Sediment Dynamics and the Hydromorphology of Fluvial …hydrologie.org/redbooks/a306/P306 Description, contents, abstracts.doc · Web viewThere is evidence for a decline in sedimentation

Sediment Dynamics and the Hydromorphology of Fluvial SystemsEdited by John S. Rowan, Robert W. Duck & Alan Werritty

Analysing the magnitude–frequency relations of erosion, transport and deposition processes is a classic theme within fluvial research. Hydromorphology, dealing with the physical structure and formative hydrological processes of fluvial systems is also an established concept, but has been given new currency by its prominent role within the European Union’s Water Framework Directive. This volume links sediment dynamics to hydromorphology, and by extension to the biogeochemical functioning and eco-hydrology of fluvial systems. Fluvial sediment dynamics are explored over a range of spatial and temporal scales, spanning global and continental-scale flux rates to detailed, process-oriented work on small instrumented catchments, with particular to the role of extreme events. The process links between hydromorphology and ecology are examined and management-related studies are detailed. The utility of sedimentary archives for reconstructing long-term catchment sediment fluxes and elucidating the impact of land use and climate change processes on sediment delivery and biogeochemical cycling is also a focus. The critical issue of residence time, especially in relation to channel storage, is explored. Flume-based hydraulics and microcosm studies of diffuse pollutant behaviour and other recent developments in experiment-led research and modelling are reported.

IAHS Publ. 306 (July 2006)ISBN 1-90150268-6630 + 10 pp. price £96.00

Contents

Preface by John S. Rowan, Robert W. Duck & Alan Werritty v

1 Fluvial Sediment Dynamics and the Importance of Extreme Events

Suspended sediment yield from continents into the World Ocean: spa-tial and temporal variability A. P. Dedkov & A. V. Gusarov

3

Sediment yields in the Exe Basin: a longer-term perspective Anna Harlow, Bruce Webb & Des Walling

12

Estimates and analysis of suspended sediment from a glacierized basin in the Himalayas Pratap Singh

21

Influence of different factors on the sediment yield of the Oka Basin rivers (central Russia) Valentin Golosov

28

Sediment transport during a flushing flow in the lower Ebro River Ramon J. Batalla, Damià Vericat & Antoni Palau

37

Glacial erosion and sediment transport in the Mittivakkat Glacier catchment, Ammassalik Island, southeast Greenland, 2005 Bent Hasholt & Sebastian H. Mernild

45

Flood and sediment transport response to hydrometeorological events of diverse magnitude in the Vallcebre basin, Eastern Pyrenees Montserrat Soler, David Regüés, Jérôme Latron & Francesc Gallart

56

Episodic discharge of coarse sediment in a mountain torrent Richard Johnson & Jeff Warburton

64

The life-span of a small high mountain lake, the Vordere Blaue Gumpe in the Bavarian Alps David Morche, Christian Katterfeld, Sebastian Fuchs & Karl-Heinz Schmidt

72

Output of bed load sediment from a small upland drainage basin in Hong Kong M. R. Peart & L. Fok

82

A volumetric approach to estimate bed load transport in a mountain stream (Central Spanish Pyrenees) N. Lana-Renault, D. Regüés, J. Latron, E. Nadal, P. Serrano & C. Martí-Bono

89

Suspended sediment dynamics for June storm events in the urbanized River Tame, UK D. M. Lawler, I. D. L. Foster, G. E. Petts, S. Harper & I. P. Morrissey

96

Estimating soil erosion and sediment transport in the drainage basin of the proposed Selova Reservoir, Serbia Stanimir Kostadinov, Nada Dragović & Mirjana Todosijević

104

The effect of the “Great Flood of 1993” on subsequent suspended sediment concentrations and fluxes in the Mississippi River Basin, USA Arthur J. Horowitz

110

An underutilized resource: historical flood chronologies, a valuable resource in determining periods of hydro-geomorphic change N. Macdonald

120

Hydromorphological adjustment in meandering river systems and the role of flood events Janet Hooke

127

Sediment erosion, transport and deposition during the July 2001 Mawddach extreme flood event Graham Hall & Roger Cratchley

136

Sediment transport rates of major floods in glacial and non-glacial rivers in Norway in the present and future climate Jim Bogen

148

Evaluating the impacts of impoundment on sediment transport using short-lived fallout radionuclides Francis J. Magilligan, Nira L. Salant, Carl E. Renshaw, Keith H. Nilsow, Arjun Heimsath & James M. Kaste

159

2 The Structure, Functioning and Management of Fluvial Sediment Systems

Variety is the spice of river life: recognizing hydraulic diversity as a tool for managing flows in regulated rivers M. C. Thoms, M. Reid, K. Christianson & F. Munro

169

Multi-scale analysis of island formation and development in the Middle Loire River, France Emmanuèle Gautier & Stéphane Grivel

179

Geometric properties of the River Euphrates, Iraq: the nature of its slope variation Moutaz Al-Dabbas & Mukdad Al-Jabbari

188

Changing use and hydromorphological adjustment in a coastal lagoon–estuarine system, the Ria de Aveiro, Portugal José Figueiredo Da Silva & Robert W. Duck

197

Modelling flow, erosion and long-term evolution of incising channels: managing hydrology and geomorphology for ecology Timothy Norton , Julian Leyland & Stephen Darby

205

The role of sediments in the dynamics and preservation of the aquatic forest in the Nestos Delta (northern Greece) D. Emmanouloudis, D. Myronidis, S. Panilas &G. Efthimiou

214

The use of buffer features for sediment and phosphorus retention in the landscape: implications for sediment delivery and water quality in river basins P. N. Owens, J. H. Duzant, L. K. Deeks, G. A. Wood, R. P. C. Morgan & A. J. Collins

223

Sediment monitoring and sediment management in the Rhine River Stefan Vollmer & Emil Goelz

231

Are flood plain–wetland plant communities determined by seed bank composition or inundation periods? Munique Webb, Michael Reid, Samantha Capon, Martin Thoms, Scott Rayburg & Cassandra James

241

A practical method for the management of road runoff Ingrid Takken, Jacky Croke & Simon Mockler

249

Morphometric analysis of UK lake systems as a compliance tool for the European Water Framework Directive John S. Rowan, Iain Soutar & Geoff E. Phillips

257

Flows that form: the hydromorphology of concave-bank bench forma-tion in the Ovens River, Australia G. J. Vietz, M. J. Stewardson & B. L. Finlayson

267

The diversity of inundated areas in semiarid flood plain ecosystems Orla Murray, Martin Thoms & Scott Rayburg

277

Strategies for reducing sediment connectivity and land degradation in desertified areas using vegetation: the RECONDES project Peter Sandercock & Janet Hooke

287

Evaluating the effectiveness of the Illinois River Conservation Reserve Enhancement Program in reducing sediment delivery Misganaw De-missie, Laura Keefer, Jim Slowikowski, & Kip Stevenson

295

Unravelling the physical template of a terminal flood plain–wetland sediment storage system Scott Rayburg, Martin Thoms & Erin Lenon

304

River sediment/pathogen interactions: importance for policy develop-ment on safe water practices Ian G. Droppo, Steven N. Liss, Declan Williams & Gary G. Leppard

314

Linking pattern and process: the effects of hydraulic conditions on cobble biofilm metabolism in an Australian upland stream Michael Reid & Martin Thoms

322

Combining biology and hydrology—questions from an integrated study of chalk streams Roger S. Wotton & Geraldene Wharton

331

3 Unlocking the Stratigraphic Record

Reservoir sedimentation trends in Ohio, USA: sediment delivery and response to land-use change William H. Renwick & Zachary D. An-dereck

341

Dating of reservoir and pond deposits by the 137Cs technique to assess sediment production in small catchments of the Hilly Sichuan Basin and the Three Gorges Region, China Zhang Xinbao, Qi Yongqing, He Xiubin, Wen Anbang & Fu Jiexiong

348

The role of organic matter on the adsorption of mercury in sediments from Amazon lakes, Brazil Daniel Marcos Bonotto, Marcelo Vergott & Ene Glória Da Silveira

355

Using geochemical stratigraphy to indicate post-fire sediment and nu-trient fluxes into a water supply reservoir, Sydney, Australia William H. Blake, Peter J. Wallbrink, Stefan H. Doerr, Richard A. Shakesby, Geoffrey S. Humphreys, Pauline English & Scott Wilkinson

363

Variation of suspended sediment transport in the Timah Tasoh reser-voir catchment, Perlis, Malaysia: human impacts and the role of tropical storms A. Rahaman Zullyadini & Ismail Wan Ruslan

371

The use of 137Cs and 210Pbex to investigate sediment sources and overbank sedimentation rates in the Teesta River basin, Sikkim Himalaya, India W. Froehlich & D. E. Walling

380

The infilling of a terminal flood plain–wetland complex Robert Cossart, Martin Thoms & Scott Rayburg

389

Sediment budgets and sinks in the Brahmaputra Basin and their agricultural and ecological impacts U. C. Sharma & Vikas Sharma

399

Holocene sediment budgets of the Rhine Delta (The Netherlands): a record of changing sediment delivery Gilles Erkens, Kim M. Cohen, Marc J. P. Gouw, Hans Middelkoop & Wim Z. Hoek

406

Changing fluxes of sediments and salts as recorded in lower River Murray wetlands, Australia Peter Gell, Jennie Fluin, John Tibby, Deborah Haynes, Syeda Ifteara Khanum, Brendan Walsh, Gary Hancock, Jennifer Harrison, Atun Zawadzki & Fiona Little

416

Unravelling flood history using matrices in fluvial gravel deposits Lynne E. Frostick, Brendan Murphy & Richard Middleton

425

The importance of temporal changes in gravel-stored fine sediment on habitat conditions in a salmon spawning stream Ellen L. Petticrew & John F. Rex

434

Pacific salmon and sediment flocculation: nutrient cycling and intergravel habitat quality John F. Rex & Ellen L. Petticrew

442

Sediment storage and transfer in the Mekong: generalizations on a large river Avijit Gupta, S. C. Liew & Alice W. C. Heng

450

River flood plains as carbon sinks D. E. Walling, D. Fang, A. P. Nicholas & R. J. Sweet

460

Investigating the remobilization of fine sediment stored on the channel bed of lowland permeable catchments in the UK Adrian L. Collins & Desmond E. Walling

471

The impact of changes in climate, upstream land use and flood plain topography on overbank deposition Ivo Thonon, Hans Middelkoop & Marcel Van Der Perk

480

A gradient or mosaic of patches? The textural character of inset-flood plain surfaces along a dryland river system Mark Southwell & Martin Thoms

487

The deposition and storage of sediment-associated phosphorus on the flood plains of two lowland groundwater fed catchments Deborah Bal-lantine, Desmond E. Walling & Graham J. L. Leeks

496

4 Experiment-based and Modelling Approaches to Sediment Research

Sediment phosphorus dynamics in tile-fed drainage ditches D. R. Smith, E. A. Warnemuende, B. E. Haggard & C. Huang

507

A framework for predicting delivery of phosphorus from agricultural land using a decision-tree approach Richard Brazier, Michael Schärer, Louise Heathwaite, Keith Beven, Paul Scholefield, Phil Haygarth, Robin Hodgkinson, Des Walling & Paul Withers

514

Nutrient and contaminant enrichment in rural areas of southwest Germany Martin Schwarz & Stephan Fuchs

524

Salinity and erosion: a preliminary investigation of soil erosion on a sa-linized hillslope Mel Neave & Scott Rayburg

531

Analysis of local scour downstream of bed sills: preliminary results of experimental work Donatella Termini

540

Comparison of numerical and experimental study of dam-break induced mudflow Szu-Hsien Peng & Su-Chin Chen

548

MOSESS: a model for soil erosion prediction at small scales Eduardo E. de Figueiredo & Hérbete H. R. C. Davi

556

Predicting erosion patterns using a spatially distributed erosion model with spatially variable and uniform parameters Dirk H. De Boer

564

Importance of watershed lag times in IUSG development Kazimierz Banasik, Mariusz Barszcz & Leszek Hejduk

574

Impacts of land-use changes on sediment yields and water quality within the Nairobi River sub-basins, Kenya Shadrack Mulei Kithiia & Francis M. Mutua

582

Model investigations of the effects of land-use changes and forest damage on erosion in mountainous environments Peter Molnar, Paolo Burlando, Jörg Kirsch & Elke Hinz

589

SWAT model for Integrated River Basin Management with application to the Mekong Basin Riyadh Al-Soufi

601

Modelling the impacts of climate variability on sediment transport Eileen Cashman & Kenneth Potter

611

Effects of rainfall variability and land-use change on sediment yield simulated by SHETRAN Eduardo E. De Figueiredo & James C. Bathurst

620

Key word index 627

Author index 630

Sediment Dynamics and the Hydromorphology of Fluvial Systems (Proceedings of a symposium held in Dundee, UK, July 2006). IAHS Publ. 306, 2006, 3-11.

