information on sediment loads, this analysis has also been extended to other important basins of the country. The sediment balance along each river was assessed by comparing the mean suspended sediment load of successive measuring stations. Values of mean annual suspended sediment concentration and discharge have been calculated for each station. The total suspended sediment production from the territory of Brazil has been estimated to be 610 106 t year-1.Key words Brazilian rivers; sediment loads; suspended sediment flux; water management; water quality

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