Sediment Dynamics for

Sediment yield in Europe: regional differences in scale dependence
MATTHIAS VANMAERCKE¹, JEAN POESEN¹, GERT VERSTRAETEN¹, WILLEM MAETENS¹, JORIS DE VENTE² & FARUK OCAKOGLU³

1 Physical and Regional Geography Research Group – K U Leuven, Celestijnenlaan 200E, 3001 Heverlee, Belgium

[e-mail]

2 Estación Experimental de Zonas Áridas, EEZA-CSIC, Desertification and Geoecology Department, Almeria, Spain

3 Eskişehir Osmangazi University, Department of Geological Engineering, Eskişehir, Turkey
Abstract Current understanding of the regional variation in sediment yield (SY) and its scale dependence is limited for Europe. Based on an extensive literature review, a SY-database was assembled to bridge this gap. Measured SY-data from 1794 different locations throughout Europe were collected, representing a minimum of 29 203 catchment-years of records and comprising a wide range of catchment areas (0.01 km² to 1 360 000 km²). Clear differences were observed between the temperate regions of Europe (low SY-values, i.e. <50 t km^-2 year^-1) and the Mediterranean and mountainous regions of Europe where SY-values are generally higher (i.e. >300 t km^-2 year^-1). Furthermore, for most temperate regions a negative relationship was found between catchment area and SY. For mountainous and Mediterranean regions, this was generally not the case. A comparison of catchment SY with rates of sheet and rill erosion also points to clear regional differences. Whereas soil erosion rates are generally higher than SY for temperate regions, this is not the case for the Mediterranean region. This indicates the importance of other erosion processes (i.e. landslides, riverbank erosion, and gullies). The results illustrate important regional differences in the scale dependence of SY and emphasize the need for an integrated modelling approach considering various types of sediment source and sink.

Key words sediment yield; database; Europe; erosion; scale-dependence; sheet and rill erosion

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 53-58.

Impacts of sediments yields and water quality on the Nairobi River basin ecosystem, Kenya
Shadrack Mulei KITHIIA

Postgraduate Programme in Hydrology, Department of Geography and Environmental Studies, University of Nairobi, PO Box 30197-00100, Nairobi

[e-mail]
Abstract This paper presents the results of a study on the effects and implications of sediment yields on water quality within the Nairobi River basin ecosystem. Sediments from water samples were obtained from the Ngong, Nairobi, and Mathare river sub-basins. The results indicate a seasonal variation/trend for suspended sediments in each basin, and a similar trend in water quality degradation. Annual suspended sediment flux estimates for the Ngong, Nairobi, and Mathare rivers are 1700, 6300 and 3000 tonnes, respectively. The results further indicate a close relationship between certain water quality parameters, such as total dissolved solids (TDS), conductivity, turbidity and colour, to increased water quality degradation, on a seasonal basis. Land-use changes per basin, including agricultural, residential, industrial and urban, were used to identify the most dominant type of land-use activity and its impact on sediment yields and water quality degradation. Pollution and pollutant levels varied with season and distance away from the city of Nairobi in the three sub-basins. The streams were found to be less chemically polluted away from the city due to dilution effects and self purification during the wet season. The results indicated that sediment yields had a significant effect on the Nairobi ecosystems in terms of water quality degradation. Strategies to control, and hence reduce water quality degradation, suggested as a result of this study, include removal of solid wastes from the river courses, protection of the river banks from construction activities, as well as continuous monitoring to check on illegal dumping of wastes into the river as some of the Best Management Practices (BMPs) within the watershed, and the country in general.

Keywords variability; quality; management; aquatic ecosystems; stream restoration

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 59-67.

The effects of soil conservation on sediment yield and sediment source dynamics in a catchment in southern Brazil
GUSTAVO H. MERTEN¹, JEAN P. G. MINELLA², MICHELE MORO¹, CLAMARION MAIER¹, ELEMAR A. CASSOL³, DESMOND E. WALLING⁴, ROBIN T. CLARKE¹ & JOSÉ MIGUEL REICHERT²

1 Federal University of Rio Grande do Sul, Hydraulic Research Institute, Av. Bento Gonçalves, 9500. Porto Alegre,
Zip Code 91501-970, Brazil

2 Federal University of Santa Maria, Soils Department, Av. Roraima, 1000, Santa Maria, Zip Code 97105-900, Brazil

[e-mail]