Suspended sediment yield from continents into the World Ocean: spatial and temporal changeability

A. P. DEDKOV & A. V. GUSAROVFaculty of Geography and Ecology, Kazan State University, Kreml’evskaya Str. 18, Kazan 420008, [email protected]

Abstract Attempts have been made to determine the suspended sediment yield from rivers of the various continents and islands into the World Ocean. Its differentiation into natural and anthropogenic components, and analysis of its contemporary trend variability were undertaken. The total global suspended sediment yield into the World Ocean equals 15.5 × 109 t year-1. The main suppliers are continental Asia and the islands of the west and southwest parts of the Pacific (their contribution to the total global suspended sediment yield into the World Ocean is 73.4%). The least sediment is supplied by Australia (1.1%). Recent human activity has increased suspended sediment yield into the World Ocean by 2.6 times. The largest anthropogenic increase of suspended sediment yield found is on the islands of the west and southwest parts of the Pacific (by 3.7 times) and in Europe (by 3.4 times); the least intensification characterizes South America (by 1.2 times). The analysis of long-term time series of suspended sediment yield shows that during the second half of the 20th century a rising trend of erosion intensity and suspended sediment yield prevailed in South and Central America, East Africa, West Europe, South and South-East Asia and Australia. A reduction of suspended sediment yield took place in East Europe, northwest and east-central parts of Asia and west part of North America. The main factor determining these global scale changes is diverse human activity. Key words anthropogenic factor; changeability; continent; erosion; river basin; suspended sediment yield; trend; World Ocean


Sediment yields in the Exe Basin: a longer-term perspective

ANNA HARLOW, BRUCE WEBB & DES WALLINGSchool of Geography, Archaeology and Earth Resources, Department of Geography, Amory Building, Rennes Drive, Exeter EX4 4RJ, [email protected]

Abstract In the UK, fine sediment is viewed increasingly as a diffuse pollutant due to its role as a vector for the transport of potential contaminants, and in causing siltation, which may have adverse effects on river and estuarine habitats. There is a need, therefore, for river managers to have reliable information on sediment budgets in order to plan measures that will achieve “good” status under the EU Water Framework Directive. As part of a wider sediment-budget investigation in the EU-funded Cycleau Project, detailed records of fine sediment yield over the 10-year period from 1994–2003 have been analysed for the Exe Basin (1500 km2), a principal river system of southwest England. The longer-term average yields in the three major tributaries

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of the Exe Basin are discussed and results of monitoring of sediment loads at a site near the tidal limit over a one-year period confirm the importance of the River Exe in contributing sediment to the Estuary.Key words diffuse pollution; Exe Basin and estuary; longer-term behaviour; suspended sediment yieldsSediment Dynamics and the Hydromorphology of Fluvial Systems (Proceedings of a symposium held in Dundee, UK, July 2006). IAHS Publ. 306, 2006, 21-27.

Estimates and analysis of suspended sediment from a glacierized basin in the Himalayas

PRATAP SINGHNational Institute of Hydrology, Roorkee 247 667, Uttar.Anchal, [email protected]; [email protected]

Abstract The study deals with the sediment delivery pattern of a highly glacierized basin, the Gangotri Glacier basin (total area 556 km2, glacierized area 286 km2, elevation range 4000–7000 m) located in the Himalayan region. To carry out this study, suspended sediment samples and discharge data were collected near the snout of the glacier (4000 m a.s.l.) for four consecutive melt seasons 2000–2003 (May–October). The monthly distribution of suspended sediment concentration (SSC) and its variability from year to year has been examined. Mean monthly SSC for May, June, July, August, September and October was found to be 1942, 2063, 3658, 2551, 734 and 136 mg L-1, respectively, showing maximum SSC in melt water in July followed by August. It was found that cumulative percentage delivery of SSC precedes discharge throughout the melt season. About 59–64% of the sediment passed through the channel by the time 50% of the total discharge had passed. Average seasonal values of sediment yield were estimated for the study basin.Key words Gangotri Glacier; glacierized basins; melt season; suspended sediment concentration; suspended sediment yield


Influence of different factors on the sediment yield of the Oka basin rivers (central Russia)

VALENTIN GOLOSOV Laboratory for Soil Erosion and Fluvial Processes, Faculty of Geography, Moscow State University, GSP-2, 119992, Moscow, [email protected]

Abstract In order to investigate links between basin/land-use characteristics and sediment fluxes of rivers within the Oka River basin, a database has been compiled from observations obtained at 25 gauging stations located in different parts of the basin. Relatively high correlations have been found between sediment yield from basin hillslopes and river sediment yield for: (i) rivers of the forest and northern part of forest-steppe zones (r2 = 0.50); and (ii) rivers of forest-steppe zones (r2

= 0.52). A linear positive relationship (r2 = 0.71) has been found between sediment delivery ratio and weighted average gradient of river channel separately for the large river basins and small river basins of the forest zone. A negative relationship between sediment delivery ratio and

forested area within basins is found separately for the small (S < 2500 km2) rivers and large rivers of the Oka River basin. The influence of other factors as well as the problem of small river aggradation is also discussed.Key words erosion; gauging station; river aggradation; Russia; sediment yield


Sediment transport during a flushing flow in the lower Ebro River

RAMON J. BATALLA1,2, DAMIÀ VERICAT1,2 & ANTONI PALAU1,3

1 University of Lleida, Av. Alcalde Rovira Roure 177, E-25198 Lleida, [email protected] Forestry and Technology Center of Catalonia, Pujada del Seminari s/n, E-25280 Solsona, Spain3 Direction of Environment and Sustainable Development. ENDESA, Carretera de Tarragona km. 89.300 (Magraners), E-25008 Lleida, Spain

Abstract This study describes the sediment transport which occurred during the double peak flushing flow of November 2003 in the gravel-bedded lower Ebro River (northeast Spain). The experimental release was designed and undertaken to control the excess of aquatic vegetation in the river channel downstream from dams. Macrophytes cause problems to several water users, especially to the hydroelectric and the nuclear power plants located in the vicinity of the river. Observations show a distinct pattern of sediment transport between the two flood peaks owing to the particular channel conditions (i.e. exhaustion of fine sediment and removal of the surface layer). Gravel was mobilized during the flood. However, since bed load rates were low and the flood duration was short, no incision was caused in the river bed. In spite of that, large quantities of macrophytes were removed. The combination of hydraulic and sedimentary parameters during the designed flood maximized the ecological and management benefits of the experimental release without significant adverse geomorphological impacts on the river channel. Key words dams; Ebro River; flushing flow; macrophytes; sediment transport


Glacial erosion and sediment transport in the Mittivakkat Glacier catchment, Ammassalik Island, southeast Greenland, 2005

BENT HASHOLT & SEBASTIAN H. MERNILDInstitute of Geography, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, [email protected]

Abstract A station for monitoring suspended sediment concentration with high time resolution was developed and located near the outlet from the Mittivakkat Glacier in order to monitor “true” glacial erosion. Sediment transport at 10 minute intervals for a 64-day period of the 2005 melt season was determined for the Mittivakkat Glacier catchment, southeast Greenland. The total transport for the whole period was 17 800 t based on measurements with an OBS3 (optical

backscatter) sensor and 17 300 t with a Partech IR500 (infrared transmissometer), with maximum transport values of 25 and 24 t 10-min-1, respectively. The results confirm earlier measurements of specific transport of more than 1000 t km-2 year-1 from the Mittivakkat Glacier. Comparison with concentrations obtained from manual suspended sediment samples from a station near the outlet to the sea, confirm results based on earlier Caesium-137 inventories indicating that sediment is trapped in the proglacial valley between the glacier and the sea. The material produced from glacial erosion is mainly released in late July–August when the glacier drainage system is fully developed and enough melt water is available for transport.Key words Ammassalik Island; glacial erosion; Greenland; sediment transport


Flood and sediment transport response to hydrometeorological events of diverse magnitude in the Vallcebre basin, Eastern Pyrenees

MONTSERRAT SOLER1, DAVID REGÜÉS2, JÉRÔME LATRON2 & FRANCESC GALLART1

1 Institute of Earth Sciences Jaime Almera, CSIC, Lluís Solé sabarís s/n, Barcelona, E-08028 [email protected] 2 Pyrenean Institute of Ecology, CSIC, Montañana 1005, Zaragoza, E-50059 Spain

Abstract Precipitation, discharge and suspended sediment concentrations were continuously measured for ten hydrological years (1995–2004), in the Ca l’Isard sub-basin (1.32 km 2) of the Vallcebre experimental catchments, Spain. The daily precipitation record is 22 years long. When all the events were analysed, the diverse variables considered (precipitation depth, peak discharge, runoff depth, and sediment load) showed significant Spearman rank correlation coefficients among them. Nevertheless, when the major events, corresponding to the upper 10%, were selected, several of these variables were poorly correlated, and the Spearman coefficients strongly dependant on the variable used for selecting the events. The results confirm the complexity of the sediment processes in these catchments, and demonstrate that the ranking of events according to precipitation characteristics may be adequate for sediment transport purposes only for the main events.Key words badlands; magnitude-frequency; Mediterranean climate; recurrence interval; sediment transport


Episodic discharge of coarse sediment in a mountain torrent

RICHARD JOHNSON1 & JEFF WARBURTON2

1 School of Natural Resources, University of Central Lancashire, Penrith Campus, Penrith, Cumbria CA11 0AH, UK [email protected] 2 Catchment, Hillslope and River Science Research Group, Department of Geography, Durham University, Science Laboratories, South Road, Durham DH1 3LE, UK

Abstract Direct observations of coarse sediment transport in mountain streams are rare. This paper describes a unique, high resolution record of coarse sediment flux from a steep, mountain torrent in the English Lake District, UK. A recording raingauge at the head of the torrent and a sediment trap (~14-day resolution) provide a detailed record which extends from October 2001 to April 2005. Comparison between the sediment flux and rainfall series demonstrates the importance of precipitation extremes in triggering coarse sediment delivery. Typically one major sediment evacuation event occurs each year producing a distinct episodic output of coarse sediment. These events have similar yields and occur with an apparent regularity. Grain-size analysis of trapped sediment suggests a supply and exhaustion signal, and the differential role of processes across the sediment–water flow spectrum.Key words mountain torrent; rainfall extremes; sediment yield; UK


The life-span of a small high mountain lake, the Vordere Blaue Gumpe in the Bavarian Alps

DAVID MORCHE1, CHRISTIAN KATTERFELD2, SEBASTIAN FUCHS1 & KARL-HEINZ SCHMIDT1

1 Department of Geography, Martin-Luther-University Halle-Wittenberg, D-06099 Halle, Germany [email protected] Department of Geography, University of Basel, Klingelbergstrasse 27, CH-4056 Basel, Switzerland

Abstract The Reintal valley in the Wetterstein Mountains in Upper Bavaria has been dammed by large rockslide deposits in some localities. Behind one of the dams a small lake, the Vordere Blaue Gumpe, was still in existence until 23 August 2005. The lake was a natural sediment sink, decoupling an area of about 1.6 km2 from fluvial sediment export out of the sediment cascade of the Reintal valley. The bergsturz event occurred about 200 years ago. It was dated by evaluating historical maps, paintings, photographs and sketches. Present research is focused on multi-temporal changes of the alluvial deposits of the delta by analysis of aerial photos and geodetic surveying. Volume loss of the lake is closely related to bed load input during extreme events and shows the geomorphic coupling of hillslope and channel systems. From regression analyses of the annual volumetric change of the lake volume, the life-expectancy of the lake was estimated to be about 15 years, before an extreme high magnitude event in August 2005 filled the lake completely with sediment. Now, after the filling of the lake, with the coupling of the catchment area of the Vordere Blaue Gumpe to downstream fluvial sediment export, higher solid load transport is expected in the lower reaches with possible negative effects on infrastructure. Key words Bavarian Alps; bed load; fluvial sediment transport; geodetic surveying; geomorphic coupling; high magnitude event; lake sedimentation


Output of bed load sediment from a small upland drainage basin in Hong Kong

M. R. PEART & L. FOKDepartment of Geography, The University of Hong Kong, Hong Kong

[email protected]

Abstract Sediment has been removed from a “natural” bed load trap in a small upland drainage basin in Hong Kong and from 1989 to 2003 annual yield has been determined. For the 15-year observation period the median yield was 607 kg with a highest yield of 3897 kg. Five years (1989, 1993, 1994, 1997 and 1999) recorded annual yields of over 2000 kg. Scattergraphs of annual bed load yield against annual maximum 24 and 48 h rainfall reveal a positive association with correlation coefficients of 0.69 and 0.67, respectively. Extreme rainfall events, as defined by high return periods, may be associated with annual bed load yields that are well above the median for the 15 years of observation.Key words bed load; rainfall; return period


A volumetric approach to estimate bed load transport in a mountain stream (Central Spanish Pyrenees)

N. LANA-RENAULT, D. REGÜÉS, J. LATRON, E. NADAL, P. SERRANO & C. MARTÍ-BONOInstituto Pirenaico de Ecología-CSIC, Campus de Aula Dei, Avda. Montañana 1005, 50.192 Zaragoza, [email protected]

Abstract In the Arnás stream (Central Spanish Pyrenees) bed load transport is an important process since the channel is totally armoured with coarse particles (D50 = 100 mm). Discharge and suspended sediment transport are continuously measured at the outlet of the catchment. Bed load is retained in a trap located before the weir, though during large floods this system is insufficient. In such cases the trap is overfilled, favouring coarse material accumulation a few meters upstream of the outlet. In order to quantify bed load transport, a 3 m long profilometer was built to survey an 11 m2 area of bed load accumulation. The volume of bed load transport during each flood is estimated from seven profiles measured every 60 cm. Data from seven events are presented. It is shown that the volume of accumulated material does not depend on flow duration or effective runoff but on the peak flow.Key words bed load transport; experimental catchment; flow event; profilometer


Suspended sediment dynamics for June storm events in the urbanized River Tame, UK

D. M. LAWLER1, I. D. L. FOSTER2,3, G. E. PETTS1, S. HARPER2 & I. P. MORRISSEY1

1 School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, [email protected] Centre for Environmental Research and Consultancy, School of Science and the Environment, Coventry University, Priory Street, Coventry CV1 5FB, UK


3 Geography Department, Rhodes University, Grahamstown 6140, South Africa

Abstract Few studies of urban water quality storm-event dynamics have been conducted at the sub-catchment scale, though most models assume a “first-flush”, positive hysteresis response. This paper reflects on the appropriateness of the first-flush model for summer (June) storms, using high-resolution flow, turbidity and water quality data from the highly urbanized River Tame head-water system, central England. Discharge responded very quickly to storm precipitation, and turbidity events exceed 500 FTU 60 times per annum. However, “first-flush” responses were rare, and turbidity normally peaked after the flow maximum, leading to anticlockwise hysteresis, reinforced by lengthy turbidity “tails”. This suggests limited sediment exhaustion. Many responses probably relate to triggering of Combined Sewer Overflows and/or Waste Water Treatment Works, which occur late in storms when capacities are exceeded, and is consistent with concurrent ammonia increases and DO decreases. Prolonged turbidity responses can raise suspended solids loads above predicted levels, increase ecological stress, and lead to complications for sediment budget studies. A re-examination of the first-flush model is overdue.Key words hysteresis; storm event; suspended sediment; suspended solids; turbidity; urban river; water quality


Estimating soil erosion and sediment transport in the drainage basin of the proposed Selova Reservoir, Serbia

STANIMIR KOSTADINOV, NADA DRAGOVIĆ & MIRJANA TODOSIJEVIĆFaculty of Forestry, Belgrade University, Kneza Višeslava 1, 11030 Belgrade, Serbia and [email protected]

Abstract In recent years construction work has been performed on the River Toplica with the aim of building a dam that will form the water supply for reservoir Selova. The basic purpose is water supply, but flood protection, sediment retention, production of hydro-electricity, breeding of fish, irrigation and tourism are important secondary benefits. This paper describes the headwaters of the River Toplica drainage basin and the nature and extent of its erosion and sediment transport processes. There are no measured data regarding sediment transport in the drainage basin, so the evaluation of sediment transport and potential reservoir siltation was based on empirical methods developed using research and direct measurements in experimental drainage basins elsewhere in Serbia.Key words headwater; reservoir siltation; sediment transport; soil erosion; water reservoir


The effect of the “Great Flood of 1993” on subsequent suspended sediment concentrations and fluxes in the Mississippi River Basin, USA

ARTHUR J. HOROWITZ


US Geological Survey, Peachtree Business Center, Suite 130, 3039 Amwiler Road, Atlanta, Georgia 30360, USA [email protected]

Abstract During the spring/summer of 1993, the upper Midwestern USA experienced unusually heavy precipitation (200–350% above normal). More than 500 gauging stations in the region were simultaneously above flood stage, and nearly 150 major rivers and tributaries over-topped their banks. This was one of the costliest floods in the history of the USA, and came to be known as the “Great Flood of 1993”. An examination of the long-term daily sediment record for the Mississippi River at Thebes, Illinois (representing the middle, or lower part of the upper basin), indicates that the flood had a severe and long-lasting impact on subsequent suspended sediment concentrations (SSC) and annual suspended sediment fluxes in the basin. At Thebes, pre-1993 (1981–1992) median discharge and SSC were about 5400 m3 s-1 and 304 mg L-1, respectively; whereas, post-1993 (1994–2004) median discharge and SSC were about 5200 m3 s-1 and 189 mg L-1, respectively. Clearly, the 1993 flood removed substantial amounts of “stored” bed sediment and/or readily erodible flood plain deposits, eliminating a major source of SSC for the Thebes site. Examination of additional, but discontinuous sediment records (covering the period from 1981–2004) for other sites in the basin indicates that current post-flood declines in SSC and suspended sediment fluxes range from a low of about 10% to a high of about 36%. Key words Mississippi River Basin; suspended sediment concentration; suspended sediment fluxes


An underutilized resource: historical flood chronologies a valuable resource in determining periods of hydro-geomorphic change

N. MACDONALDInstitute of Geography and Earth Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3BD, Wales, UK [email protected]

Abstract Floods are recognized as important geomorphic drivers within the hydrological system, but short hydrological records can inhibit the application of hydrological data in determining periods of hydrologically driven geomorphic change. This paper details the construction of a series of historical flood chronologies, based on some of the largest catchments within the UK. Flood chronologies have been constructed for eight large UK rivers; the selected sites provide a network covering many of the largest river catchments in the UK centred on cities and towns with long detailed documentary flood histories. These chronologies offer an opportunity to assess the long-term patterns of flooding, indirectly determining likely periods of increased geomorphic activity. This research represents the first coherent large-scale analysis undertaken of historical multi-catchment flood chronologies, providing an unparalleled network of sites across the country, permitting analysis of the spatial and temporal distribution of historical flood patterns on a national scale. Key words catchments; flood chronology; frequency; historical; national; UK



Hydromorphological adjustment in meandering river systems and the role of flood events

JANET HOOKEDepartment of Geography, University of Portsmouth, Buckingham Building, Lion Terrace, Portsmouth PO1 3HE, [email protected]

Abstract This paper takes a selection of meandering rivers in the UK to address issues of morphological adjustment and change. The occurrence of peak flow events over recent decades is analysed for patterns and trends. Certain hydrological phases are identifiable. Changes in morphology and activity of the channels are examined through repeat field and aerial photograph mapping and some detailed observations over a period of 20 years. These show major variations, some of which appear to be related to discharge fluctuations. The differing impact of the highest floods within the period of record is demonstrated. The state of the system, particularly the degree of meander development, is of crucial importance. A seasonal difference in the impact of high flow events is also detected. Relationships between morphological changes and discharge characteristics are complex and the effects of other factors, particularly growing season and ramped effects of growth of vegetation may be significant.Key words channel changes; channel migration; discharge fluctuations; erosion; floods; hydromorphology; river meanders; temperature changes


Sediment erosion, transport and deposition during the July 2001 Mawddach extreme flood event

GRAHAM HALL & ROGER CRATCHLEYCentre for Arid Zone Studies and School of Agricultural and Forest Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, Wales, UK [email protected]

Abstract Modelling has been carried out to investigate sediment redistribution during an estimated 300-year maximal flood event on the River Mawddach, North Wales, on 3 July 2001. Rainfall distribution during the storm has been deduced from a combination of raingauge readings and MM5 mesoscale meteorological modelling. The limited hydrograph data available has been augmented with synthetic hydrographs generated by HEC-1 software. A GSTARS sediment model provides estimates of erosion, transport and deposition during and after the flood event for size classes ranging from fine sand to boulders. Simulation results, consistent with field observations, indicate that erosion predominated throughout the river system, with sand grade material derived from glacial and periglacial deposits making up the majority of the river sediment load. Severe changes in valley profile occurred, particularly at sites where human activity had modified the equilibrium form of the river channel. Success of the modelling activity is heavily dependent on accurate mesoscale rainfall data and sub-catchment hydrographs. Key words cross profile erosion; extreme rainfall; North Wales; sediment transport modelling


Sediment transport rates of major floods in glacial and non-glacial rivers in Norway in the present and future climate

JIM BOGENNorwegian Water Resources and Energy Directorate, PO Box 5091, Maj. 0301, Oslo, [email protected]

Abstract This paper considers possible sediment transport impacts in both glacial and non-glacial rivers in Norway from climate scenarios predicted by the RegClim (2005) project. The significance of high magnitude, low-frequency events as sediment transport agents is discussed on the basis of sediment transport measurements during major floods in various types of rivers. It was found that suspended sediment concentrations and volumes were dependant on the availability of sediments, the type and character of the erosion processes, and the temporal development of the flood. Measurements in a glacier outlet river during a flood of 100-year recurrence interval gave a high sediment load, but of the same order of magnitude as the mean. The reason for this is attributed to a limited availability of sediment for erosion in the subglacial channels. In reaches downstream from the glaciers and in non-glacial rivers, measurements during floods of 100- to 200-year recurrence indicate transport rates of about 30–40 times the mean of the preceding years. Due to the predicted increase in precipitation high-lying glaciers may advance in the first part of the 21st century. As a result of the continued increase in temperatures a general recession will occur and most glaciers will have disappeared by 2100. This will probably increase the formation of glacier dammed lakes that may generate lake outbursts. Large magnitude floods are found to be an important controlling factor of ravine development in the clay areas. It is thus anticipated that the equilibrium of the ravines will be altered by climate change because of the increase in flood frequency and magnitude. As a result, an increase in vulnerability to clay slides may take place.Key words climate change; erosion; major floods; sediment transport


Evaluating the impacts of impoundment on sediment transport using short-lived fallout radionuclides

FRANCIS J. MAGILLIGAN1, NIRA L. SALANT2, CARL E. RENSHAW3, KEITH H. NISLOW4, ARJUN HEIMSATH3 & JAMES M. KASTE3

1 Department of Geography, Dartmouth College, Hanover, New Hampshire 03755, [email protected] Department of Geography, University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada3 Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA4 US Department of Agriculture Forest Service, University of Massachusetts, Amherst, Massachusetts 02125, USA

Abstract Dams greatly influence water and sediment discharge regimes and can have significant impacts on channel morphology and sediment storage. By using the short-lived fallout radionuclide 7Be (t1/2 = 53.4 days) as a tracer of fine (~0.25–2 mm) bed material load transport, we capture the sedimentological and geomorphic impacts of the Union Village Dam, located on the Ompompanoosuc River, in eastern Vermont, USA. We measured 7Be activities in approximately monthly samples from streambed sediments in a regulated stream and an unregulated control stream. In the regulated stream our sampling spanned an array of management conditions during the annual transition from flood control in the winter and early spring to run-of-the-river operation from late spring to autumn. Because sediment stored behind the dam during the winter quickly became depleted in 7Be activity, it became possible to track this plug of “dead” sediment as it moved downstream. Measured average sediment transport velocities (30–80 m day-1) exceed those typically reported for bulk bed-load transport and are remarkably constant across varied flow regimes, possibly due to corresponding changes in the bed sand fraction. Results also show that the length scale of the downstream impact of this dam management (winter pool and summer run-of-the river with minimal sediment trapping efficiency) on sediment transport can be short (~1 km); beyond this distance the sediment trapped by the dam is replaced by new sediment from point bars, tributaries and other downstream sources. The benthic community structure indicates significantly greater abundance of caddisflies downstream of the dam due primarily to a lack of bed disturbance following impoundment.Key words dams; radionuclides; sediment; tracers


Variety is the spice of river life: recognizing hydraulic diversity as a tool for managing flows in regulated rivers

M. C. THOMS, M. REID, K. CHRISTIANSON & F. MUNROWater Research Lab, eWater CRC, University of Canberra, Australia Capital Territory 2601, [email protected]

Abstract Biodiversity in river ecosystems is supported by physical diversity in the river environment. Physical diversity is, in part, defined by hydraulic characteristics such as water depth, flow velocity, and turbulence. Establishing the relationship between discharge and hydraulic character is an important step in the process of managing flow to maintain and enhance physical and biological diversity within these systems. This paper considers the relationship between discharge and hydraulic character in the regulated lowland section of the River Murray, Australia. Spatial variation in hydraulic conditions was determined by mapping hydraulic character at three flow discharges: 2000, 3000 and 9000 ML day-1 in three reaches of the River Murray. These data were used to define patches of distinct hydraulic conditions, primarily using depth-averaged flow velocity. The physical character and spatial arrangement of these patches varied according to reach and discharge. This study shows that spatial flow variability can be used as a management tool to maximize habitat diversity in regulated rivers. Key words ADP; flow; River Murray; patches; riverine ecosystem; spatial-temporal variability


Multi-scale analysis of island formation and


development in the Middle Loire River, France

EMMANUÈLE GAUTIER & STÉPHANE GRIVEL University Paris 8, Dept of Geography and CNRS Laboratoire de Geographie Physique, 1 Place A. Briand, F-92195 Meudon Cedex, [email protected]

Abstract Vegetated islands in the river represent very specific fluvial landforms dominating the landscape of the middle Loire River. Our aim is a better understanding of island formation, planform evolution channel adjustment over different spatial and time scales. A number of approaches were adopted. First, the analysis of historical maps and aerial photographs reveals the recent development of islands, allowing the determination of different types of islands associated with specific evolution mechanisms and mobility rates. The second approach is based on the comparison of cross-section profiles of the river bed at multi-decadal time scales. This part of the study used precise topographic surveys and sediment trapping systems coupled with grain-size analyses to evaluate the annual deposition and erosion. The impact of two floods of different magnitudes, with return periods of 5 and 30 years, was also investigated.Key words environmental change; floods; fluvial islands; France; Loire River; sedimentation rates


Geometric properties of the River Euphrates, Iraq: the nature of its slope variation

MOUTAZ AL-DABBAS & MUKDAD AL-JABBARICollege of Science, University of Baghdad, Jadiriya, Baghdad, [email protected]

Abstract The results of a bathymetric survey carried out during 1999, which yielded 152 cross-sections along the Euphrates River within Iraqi territory, was used for slope measurements. The values of slope coefficients were calculated at separations of 5 km. The slope coefficients were calculated first using the water surface method and secondly using the river bed method. The variation of the slope values along the river course were plotted and it was sub-divided into nine reaches according to changes in the slope values that represent the topographic nature of the river course or according to the existence of artificial structures such as irrigation barrages. The results of the slope variation within each reach were studied and the representative equation was determined with comparisons of the two methods of slope measurement.Key words Euphrates River; Iraq; river bed; slope coefficient; water surface


Changing use and hydromorphological adjustment in a coastal lagoon–estuarine system, the Ria de Aveiro, Portugal


JOSÉ FIGUEIREDO DA SILVA1 & ROBERT W. DUCK2

1 Departamento de Ambiente e Ordenamento, Universidade de Aveiro, 3810-193 Aveiro, [email protected] Department of Geography, University of Dundee, Dundee DD1 4HN, Scotland

Abstract Today the Ria de Aveiro of northern Portugal has a hydromorphological regime in which river influence is limited to periods of flood. For most of the annual cycle, tidal currents and wind waves are the major forcing agents in this complex coastal lagoon–estuarine system. The system has evolved over two centuries from one that was naturally fluvially dominant to one that is today tidally dominant. Human influence was a trigger for these changes, starting in 1808 when its natural evolution was halted by the construction of a new inlet/outlet channel through the mobile sand spit that isolates it from the Atlantic Ocean. In consequence, tidal ranges in the lagoon increased rapidly from ~0.1 m to >1 m and continued to increase, as a result of continued engineering works and dredging, today reaching ~3 m on spring tides. Hydromorphological adjustments that have taken place include the deepening of channels, an increase in the area of inter-tidal flats, regression of salt marsh, increased tidal propagation and increased saline intrusion. Loss of once abundant submerged aquatic vegetation (SAV), due to increased tidal flows, exacerbated by increased recreational activities, has been accompanied by a change from fine cohesive sediments to coarser, mobile sediments with reduced biological activity.Key words human use; hydromorphological regime; Ria de Aveiro, Portugal; seagrasses; sediments


Modelling flow, erosion and long-term evolution of incising channels: managing hydrology and geomorphology for ecology

TIMOTHY NORTON1, JULIAN LEYLAND2 & STEPHEN DARBY2

1 Environment Agency, Guildbourne House, Chatsworth Road, Worthing BN11 1LD, UK [email protected] School of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK

Abstract The Isle of Wight Chines are deep, canyon-like features, caused by small streams incising through soft cliffs as they flow to the sea. The actively eroding Chines provide unique habitats of significant ecological value. The long-term geomorphological evolution of the features is of importance when making managerial decisions and implementing policies. A conceptual model of Chine evolution is being formulated in conjunction with ecological and invertebrate surveys, in an attempt to predict the various morphological and ecological stages of Chine development. In a Habitats Directive review of abstraction consents by the UK Environment Agency, the effects of varying abstraction rates were assessed. Licensed abstractions were predicted to reduce natural erosion by up to 90%. The details of this assessment and the long term evolution model of the Chines are presented within the framework of managing the Chines for the sustainability of ecology.Key words Chines; conceptual; ecology; jet testing; management; modelling


The role of sediments in the dynamics and

preservation of the aquatic forest in the Nestos Delta (northern Greece)

D. EMMANOULOUDIS1, D. MYRONIDIS1, S. PANILAS2 & G. EFTHIMIOU1

1 Department of Forestry and Natural Environment Management, Technological Educational Institute of Kavala, Annex Drama 66100, Drama, [email protected] Public Power Corporation, General Directorate of Hydropower Works, Region of Eastern Macedonia, Greece

Abstract The River Nestos empties into the Aegean Sea creating its delta. An aquatic forest of exceptional natural beauty has developed on this delta, which is considered to be the largest in the Balkans. Today, this forest is endangered due to various reasons. However, the most recent and important one is a major decrease in the sediment quantity that discharges into the territory of both the delta and the forest, because of the construction of two large hydropower dams. The purpose of this paper is to investigate the sediment dynamics in the bed and delta of the River Nestos, before and after the construction of the dams, respectively. The research was carried out using satellite imagery and GIS modelling, demonstrating that declining water supply and sediment fluxes led to significant changes in the area (>200 ha) and shape of the delta, causing functional impairment and serious degradation of the aquatic forest.Key words aquatic forest; delta; GIS model; satellite image; sediment dynamics


The use of buffer features for sediment and phosphorus retention in the landscape: implications for sediment delivery and water quality in river basins

P. N. OWENS1, J. H. DUZANT2, L. K. DEEKS1, G. A. WOOD2, R. P. C. MORGAN2

& A. J. COLLINS3

1 National Soil Resources Institute (NSRI), Cranfield University, North Wyke Research Station, Okehampton, Devon EX20 2SB, [email protected] NSRI, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK3 Landcare Research, Massey University, Palmerston North, New Zealand

Abstract There is a variety of buffering features within the landscape that can be used to trap sediment and associated contaminants such as phosphorus (P), thereby helping to reduce sediment and P delivery to watercourses. Astroturf mats were placed within contrasting buffer features at nine sites within the River Parrett basin in England. Mats collected sediment at only four of the sites during the sampling period due to limited erosion and/or sediment by-passing the mats at most sites. For those sites where mats collected sediment, which tended to be either grass strips and/or hedges at mid- or bottom-field locations, there was a considerable range in sedimentation with average values for the sites ranging from 0.07 to 9.1 g cm -2 (average for all mats = 1.7 g cm-2). Most of the sediment was sand-sized material (average for all mats: %sand = 82%, d50 = 123 µm). The site-average total-P content of the <63-µm fraction of the deposited sediment ranged between 559 and 1185 mg kg-1. Comparison between mats located at the front and back of one of the sites shows that more sediment was trapped at the front than at the back,

although the particle size and total-P content were similar at both locations. The results suggest that different types of buffers are more effective than others in reducing sediment and P delivery to watercourses, and that the strategic location and careful design of buffer features is a key factor in their effectiveness. Key words buffer features; particle size; phosphorus; sediment; water quality


Sediment monitoring and sediment management in the Rhine River

STEFAN VOLLMER & EMIL GOELZFederal Institute of Hydrology, BfG, PO Box 200253, D-56002 Koblenz, [email protected]

Abstract Long-term records of permanent monitoring stations on the Rhine River are an excellent base from which to quantify the input of suspended sediment from the large tributaries and to estimate the effect of impounding on the sediment budget of the Upper Rhine. The decrease of suspended load downstream of the Iffezheim barrage is clearly related to the completion of the impoundment chain in the 1970s. Recently about 100 000 t of fine-grained sediments were dredged in the backwater of the Iffezheim barrage and relocated downstream into the free flowing river. Due to a comprehensive monitoring programme, the impact of this measure on sediment concentration could be traced downstream over tens of kilometres. Furthermore, the effect of a very high sediment input due to an extreme precipitation event in Switzerland in August 2005 was analysed in detail. A preliminary attempt to reconstruct the propagation of the sediment wave has brought new insight into the sedimentation processes along the Upper Rhine and helps to understand the potential effects of climate changes on the suspended load of the Rhine River. Key words climate change; contaminated sediments; dredging; sedimentation; suspended load


Are flood plain–wetland plant communities determined by seed bank composition or inundation periods?

MUNIQUE WEBB1, MICHAEL REID1, SAMANTHA CAPON2, MARTIN THOMS1, SCOTT RAYBURG1 & CASSANDRA JAMES3

1 Water Research Lab, University of Canberra, Australian Capital Territory, [email protected] School of Biological Sciences, eWater CRC, Monash University, Melbourne, Victoria, Australia 3 Centre for Riverine Landscapes, Nathan Campus, Griffith University, Nathan, Queensland, Australia

Abstract Vegetation zonation patterns are a common feature in flood plain–wetland complexes and are important to the biodiversity and functioning of such systems. The purpose of this paper is to identify links between water regime, seed bank and the establishment of zoned vegetation


communities in a series of small distributary channels within the Narran Lakes flood plain–wetland complex, eastern Australia. Seed bank material from three distinct plant community zones within three distributary channels were collected and subjected to five inundation treatments over a period of 12 weeks to test the effects of location and inundation regime on the abundance of seedlings, species richness and species assemblages. The results of this study indicate that the water regime determines which species germinate and the seed bank influences the abundance of plants to emerge. This study provides insight into the implications of changing flooding regimes on plant community composition in flood plain–wetland systems.Key words community composition; flood plain; inundation regime; vegetation patterns


A practical method for the management of road runoff

INGRID TAKKEN, JACKY CROKE & SIMON MOCKLER School of Physical, Environmental and Mathematical Sciences, UNSW@ADFA, Northcott Drive, Canberra, Australian Capital Territory 2601, Australia [email protected]

Abstract In this paper we outline a conceptual and methodological approach to evaluating the impacts off unsealed forest roads on in-stream water quality based upon the principal of hydrological connectivity. The methodology is based on the Vbt5 model of Hairsine et al. (2002) and makes use of simple empirical relationships that only require input data that are generally available or relatively easily to obtain, such as the road contributing area to drains and the distance from drain outlets to the streams. Using a plantation forestry catchment in the Australian Capital Territory, we demonstrate that the degree of connectivity along a road network is affected by the spatial distribution of the runoff delivery pathways. Furthermore, we illustrate how the methodology can be used to extract practical guidelines for appropriate drain spacing and to develop risk assessment maps to assist in prioritizing roads for removal or relocation. Key words connectivity; diffuse overland flow; risk assessment; runoff delivery

Sediment Dynamics and the Hydromorphology of Fluvial Systems (Proceedings of a symposium held in Dundee, UK, July 2006). IAHS Publ. 306, 2006.

Morphometric analysis of UK lake systems as a compliance tool for the European Water Framework Directive

JOHN S. ROWAN1, IAIN SOUTAR1 & GEOFF E. PHILLIPS2

1 Environmental Systems Research Group, Department of Geography, University of Dundee, Dundee DD1 4HN, [email protected] Environment Agency, National Ecology Technical Team, Reading, Berkshire RG1 8DQ, UK

Abstract The European Water Framework Directive 2000 (WFD) stipulates that surface water bodies, such as lakes, should achieve good ecological and chemical status (pollutant levels) by 2015. However, the extant environmental monitoring programmes of most member states have major deficiencies in terms of the baseline data required, thus potentially jeopardising the


compliance schedules of the WFD. Great Britain has over 40 000 lakes >1 ha, but bathymetric data are available for less than 2%. This paper presents a collation of available bathymetric data (622 sites) and demonstrates the utility of morphometric analysis to bridge the gap between surveyed and un-surveyed systems. Type-specific relations between mean (Dmv) and maximum (Dmax) water depths were developed for natural lakes (r2 values ranging from 0.87 to 0.99), as well as modified systems and impoundments (r2 values ranging from 0.74 to 0.99). Stepwise regression was also undertaken to predict Dmv and Dmax using only map-derived information (such as lake area, catchment area and shoreline length). The results varied markedly between “geological types”, with “medium alkalinity” (MA) lakes giving the highest coefficients of determination (R2 of 0.79 and 0.82, respectively). Predicting Dmv is important because it permits calculation of parameters such as the volume (V) (and hence residence time) and dynamic ratio (DR) which provides a measure of the likely extent of sediment re-suspension. This preliminary analysis has demonstrated the potential of the morphometric approach to generate valuable parameters from limited field investment and will provide a valuable stop-gap until the results of the WFD’s comprehensive monitoring programmes are realized.Key words hydromorphology; lake(s); morphometric analysis; Water Framework Directive


Flows that form: the hydromorphology of concave-bank bench formation in the Ovens River, Australia

G. J. VIETZ, M. J. STEWARDSON & B. L. FINLAYSON

eWater Cooperative Research Centre, School of Anthropology, Geography and Environmental Studies, The University of Melbourne, Melbourne, [email protected]

Abstract Ecological processes associated with in-channel benches have become a key focus of environmental flow studies in Australia. In this paper we present an initial investigation into the relationship between the morphology of mature benches and the flow regime responsible for their maintenance. We define benches as depositional features resulting from the vertical accretion of suspended sediment within a river channel. A two-dimensional hydrodynamic model (River2D) was used to represent the hydrodynamic conditions over a concave-bank bench on the Ovens River, southeast Australia, and deposited material was analysed. For stages higher than the bench surface elevation a large low-velocity and generally reverse-flow eddy is evident over the bench with velocities less than 0.2 m s-1 allowing for the deposition of silt and fine sand. Our results indicate that deposition on the bench is greatest during large in-channel flows and a depositional environment is still present at near-bankfull flows. These findings identify the importance of in-channel high-flow events for the maintenance of natural channel morphology.Key words concave bench; deposition; hydrodynamic; reverse flow; vertical accretion


The diversity of inundated areas in semiarid flood plain ecosystems

ORLA MURRAY, MARTIN THOMS & SCOTT RAYBURGWater Research Laboratory, University of Canberra, Australia Capital Territory 2601, [email protected]

Abstract Contemporary methods for managing flood plain ecosystems are biased towards temporal patterns of flow. Such approaches disregard the inherent spatial complexity associated with the flooding and drying of flood plain ecosystems and the influence this has on their productivity and biodiversity. This study investigates how the character of inundated patches changes through two flood events in the Narran Lakes ecosystem, Australia. A series of Landsat thematic mapper (TM) images were used to elicit patterns in inundated-patch character over time. Characteristics including patch number, size, shape and proximity to other patches were calculated for each image and subjected to multivariate statistical analyses. Strong positive relationships were observed between patch number; richness of patch area, shape and proximity and total surface area inundated. Hysteresis was also observed for the latter three relationships. This work highlights the importance of incorporating both spatial and temporal aspects of flood plain inundation in determining environmental water allocations for flood plain maintenance. Key words environmental water allocations; flood plain wetlands; fragmentation; landscape diversity; satellite remote sensing


Strategies for reducing sediment connectivity and land degradation in desertified areas using vegetation: the RECONDES project

PETER SANDERCOCK & JANET HOOKEDepartment of Geography, University of Portsmouth, Buckingham Building, Lion Terrace, Portsmouth PO1 3HE, [email protected] paper is written on behalf of the RECONDES project team

Abstract The aim of the EU funded project “RECONDES” is to bridge the gap between research and practice in relation to soil and land degradation and the onset of desertification in Mediterranean lands. The research is on the use of vegetation for restoration and mitigation of desertified areas and the major outcome will be guidelines on how vegetation may be used in the landscape to reduce erosion. Much of the erosion takes place in hot spots and specific locations related to zones of runoff concentration, often exacerbated by land- use practices and structures or lack of maintenance of traditional practices which previously prevented development of long runoff slopes. The major premise of the project is that vegetation can be used to reduce connectivity of flow and sediment transfers within the landscape. Within river channels the effect of vegetated reaches on flow and sediment flux are examined. Key words connectivity; EU project RECONDES; land degradation and desertification; Mediterranean; vegetation


Evaluating the effectiveness of the Illinois River Conservation Reserve Enhancement Program in reducing sediment delivery

MISGANAW DEMISSIE, LAURA KEEFER, JIM SLOWIKOWSKI & KIP STEVENSONCenter for Watershed Science, Illinois State Water Survey, 2204 Griffith Drive, Champaign,Illinois 61820, [email protected]

Abstract The ecology of the Illinois River, a tributary of the Mississippi River, was severely degraded for several decades due to sedimentation and water-quality problems. A joint federal/state program known as the Illinois River Conservation Reserve Enhancement Program (CREP) was initiated in 1998 to restore the river. One of the major goals of the program is to reduce sediment delivery to the river by 20 percent. To assess the program’s progress toward meeting that goal, the State of Illinois is developing a scientific process that includes data collection, modelling and evaluation. The baseline condition for sediment delivery was prepared based on available data collected in 1981–2000. Using that information as a baseline, it will be possible to assess and compare sediment delivery and sedimentation in the Illinois River valley for different periods after CREP implementation.Key words conservation reserve; enhancement; Illinois River; land use; monitoring; sediment delivery; sediment load; Illinois, USA


Unravelling the physical template of a terminal flood plain–wetland sediment storage system

SCOTT RAYBURG, MARTIN THOMS & ERIN LENONWater Research Laboratory, Institute of Applied Ecology, e-Water CRC, University of Canberra, Australian Capital Territories 2601, [email protected]

Abstract Flood plain–wetlands are hotspots of biological diversity and productivity, especially in semiarid environments and this is driven by water subsidies as well as the physical and chemical properties of flood plain–wetland soils. The purpose of this study is to examine surface soil characteristics in a complex, spatially diverse terminal flood plain–wetland to determine whether the surface soil characteristics follow a hydraulic gradient or reflect the more complex spatial mosaic. Surface soil samples (163) were collected from a regular grid with an average spacing of 1.8 km. Multivariate statistical analyses were performed to elicit spatial patterns in soil character and a series of surface maps of soil characteristics were derived to further explore spatial patterns within the flood plain-wetland complex. Results show surface soil characteristics to be spatially heterogeneous at multiple spatial scales and more complex than can be described by a series of hydraulic gradients.Key words flood history; Narran Lakes; semiarid; soil texture; surface soil


River sediment/pathogen interactions: importance for policy development on safe water practices

IAN G. DROPPO1, STEVEN N. LISS2, DECLAN WILLIAMS2 & GARY G. LEPPARD1

1 NWRI, Environment Canada, PO Box 5050, Burlington, Ontario L7R 4A6, Canada [email protected] Department of Chemistry & Biology, Ryerson University, 350 Victoria St, Toronto, Ontario M5B 2K3, Canada

Abstract The transport and fate of pathogenic pollutants are shown to be highly influenced by their strong relationship with suspended and bed sediment particles. As such, pathogen dynamics are strongly linked to the sediment dynamics of a system. Extracellular polymeric substances, although insignificant in terms of organic mass, are shown to be an integral part of the floc and contribute to the retention of microorganisms in the environment and may play an important role in the binding of pathogens. Implications of sediment pathogen interactions on policy development for safe water practices are discussed.Key words bed sediment; deposition; EPS; erosion; floc; pathogens; policy implications; suspended sediment; transport


Linking pattern and process: the effects of hydraulic conditions on cobble biofilm metabolism in an Australian upland stream

MICHAEL REID & MARTIN THOMS Cooperative Research Centre for Freshwater Ecology, University of Canberra, ACT 2601, [email protected]

Abstract Mesoscale variability in hydraulic conditions plays an important role in stream ecosystem structure and function. While the structural effects of variability have been widely tested, its influence on ecosystem processes is less well understood. This study examines the influence of spatial hydraulic variability on cobble biofilm metabolism in a regulated Australian upland stream. Primary production and respiration on stream cobbles forming the substrate in areas subject to three different flow conditions were measured using benthic chambers. Overall the cobble biofilms were found to be strongly autotrophic (P/R >> 1). Rates of respiration and, to a lesser extent, production were greatest where flow velocities and turbulence were low. Concentrations of chlorophyll a, pheophytin a and organic material were also highest in areas of lowest flow velocities. Hydraulic conditions did not affect P/R ratios. The degree of autotrophy is likely to reflect the effects of a recent fire in reducing shading and increasing nutrient influx. The observed spatial patterns can be partly explained by the greater accumulation of biomass in low flow velocity areas, but qualitative differences in biofilms are also likely to be important. Key words flow management; hydraulic variability; primary production; respiration; surface flow type


Combining biology and hydrology—questions from an integrated study of chalk streams


ROGER S. WOTTON1 & GERALDENE WHARTON2

1 Department of Biology, UCL, Darwin Building, Gower Street, London WC1E 6BT, [email protected] Department of Geography, Queen Mary, University of London, Mile End Road, London E1 4NS, UK

Abstract Combining biology and hydrology has allowed us to investigate the effects of plants and animals on the transport of sediments in chalk streams. In developing our integrated study we needed to understand the different use of terms and approaches used by the two disciplines. We present some of the questions that have arisen and that have wider application in all studies linking biology and hydrology, a process we must encourage if we are to understand the functioning of flowing water systems. Key words aggregates; biology; chalk streams; end users; flocs; hydrology; integrated studies; microbiology; models; particles


Reservoir sedimentation trends in Ohio, USA: sediment delivery and response to land-use change

WILLIAM H. RENWICK & ZACHARY D. ANDERECKDepartment of Geography, Miami University, Oxford, Ohio 45056, [email protected]

Abstract In Ohio, USA, a sufficiently large number of reservoir sediment surveys is available to characterize spatial and temporal patterns in sediment fluxes in a disturbed landscape. In this study we analyse 156 sediment surveys from 68 reservoirs, representing sedimentation rates in the latter 20th century. The study area includes two major physiographic regions: a glaciated low-relief till plain dominated by agricultural land use, and a mostly unglaciated dissected plateau with greater relief dominated by forest land use. Despite about 80% agricultural land use in the till plain, specific sedimentation rates are lower than in the plateau region. The agricultural region shows a significant negative relation between specific sediment yield and drainage area, while the upland does not. This is interpreted as indicating significant alluvial deposition associated with accelerated erosion in the agricultural region. The absence of such a relationship in the plateau area implies more efficient sediment delivery there. Comparison of sedimentation rates from the early part of the record (pre-1960) with those of the latter part shows that sedimentation rates are declining in the agricultural region, but not in the upland area, consistent with a reduction of agricultural erosion in the latter half of the 20th century. There is also a weak trend toward flattening in the specific sediment yield–drainage area relation. If confirmed this would imply that the channels in some areas are beginning to shift from net sediment sinks to a neutral condition, roughly a century after the time of maximum upland erosion.Key words reservoir sedimentation; sediment delivery


Dating of reservoir and pond deposits by the 137Cs technique to assess sediment production in small catchments of the Hilly Sichuan basin

and the Three Gorges Region, China

ZHANG XINBAO1,2, QI YONGQING1, HE XIUBIN1, WEN ANBANG1 & FU JIEXIONG1

1 Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041 China [email protected] 2 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China

Abstract There is a huge number of small reservoirs and ponds with quite high deposition rates in the Hilly Sichuan basin and Three Gorges Region, China. Ponds in four small catchments in Yanting and Nanchong of Sichuan Province and Kaixian of Chongqing were selected for this study. Incremental samples of sediment deposit profiles for 137Cs dating were collected from the four ponds to estimate the volumes deposited since 1963. By analysis of the topographic characteristics and the 137Cs depth distribution in rice fields it was concluded that no significant sediment accumulation occurs in the valley areas. The direct estimates of catchment erosion infer rates of 566–1869 t km-2 year-1. The main factors accounting for the severe erosion of these regions are topography, soil erodibility and bedrock bedding conditions.Key words 137Cs; Hilly Sichuan basin; Three Gorges Region; sediment yield; small catchments


The role of organic matter on the adsorption of mercury in sediments from Amazon lakes, Brazil

DANIEL MARCOS BONOTTO1, MARCELO VERGOTTI2 & ENE GLÓRIA DA SILVEIRA2 1 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] Departamento de Geografia, UNIR-Fundação Universidade Federal de Rondônia, Av. Presidente Dutra no. 2965, CEP 78900-500 Porto Velho, Rondônia, Brazil

Abstract Gold has been exploited intensively in the Brazilian Amazon during the past 20 years, and the elemental mercury (Hg) used in amalgamating the gold has caused abnormal Hg concentrations in waterways. Since 1986 particular attention has been given to the Madeira River because it is the largest tributary of the Amazon River and gold mining was officially allowed on a 350-km sector of the river. In this paper, samples of sediments from nine lakes located in the Madeira River basin, Rondônia State, Brazil, were analysed for mercury and organic matter. The average Hg content ranged between 33 and 157 ppb, which is about 8–40 times higher than the average value corresponding to 4.4 ppb for rocks occurring in the area (regional background). Significant correlation was found between the Hg content and organic matter in the sediments, indicating its importance on the retention of this heavy metal. Key words Amazon lakes; Madeira River basin; mercury; organic matter; physical weathering; sediments



Using geochemical stratigraphy to indicate post-fire sediment and nutrient fluxes into a water supply reservoir, Sydney, Australia

WILLIAM H. BLAKE1, PETER J. WALLBRINK2, STEFAN H. DOERR3, RICHARD A. SHAKESBY3, GEOFFREY S. HUMPHREYS4, PAULINE ENGLISH2 & SCOTT WILKINSON2

1 School of Geography, University of Plymouth, Drake Circus, Plymouth PL4 8AA, [email protected] CSIRO Land & Water, PO Box 1666, Australian Capital Territory 2601, Australia 3 Department of Geography, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK 4 Department of Physical Geography, Macquarie University, North Ryde, Sydney, New South Wales 2109, Australia

Abstract Wildfire can lead to increased fine-sediment (and associated nutrient) delivery to water bodies downstream of burnt terrain. Burnt soils in the drainage basin of Sydney’s principal water supply reservoir show enrichment in nutrient and trace element properties (Ca, Mg, P, K, Zn and Pb) in association with mineralization of organic matter. This work aims to explore the potential for using geochemical tracers to quantify the impact of severe wildfire on downstream sediment dynamics and further, to see if a useful record of changing river basin sediment dynamics is recorded in reservoir sediment. Whilst fire-induced changes in geochemistry appear to offer a useful means for discriminating surface sediment sources with respect to fire severity, comparison with the geochemical stratigraphy of the lake is hampered by variable sedimentation dynamics linked to water level fluctuation and overprinting of source signatures by process-related transformations. Further exploration of the factors affecting catchment source signatures and linkages within the system are required before the sedimentary record can be used to full advantage.Key words Australia; nutrients; reservoir; sediment; tracing; wildfire


Variation of suspended sediment transport in the Timah Tasoh Reservoir catchment, Perlis, Malaysia: human impacts and the role of tropical storms

A. RAHAMAN ZULLYADINI & ISMAIL WAN RUSLAN HydroGeomorphology Research Group, Section of Geography, School of Humanities, Universiti Sains Malaysia, 11800 Minden, Penang, [email protected]

Abstract In recent years, soil erosion, sediment transport and deterioration of water quality in many river systems in Malaysia have become major concerns. Headwater streams emanating from forested and agricultural lands supply much of the potable water in this country. The quality, quantity and timing of water from these headwater catchments are strongly influenced by human activities such as deforestation associated with land conversion for agricultural purposes. This study investigates the impact of human activities and the role of tropical storms on the


variation of sediment transported into the Timah Tasoh Reservoir, Perlis, Malaysia. The study period was two years, with water samples and gauging carried out bi-weekly and additional intensive sampling conducted during storm events. These samples were integrated with data from two continuous hourly transmitted water-level recording stations located at the major river input of the reservoir. Flow and suspended sediment rating curves were developed and used to estimate the discharge and suspended sediment load. Regression equations were used to estimate the discharge and suspended sediment loading at stations with limited and discontinuous data. The variation of suspended sediment load is significantly affected by the human activities and the rainfall and runoff in the catchment area.Key words human impact; Malaysia; sediment load; Timah Tasoh Reservoir


The use of 137Cs and 210Pbex to investigate sediment sources and overbank sedimentation rates in the Teesta River basin, Sikkim Himalaya, India

W. FROEHLICH1 & D. 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] Department of Geography University of Exeter, Exeter EX4 4RJ, UK

Abstract This paper presents results from an investigation of suspended sediment sources and overbank sedimentation rates within the Teesta River basin, India. Sediment source fingerprinting techniques were used to provide information on the primary sources of the suspended sediment exported from the mountain part of the basin. Erosion of areas disturbed by mass movement provided the major source of the suspended sediment load of the river and channel and gully erosion were also important sources. The 210Pbex, 226Ra and 137Cs depth distributions in sediment cores collected from flood plains within the Teesta River basin have been used to derive estimates of overbank sedimentation rates. The estimated sedimentation rates at these flood plain sites vary from 0.21 cm year-1 for the upper flood plain level at the site near Boogadong to 3.56 cm year-1 at the site near the confluence of the Teesta River with the Great Rangit River. Key words 137Cs; 210Pbex;

226Ra; flood plain; overbank sedimentation; sedimentation rate; sediment transfer; suspended sediment source; Teesta River


The infilling of a terminal flood plain–wetland complex

ROBERT COSSART, MARTIN THOMS & SCOTT RAYBURG Water Research Laboratory, Institute of Applied Ecology, e-Water Cooperative Research Centre, School of Resource, Environmental and Heritage Sciences, University of Canberra, Australian Capital Territory 2601, [email protected]


Abstract Flood plain–wetland complexes are mosaics of physical units and the sediments contained within these various units often display spatial and temporal complexity. This paper reconstructs the environmental history of a mosaic of geomorphic units within a large terminal flood plain–wetland complex in southeastern Australia in order to identify how the sediment character of the mosaic has changed through time. Sediment cores, up to 14 m in depth, were extracted from one flood plain and three lake units. Stratigraphy and multivariate analysis on these cores reveal a complex environmental history with sediment character highly variable in both time and space. All four geomorphic units—lake and flood plain—have undergone a convergent evolution from unique initial states. This study highlights how numerical methods, in association with standard sedimentological techniques, can assist in unravelling the environmental history of a temporally and spatially diverse landscape. Key words complexity; convergence; sedimentation; stratigraphy


Sediment budgets and sinks in the Brahmaputra basin and their agricultural and ecological impacts

U. C. SHARMA1 & VIKAS SHARMA2

1 Centre for Natural Resources Management, VPO Tarore, Jammu 181 133 J&K, India [email protected] S. K. University of Agricultural Sciences & Technology, Chatha, Jammu 180 009 J&K, India

Abstract A multiple regression equation, giving sediment deposition (Sd) in sinks was developed, viz. Sd = a[41.73 + 0.181 slope (%) of the basin + 0.0046 average rainfall (mm) – 0.387 clay (%) – 8.125 vegetation cover at 1 to 5 scale]. The values of coefficient a for rivers, tributaries, temporary water storages, valleys and lakes and reservoirs were 0.0765, 0.1431, 0.1098, 0.0499, 0.0965 and 0.0100, respectively. The mean annual deposition was 9.5, 48.9, 14.6, 28.3, 23.0 and 31.3 mm, respectively, in the above sinks. The degree of removal of suspended particles by deposition (S) in river flow can be determined by the equation, S = antilog(0.69897 + log(Sp/Vav)); where, Sp is the average particle size (mm) and Vav, is the average flow velocity (m3 s-1) of the river. The soil erosion has caused land degradation and ecological imbalance in the basin.Key words agricultural and ecological implications; Brahmaputra basin; floods; sediment budgets; sinks


Holocene sediment budgets of the Rhine Delta (The Netherlands): a record of changing sediment delivery

GILLES ERKENS, KIM M. COHEN, MARC J. P. GOUW, HANS MIDDELKOOP & WIM Z. HOEKDepartment of Physical Geography, Faculty of Geosciences, Utrecht University, PO Box 80.115, 3508 TC Utrecht, The Netherlands

[email protected]

Abstract Holocene sedimentation in the Rhine-Meuse Delta is facilitated by sea-level rise and tectonics, but most important is the result of the sediment flux received through rivers from the hinterland. The majority of Rhine and Meuse sediment entering the delta was trapped between the apex and coastal barrier, at least during the Middle and Late Holocene. It is not known how much sediment was delivered to the delta over longer periods of time (>100 years), or how delivery rates vary over millennial time scales. Increased amounts of sedimentation owing to human land-use change (on top of climatic variability) are expected, but so far it has not been possible to quantify that impact or to establish since when it has been significant. Based on a multitude of subsurface data (borehole database, complementary digital maps, radiocarbon dates), deposited volumes for successive 1000-year time slices spanning the Holocene have been calculated.Key words climate change; human impact; Rhine Delta; sediment flux; sediment volumes; subsurface data


Changing fluxes of sediments and salts as recorded in lower River Murray wetlands, Australia

PETER GELL1, JENNIE FLUIN1, JOHN TIBBY1, DEBORAH HAYNES2, SYEDA IFTEARA KHANUM1, BRENDAN WALSH1, GARY HANCOCK3, JENNIFER HARRISON4, ATUN ZAWADZKI4 & FIONA LITTLE2

1 Geographical & Environmental Studies, The University of Adelaide, South Australia 5005, [email protected] Earth & Environmental Science, The University of Adelaide, South Australia 5005, Australia3 CSIRO Land & Water, PO Box 1666, Australia Capital Territory 2601, Australia 4 ANSTO, PMB 1 Menai, New South Wales 2234, Australia

Abstract The River Murray basin, Australia’s largest, has been significantly impacted by changed flow regimes and increased fluxes of salts and sediments since settlement in the 1840s. The river’s flood plain hosts an array of cut-off meanders, levee lakes and basin depression lakes that archive historical changes. Pre-European sedimentation rates are typically approx . 0.1–1 mm year-1, while those in the period after European arrival are typically 10 to 30 fold greater. This increased sedimentation corresponds to a shift in wetland trophic state from submerged macrophytes in clear waters to phytoplankton-dominated, turbid systems. There is evidence for a decline in sedimentation in some natural wetlands after river regulation from the 1920s, but with the maintenance of the phytoplankton state. Fossil diatom assemblages reveal that, while some wetlands had saline episodes before settlement, others became saline after, and as early as the 1880s. The oxidation of sulphurous salts deposited after regulation has induced hyperacidity in a number of wetlands in recent years. While these wetlands are rightly perceived as being heavily impacted, other, once open water systems, that have infilled and now support rich macrophyte beds, are used as interpretive sites. The rate of filling, however, suggests that the lifespan of these wetlands is short. The rate of wetland loss through such increased infilling is unlikely to be matched by future scouring as regulation has eliminated middle order floods from the lower catchment. Key words diatoms; flood plain; phytoplankton; salinization; sedimentation; wetlands


Unravelling flood history using matrices in fluvial gravel deposits

LYNNE E. FROSTICK, BRENDAN MURPHY & RICHARD MIDDLETONDepartment of Geography, University of Hull, Hull HU6 7RX, [email protected]

Abstract Experiments carried out in a laboratory flume have shown that the infiltration of sands into gravels is largely controlled by flood magnitude and frequency. Three sets of experiments were used to simulate low flows, small floods and large floods and these showed that at low and moderate flows almost all sand stays close to the surface; however, during large flood events the surface framework particles are entrained, the bed dilates and material falls through the pore spaces and accumulates at the base of the bed. In addition, bed load transport is enhanced when gravels are mixed with sand and heavy and light minerals become separated. These results suggest that the distribution of matrices in gravels carries with it a signal linked to flood history which might be unravelled given careful research.Key words bed load; flood history; gravel bed; river deposits; sediment mixtures


The importance of temporal changes in gravel-stored fine sediment on habitat conditions in a salmon spawning stream.

ELLEN L. PETTICREW & JOHN F. REXGeography Program, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia V2N 4Z9, [email protected]; [email protected]

Abstract Sediment (<2 mm and <75 µm) was collected in a productive sockeye spawning stream in northern British Columbia, Canada, using infiltration gravel bags from the pre-spawn through to the post-spawning period of 2002. As much of the gravel-stored fine sediment (<75 µm) exists as larger, aggregated particles composed of inorganic and organic matter, their quantity, structure, composition and settling behaviour were assessed. The goal was to evaluate the temporal changes in the gravel-stored fine sediment in the context of: (a) fish activity (i.e. active spawning and die-off) and (b) inter-gravel oxygen concentrations which reflect the habitat quality. Infiltration rates of <2 mm sediment increased with stream discharge and fish redd construction. The finer (<75 µm) sediment exhibited lower infiltration rates during the peak of fish spawning activity indicating successful reduction of this sediment fraction. Inter-gravel oxygen concentration decreased 18% over the period of active spawning and salmon die-off, but recovery occurred later. Aggregate particle size and density changes were explained by the physical action of spawning fish and the inter-gravel microbial activity associated with increased high quality organic matter (fish decay products) which reduced inter-gravel oxygen concentrations.Key words aggregates; dissolved oxygen; fine sediment; flocculation; gravel beds; organic matter; redds; salmon habitat

Sediment Dynamics and the Hydromorphology of Fluvial Systems (Proceedings of a symposium held in Dundee,

UK, July 2006). IAHS Publ. 306, 2006, 442-449.

Pacific salmon and sediment flocculation: nutrient cycling and intergravel habitat quality

JOHN F. REX1 & ELLEN L. PETTICREW2

1 University of Northern British Columbia, Geography Department, 3333 University Way, Prince George, British Columbia V2N 4Z9, Canada [email protected] 2 University of Plymouth, School of Geography, Drake Circus, Plymouth, Devon PL4 8AA, UK

Abstract Salmon-derived sediment flocs form during post-spawning die-off when organic matter from salmon carcasses combines with fine inorganic suspended sediments. These flocs deliver salmon derived nutrients to the stream bed where they enter the stream’s trophic network. To assess the influence of these mixed origin sediments on salmon stream benthic habitat, a re-circulating flume was constructed and seeded with gravel of a similar size to that from regional natal salmon streams. Flume conditions for water depth, velocity, and suspended sediment were also similar to regional natal salmon streams. Following the addition of salmon organic matter, intergravel habitat quality was observed to change in three ways: (i) the proportion of silts (10–63 m) increased, (ii) the carbon to nitrogen ratio decreased, and (iii) the biological oxygen demand of sediments increased. These preliminary results provide direct evidence that salmon derived organic matter influences the composition of inorganic sediments in, and the habitat quality of, the streambed.Key words British Columbia; flocculation; intergravel habitat; nutrient cycling; Pacific salmon; sedimentation


Sediment storage and transfer in the Mekong: generalizations on a large river

AVIJIT GUPTA1, S. C. LIEW2 & ALICE W. C. HENG2

1 School of Geography, University of Leeds and Visiting Scientist, Centre for Remote Imaging, Sensing and Processing, National University of Singapore, [email protected] Centre for Remote Imaging, Sensing and Processing, National University of Singapore, Singapore 119260

Abstract Our knowledge regarding sediment transfer and storage by a large river is limited. The morphology of the Mekong River and the physiography of its basin restrict sediment storage to its channel, or very close to it, for 4000 km, due to limited overbank accommodation space. Only for the last 600 km does the river move laterally to deposit sediment. This paper reviews: (a) the nature of sediment storage in the upper and middle Mekong; (b) sediment deposition in a wide flood basin in its lower course; (c) transfer of flood sediment into Tonlé Sap Lake; and (d) the seasonal pattern of sediment collection, transfer and storage along the river and into the South China Sea. The discussion is based mainly on satellite imagery at various resolutions, hydrological information from the Mekong River Commission, and field visits. It is suggested that the sediment storage pattern and the volume stored in the Mekong can be extensively disturbed by anthropogenic environmental alteration, such as the ongoing series of dam construction in the upper reaches.Key words dam; Mekong; satellite imagery; sediment storage; sediment transfer


River flood plains as carbon sinks

D. E. WALLING, D. FANG, A. P. NICHOLAS & R. J. SWEET Department of Geography, University of Exeter, Exeter EX4 4RJ, [email protected]

Abstract There is increasing recognition that overbank sedimentation on river flood plains is likely to represent an important sink in the global carbon cycle, significantly reducing the land–ocean transport of POC. There have, however, been few detailed studies of carbon storage on river flood plains and little is currently known about the role of UK rivers in this component of the carbon cycle. This paper reports the findings of a study aimed at investigating carbon sequestration associated with overbank deposition on the flood plains of six rivers in southern England, embracing a range of catchment characteristics and hydrological conditions. A total of 46 shallow sediment cores were collected at representative sites along the flood plains of the six rivers. These cores were sectioned and analysed to determine the depth distribution of both organic carbon and the fallout radionuclide 137Cs. The 137Cs data were used to estimate rates of sedimentation, which could in turn be used to estimate carbon sequestration rates. The results demonstrate appreciable spatial variability in the organic carbon content of overbank sediment deposits, both between rivers and between individual sites along a flood plain. The average organic carbon content of the upper 24 cm of the overbank sediments from the individual rivers ranged between 2.17 and 5.07%. The estimates of carbon sequestration rate obtained for the flood plains of the individual rivers were characterized by mean values ranging between 69.2 and 114.3 g m-2 year-1. These results confirm that the flood plains of British rivers are significant carbon sinks. Key words carbon cycle; carbon sinks; carbon storage; flood plain deposition; river flood plains; sediment cores; sediment deposition


Investigating the remobilization of fine sediment stored on the channel bed of lowland permeable catchments in the UK

ADRIAN L. COLLINS* & DESMOND E. WALLINGDepartment of Geography, University of Exeter, Amory Building, Rennes Drive, Exeter, Devon EX4 4RJ, [email protected]

Abstract The bed of the main channel system represents an important store of fine sediment in lowland groundwater-fed catchments, in the UK, on account of the deposition promoted by their naturally subdued hydrological regimes, low channel gradients and the reduction of flows caused by water abstraction. Although a number of recent investigations have contributed to an improved understanding of the magnitude and spatio-temporal variability of fine sediment storage, much less is known about the role of remobilization of fine sediment from the channel bed in the suspended sediment fluxes from lowland permeable catchments. To address this shortcoming, the



authors report the use of a composite fingerprinting technique, incorporating uncertainty analysis, to investigate the magnitude and timing of the remobilization of fine sediment sequestered on the channel bed of three lowland permeable catchments in the UK. The findings are used to assess the relative contributions of three principal potential sediment sources to the sediment loads sampled at the catchment outlets, namely: fine sediment remobilized from the channel bed of the main stem; suspended sediment inputs from tributary sub-catchments; and sediment originating from channel banks along the main channel.Key words remobilization; sediment fingerprinting; u sediment storage; ncertainty analysis


The impact of changes in climate, upstream land use and flood plain topography on overbank deposition

IVO THONON, HANS MIDDELKOOP & MARCEL VAN DER PERK Centre for Geo-ecological Research (ICG), Department of Physical Geography, Universiteit Utrecht, PO Box 80115, 3508 TC Utrecht, The Netherlands [email protected]

Abstract Changes in climate, upstream land use, and flood plain topography may drastically affect the functioning of flood plains as sinks for sediments and associated contaminants. We estimated the impacts of such changes on overbank deposition rates and conveyance losses for two reaches of the lower River Rhine by a scenario study for the year 2050. In the climate change scenario, deposition rates increase by 13% compared to current deposition rates, but combined with land-use changes, the deposition rates decrease by 12%. Topographical changes considered in the flood plain rehabilitation scenario cause an increase of 6% in the deposition rates. Conveyance losses, currently 5–7%, increase by a considerable 18% under the scenario with all changes combined. Flood plains are therefore expected to increase in importance as sediment and contaminant sinks under future changes.Key words climate change; flood plains; heavy metals; land-use change; modelling; overbank deposition; river rehabilitation; River Rhine; sedimentation


A gradient or mosaic of patches? The textural character of inset-flood plain surfaces along a dryland river system

MARK SOUTHWELL & MARTIN THOMSWater Research Lab, Institute of Applied Ecology, University of Canberra,Australia Central Territory 2601, [email protected]

Abstract This paper investigated the textural character of surface sediments across a range of inset-flood plain surfaces on the Barwon Darling River, Australia. Surface sediments ranged in size from clay to coarse sand (–1 – <4.75) but varied in composition between different inset-flood plain surfaces. Multivariate entropy analysis detected five sediment classes based on the

grain size distributions of individual samples. River channel sediments were present in two of the entropy classes, whereas the different inset-flood plain surfaces were present in four or more of the identified entropy classes. A number of factors may be influencing the spatial distribution of sediment texture across the inset-flood plain surfaces including: (1) decreasing energy gradients with increasing elevation from the channel; (2) variable sediment supply conditions during flow events; and (3) local sediment inputs. The resulting patterns found in the study area demonstrate there to be a mosaic of sediment texture patches rather than a simple gradient of changing sediment texture with increasing distance from the channel. Keywords Barwon-Darling River System; entropy analysis; flood plain sediment patterns; grain-size distribution


The deposition and storage of sediment-associated phosphorus on the flood plains of two lowland groundwater fed catchments

DEBORAH BALLANTINE1, DESMOND E.WALLING1 & GRAHAM J. L. LEEKS2

1 Department of Geography, University of Exeter, Exeter EX4 4RJ, UK [email protected] Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB, UK

Abstract Overbank sedimentation can result in the accumulation of sediment-associated nutrients on flood plains. This contribution reports the findings of an investigation of sediment-associated phosphorus (P) fluxes within the catchments of the Rivers Frome and Piddle in Dorset, UK, aimed at quantifying deposition of sediment and P on their flood plains associated with individual flood events. Sediment and P deposition were documented using Astroturf synthetic grass mats. Fractionation of the P content of the sediment provided useful information for identifying P sources in the catchments. Depositional fluxes of total P documented for individual flood plain sites in the study ranged from 0.66 g m-2 year-1 to 19.94 g m-2 year-1. Comparison of the two rivers shows both contrasts in their sediment budgets and the location of P sources within the catchments. Key words conveyance losses; phosphorus; river flood plains; sediment deposition


Sediment phosphorus dynamics in tile-fed drainage ditches

D. R. SMITH1, E. A. WARNEMUENDE1, B. E. HAGGARD2 & C. HUANG1

1 USDA-ARS, National Soil Erosion Research Laboratory, 275 S. Russell St, West Lafayette, Indiana 47907, USA [email protected] University of Arkansas, Biological & Agricultural Engineering, 203 Engineering Hall, Fayetteville, Arizona 72701 USA

Abstract Stream sediments may regulate aqueous phase phosphorus (P) concentrations. The

objectives of this work were to study the equilibrium P concentrations between the aqueous phase and sediments in tile-fed drainage ditches. Sediments from three ditches in Indiana, USA, were sampled and evaluated as P sources or sinks. Sediments that potentially release P to aqueous solutions could be chemically amended to sequester labile P. Sediment deposition from episodic storm events could increase the P buffering capacity of drainage ditches. In fluvarium studies (initial concentration of 0.55 mM P), aqueous P concentrations after 120 h were 0.075 mM and 0.111 mM for pre-dredged and dredged sediments, respectively. Phosphorus release from sedi-ments to the aqueous solution was greater from the dredged sediments. These studies are expanding our understanding of the dynamic nature of P in agricultural ditches, and aiding in the development of ditch management practices to reduce downstream P transport.Key words artificial drainage networks; phosphorus; sediment dredging; water quality


A framework for predicting delivery of phosphorus from agricultural land using a decision-tree approach

RICHARD BRAZIER1, MICHAEL SCHÄRER2, LOUISE HEATHWAITE2, KEITH BEVEN2, PAUL SCHOLEFIELD2, PHIL HAYGARTH3, ROBIN HODGKINSON5, DES WALLING4 & PAUL WITHERS5

1 Dept. of Geography, University of Sheffield, Winter St, Sheffield S10 2TN, [email protected] Centre for Sustainable Water Management, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK3 Institute of Grassland and Environmental Research, North Wyke, Devon EX20 2SB, UK4 Dept. of Geography, Exeter University, Exeter, UK.5 ADAS Catchment Management Group, Hereford HR1 3PG, UK

Abstract Diagnostic models such as the P Indicators Tool have been used to predict the risk of P losses from different areas of agricultural land to watercourses. These models embody the source–mobilization–delivery–impact framework as a simple logical summary of process understanding. however, the assessment of P delivery has been neglected in the past. An alternative, decision-tree approach to predict the delivery of P to water bodies is presented here. The approach was developed as part of the DEFRA PEDAL project (http://www.lec.lancs.ac.uk/cswm/projects) and makes use of national coverage data held within a GIS at the 1 km2 scale, in combination with a “field toolkit” of measurements and qualitative observations. For all catchments, monitoring of total P loads in receiving waters has occurred over recent years enabling evaluation of the modelling and field toolkit approach. Key words decision tree; delivery; phosphorus; prediction


Nutrient and contaminant enrichment in rural areas of southwest Germany

MARTIN SCHWARZ & STEPHAN FUCHS Institute for Water and River Basin Management, Division of Aquatic Environmental Engineering, Universität Karlsruhe, Adenauerring 20b, D-76131 Karlsruhe, [email protected]

Abstract The input of particle-associated nutrients and pollutants from rural catchments accounts for up to 50% of the total load into surface water of the state of Baden-Württemberg, southwestern Germany. The enrichment ratios (ER) were identified as a weak parameter in the load calculation. The aim of the investigation is to provide ER for particulate-associated nutrient and six contaminants (total P and Cd, Cr, Cu, Ni, Pb, Zn) from the field. Four areas with representative soil characteristics in the 35 752 km2 study area were selected. In each area four rural catchments with flood retarding basins (FRB) serving as sediment traps were selected for further investigation. In this paper, the first results from the “Grombach” catchment area are presented. The investigations reveal that the eroded loess from the catchment area is completely transported and nearly no enrichment of phosphorus occurs (ER = 1.03). The analysed silt and clay fractions from the catchment area and the sediment from the FRB show phosphorus concentrations in comparable ranges. The phosphorus concentrations in the sediment are higher near the outlet and the ditch than at the inlet of the sedimentation reservoir.Key words enrichment ratio (ER); erosion; flood retarding basin (FRB); Germany; heavy metals; model; soil region; nutrients; phosphorus; sediment


Salinity and erosion: a preliminary investigation of soil erosion on a salinized hillslope

MEL NEAVE1 & SCOTT RAYBURG2

1 Division of Geography, School of Geosciences, Madsen Building (F09), University of Sydney, New South Wales 2006, [email protected] Cooperative Research Centre for Water, University of Canberra, Australian Capital Territory 2601, Australia

Abstract This stu1dy aims to determine whether increasing soil salinity levels promote higher rates of runoff induced erosion. Rainfall simulation experiments, with an average intensity of 75 mm h-1, were conducted on eight 1-m2 runoff plots in central New South Wales, Australia. A cross-design method was adopted using three soil salinity levels (low, medium and high) and two vegetation covers (<10% and >30%). Multiple regression analyses reveal that the sediment concentration of runoff is positively related to soil salinity levels and negatively related to vegetation cover (R2 = 0.688; p > F = 0.048), suggesting a causal link between soil salinity and sediment mobilization. The results of this study will provide useful information to land managers seeking to redress salinity issues in terrestrial and aquatic ecosystems. Key words electrical conductivity; hillslope erosion; rainfall simulation; runoff; salinization; soil erosion


Analysis of local scour downstream of bed sills: preliminary results of experimental work


DONATELLA TERMINIDipartimento di Ingegneria Idraulica ed Applicazioni Ambientali, Università di Palermo, Viale delle Scienze, I-90128 Palermo, Italy [email protected]

Abstract Bed sills are often used to limit bed degradation, to control bed erosion around bridge piers or downstream stilling basins of dams. In this paper, the local scour that takes place downstream of the bed sill, in addition to the general erosion process, is examined. The data collected during experimental work are used to analyse the applicability of the relationship found in the literature and to define the relation between the maximum scour depth and the flow rate. Key words bed sills; experimental analysis; fluvial hydraulics; scour


Comparison of numerical and experimental study of dam-break induced mudflow

SZU-HSIEN PENG1 & SU-CHIN CHEN2

1 Dept of Space Design, Chienkuo Technology University, Changhua City 500, [email protected] 2 Dept of Soil and Water Conservation, National Chung-Hsing University, Taichung 402, Taiwan

Abstract The purpose of this preliminary study is to model mudflow movement in an idealized dam-break configuration. One-dimensional motion of a shallow mud layer over a rigid inclined bed is considered. The resulting shallow water equations are solved by finite volumes using the HLL scheme. A Bingham fluid model is chosen to describe the mudflow rheology. The simulations are validated by comparison with flume experiments. Unsteady mudflow movement is found to be reasonably well captured by the model. In addition, a decoupled algorithm is also employed in the present paper to compute the aggradation and degradation of bed-level elevation for Newtonian fluid by using the Manning-Strickler formula and Exner’s relationship.Key words dam-break flow; finite volume method; HLL scheme; mudflow


MOSESS: a model for soil erosion prediction at small scales

EDUARDO E. DE FIGUEIREDO1 & HÉRBETE H. R. C. DAVI2

1 Water Resources Research Engineering Area, Department of Civil Engineering, Federal University of Campina Grande, PO Box 505 – 58109-970, Campina Grande – PB, [email protected] Superintendence of Infra-Structure, Federal University of Rio Grande do Norte, PO Box 1524 – 59072-970, Natal – RN, Brazil

Abstract In contrast to fully distributed physically-based models, event-oriented models do not consider antecedent conditions. Both types of models are in general distributed and applicable at small and large scales. However, at small scales the effects of storage within the hydrological


system is negligible and both types of model can perform similarly. This motivated the design of MOSESS, a simple soil erosion model, which simulates runoff and erosion processes at small scales. The model takes into account antecedent conditions, with the processes and basin features represented by physical parameters. Runoff is generated either by an excess of rainfall over infiltration capacity or by saturation of the soil top layer over time, and soil erosion by rainfall and runoff. Applications of the model to small areas in Sumé, located in the semi-arid Northeast of Brazil showed that the processes were reasonably well simulated. MOSESS demonstrated its suitability as a simple soil erosion model with results comparable to those obtained with other calibrated event-oriented models.Key words event-oriented model; overland flow; small-scale model; soil erosion


Predicting erosion patterns using a spatially distributed erosion model with spatially variable and uniform parameters

DIRK H. DE BOERDepartment of Geography, University of Saskatchewan, 9 Campus Drive, Saskatoon, Saskatchewan S7N 5A5, [email protected]

Abstract Distributed models are generally viewed as the best type of model for evaluating the erosional response of a drainage basin to changes in land use, climate, and other controlling factors. In many instances, however, information about the spatial variability of the model parameters is not available so that, even though the model is spatially explicit, parameters are treated as though they were uniform across the basin. The objective of this study was to compare the results of model runs with spatially variable parameters with those of model runs with uniform parameters. The model used is Cascade 6, a grid-based erosion model which requires data on elevation, saturated conductivity, surface roughness, and soil cohesion for each grid cell. The model was applied to the 45-ha Catsop basin located in the province of South-Limburg, The Netherlands. This loess-covered basin has a gently to moderately sloping topography, and land use is predominantly agricultural. The model is calibrated for peak discharge and sediment rating curve, and calibration is carried out separately with spatially variable and uniform runoff and erosion parameters. Model results indicate that erosion rates for individual grid cells modelled with variable parameters can be predicted from the erosion rate modelled with uniform parameters for grid cells with a drainage area from 1 to 1000 grid cells. Thus, the spatial pattern of erosion in the basin can be modelled over 85% of the basin area even in the absence of information about the spatial variability of the runoff and erosion parameters.Key words distributed model; erosion model; parameterization; sediment


Importance of watershed lag times in IUSG development

KAZIMIERZ BANASIK, MARIUSZ BARSZCZ & LESZEK HEJDUK

Warsaw Agricultural University, Department of Water Engineering and Environmental Recultivation, Sedimentation Laboratory, ul. Nowoursynowska 166, PL-02-787 Warsaw, [email protected]

Abstract Sedimentgraphs (graphs of suspended sediment load associated with hydrographs caused by rainfall) are essential for sediment yield assessments, for providing input data for prediction models of sediment deposition in reservoirs, for designing efficient sediment control structures, and for water quality predictions. An important part in the procedure of sedimentgraph prediction is the instantaneous unit sedimentgraph (IUSG) estimation. The IUSG used in this study has been developed by using the concepts of the instantaneous unit hydrograph (IUH) and the dimensionless sediment concentration distribution (DSCD). A procedure for estimating the sediment routing coefficient, which is a key parameter of the IUSG, based on measured rainfall–runoff-suspended sediment data (i.e. based on lag times), is applied. Also the relationships between IUSG and IUH characteristics (i.e. graph-peak values and times to peaks) are given. Field data from a small agricultural watershed in central Poland were used to demonstrate the relationship between lag times. The analysis shows that: (a) lag times are essential in estimating the parameters of IUSG; (b) a significant linear relationship exists between the lag time for hydrographs LAG and lag time of the sedimentgraphs LAGs; (c) the values of LAGs/LAG are for most cases smaller than 1 and decrease with the rainfall depth increase. Key words lag time; sedimentgraph; small watershed; suspended sediment; wash load


Impacts of land-use changes on sediment yields and water quality within the Nairobi River sub-basins, Kenya

SHADRACK MULEI KITHIIA1 & FRANCIS M. MUTUA2 1 Department of Geography and Environmental Studies, Postgraduate Programme in Hydrology, University of Nairobi, Box 30197, 00100 G.P.O. Nairobi, Kenya [email protected] Department of Meteorology, University of Nairobi, Box 30197, 00100 G.P.O. Nairobi, Kenya

Abstract Effects of land-use changes on sediment yields and water quality within the sub-basins of the Nairobi River were examined. The approach used assessed spatial variations in river runoff, sediment yields and water quality and involved collection of both water and sediment samples along the river courses. Most attention was given to suspended sediments within the Ngong, Nairobi and Mathare River sub-basins. The results indicated strong seasonal trends for both suspended sediment flux and water quality status. Suspended sediments loads for the Ngong River were 1733 t km-2 year-1, Nairobi River 6317 t km-2 year-1, and Mathare River to the tune of 2987 t km-2 year-1. Close relationships were found between total dissolved solids (TDS), conductivity, turbidity and colour. Generally, pollution levels varied with season and declined with distance downstream of Nairobi due to dilution effects and self-purification of the river waters during the wet season. Strategies to control increasing sediment yields and hence water quality degradation are suggested with a focus given to the Best Management Practices (BMPs) within the watershed and the country in general.Key words land-use activities; sediment yields; water quality status; water pollution and quality controls



Model investigations of the effects of land-use changes and forest damage on erosion in mountainous environments

PETER MOLNAR, PAOLO BURLANDO, JÖRG KIRSCH & ELKE HINZInstitute of Environmental Engineering, ETH Zürich, 8093 Zürich, Switzerland [email protected]

Abstract An event-based distributed rainfall–runoff–erosion model is applied to investigate runoff and sediment yield in a small mountainous catchment in central Switzerland under hypothetical scenarios of forest change. Scenarios such as progressive afforestation and deforestation, and forest damage caused by windstorms, are developed in order to analyse the changes in streamflow, spatial and temporal distributions of hillslope and channel erosion/deposition, and total sediment load. Uncertainties in the predictions related to the choice of the hillslope sediment transport formula are also illustrated. The prediction of the spatial distribution of erosion and deposition patterns is potentially very useful for identifying sediment sources, locating areas for field measurements, as well as a first indicator for hillslope erosion prevention measures.Key words erosion modelling; land-use changes; rainfall–runoff modelling


SWAT model for Integrated River Basin Management with application to the Mekong Basin

RIYADH AL-SOUFISäterinrinne 4(A1), Espoo, FIN-02600, [email protected]

Abstract The Soil and Water Assessment Tool, known as the SWAT model, is a GIS-based basin-scale model for simulating hydrological and water quality processes. It is a pseudo-physically based model that is capable of predicting long-term effects of land management. The model was applied to simulate rainfall–runoff process, streamflow pattern, soil erosion and sediment transport in the Lower Mekong River Basin. This paper reports the major findings of analysing the flow and sediment transport at major locations along the Mekong River and discusses the results from the first-cut preliminary analysis. In addition, the paper briefly describes the hydrology of the Mekong Basin in connection with the human impact on the basin’s health and provides a critical review on the role of integrative models for the implementation of the IWRM concept.Key words erosion; hydrology; IWRM; Mekong; modelling; sediment; SWAT


Modelling the impacts of climate variability on sediment transport

EILEEN CASHMAN1 & KENNETH POTTER2

1 Department of Environmental Resources Engineering, Humboldt State University, 1 Harpst Street, Arcata, California 95521, [email protected] Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Engineering Hall, 1415 Engineering Drive, Madison, Wisconsin 53706, USA

Abstract The detection and prediction of changes in long-term sediment yield under changing land-use practices in a watershed are very difficult due to the sources of variability in sediment transport. An approach is described to examine variability in sediment transport introduced by spatial and temporal variation in rainfall. This includes the use of a rainfall–runoff and erosion model and a space–time rainfall database. A key finding is that there is increased variability in the relationship between sediment discharge and flow when variability in rainfall is incorporated into the simulation. Scaling effects are exhibited by increasing variance in the sediment rating curves generated from increasing drainage areas. Antecedent sediment supply, conditions of overbank flow, and the temporal and spatial structure of rainfall are important factors that influence the variance seen in sediment yield data. Key words KINEROS; rainfall–runoff model; sediment transport; spatial variability


Effects of rainfall variability and land-use change on sediment yield simulated by SHETRAN

EDUARDO E. DE FIGUEIREDO1 & JAMES C. BATHURST2

1 Water Resources Research Engineering Area, Department of Civil Engineering, Federal University of Campina Grande, PO Box 505, 58109-970 Campina Grande – PB, [email protected] Water Resource Systems Research Laboratory, Department of Civil Engineering, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK

Abstract In the Cariri region in the semiarid Northeast of Brazil, precipitation varies considerably in space and time, and land use changes as a consequence of deforestation. The effects of these factors on basin responses are qualitatively known, but an assessment of the magnitude of the effects is still needed. In this paper, the physically based and spatially distributed model SHETRAN was parameterized in order to simulate the processes of runoff and sediment yield in various catchments with changes in the annual rainfall totals varying from 400 mm (dry), through 600 mm (normal) to 800 mm (wet), and percentage of basin area deforested from 10 to 90%. The results showed that, overall, peak discharges and volumes at basin areas from 100 m2 to 137 km2, and sediment yields for areas up to 11 km2, increased by 1.5 to 12-fold as annual rainfall changed from dry to wet and deforestation from 10 to 90%, while annual sediment yields for the largest area (137 km2) increased by 38 times as annual rainfall increased from dry to normal, then to wet.Key words deforestation; rainfall variability; soil erosion

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Sediment Dynamics and the Hydromorphology of Fluvial …hydrologie.org/redbooks/a306/P306 Description, contents, abstracts.doc · Web viewThere is evidence for a decline in sedimentation