3 Federal University of Rio Grande do Sul, Soils Department, Av. Bento Gonçalves, 7712, Porto Alegre,
Zip Code 91501-970, Brazil

4 University of Exeter, School of Geography, Exeter EX4 4QJ, UK
Abstract This paper presents a synthesis of results from a hydrosedimentometric monitoring programme in a small rural catchment (1.19 km²) that has undergone significant changes in soil management, which have altered sediment yield and source dynamics. The study is based on repeated surveys of land management, rainfall, water discharge, and sediment yield, as well source tracing investigations undertaken over a period of seven years. During this period, the catchment has undergone a transformation in soil management. Erosion rates in the farmed areas have responded to these management changes, with an almost 75% reduction in sediment yield compared with pre-management conditions. The primary sediment sources in the catchment include cropped fields, unpaved roads, and natural channels. Sediment source dynamics demonstrate significant contrasts between the periods before and after the introduction of conservation practices.

Keywords soil conservation; sediment yield; catchment monitoring; tobacco cultivation; sediment source tracing

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 68-75.

Apportioning sediment sources in a grassland dominated agricultural catchment in the UK using a new tracing framework
ADRIAN L. COLLINS¹, YUSHENG ZHANG¹, DESMOND E. WALLING² & KEVIN BLACK³

1 Environment Group, ADAS, Woodthorne, Wergs Road, Wolverhampton WV6 8TQ, UK

[e-mail]

2 School of Geography, Archaeology and Earth Resources, University of Exeter, Amory Building, Rennes Drive,
Exeter EX4 4RJ, UK

3 Partrac Ltd., 141 St James Road, Glasgow G4 0LT, UK
Abstract A novel tracing framework combining conventional sediment source fingerprinting and a dual signature tracking method has recently been tested in a grassland catchment in Cumbria, northwest England, UK. The former component of the framework provided information on the relative importance of generic sediment sources characterised as pasture (75±1%) or arable (9±1%) surface soils, damaged road verges (6±1%), channel banks/subsurface sources (9±1%) and the local sewage treatment works (1±1%), whereas the latter component was used to apportion sediment loss from grass fields between poached gateways (1±1%) or cattle tracks (28±1%) and wider areas of general pugging and poaching damage (46±1%). Uncertainty and prior information are explicitly recognised by the novel source tracing framework.

Key words grassland; source fingerprinting; tracking; uncertainty; prior information

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 76-83.

Analysis of suspended sediment concentration and discharge relations to identify particle origins in small agricultural watersheds
A. Vongvixay^1,2,3, C. Grimaldi^1,2*, C. Gascuel-Odoux^1,2,
P. Laguionie³, M. Faucheux^1,2, N. Gilliet^1,2 & M. Mayet^1,2

1 INRA, UMR1069, Soil Agro and hydroSystem, F-35000 Rennes, France

2 Agrocampus Ouest, UMR1069, Soil Agro and hydroSystem, F-35000 Rennes, France

* Address for correspondence INRA, UMR1069, SAS, 65 rue de Saint-Brieuc, F-35042 Rennes cedex, France

[e-mail]

3 INSA, GCU, Génie Civil et Urbain, F-35000 Rennes, France
Abstract The relationship between suspended sediment concentration (SSC) and discharge often is highly variable in headwater streams, which highlights the temporal changes in particle origin and availability in small catchments. This paper analyses this variability to identify suspended sediment (SS) origins in two small agricultural catchments in northwestern France. Turbidity and discharge were monitored at high frequencies at the outlets. Annual and monthly SS fluxes were very different in the two streams. At the flood scale, various methods were tested to trace sediment origins and to quantify their specific fluxes: SSC-discharge pattern interpretation, SS flux modelling, temporal variations in specific turbidity (turbidity/ SSC ratio), or phosphorus content. The high SS fluxes in one stream mainly were due to the mobilisation of instream sediment or to bank erosion. SS fluxes in the other stream mainly were due to slope erosion caused by intensive farming; however, input to this stream was limited because of naturally-occurring tree-lined banks.

Key words suspended sediment; stream bank erosion; hysteresis; flood; turbidity; discharge; particle availability; modelling

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 84-92.

Sediment–nutrient dynamics in selected Indian mangrove ecosystems – land use and climate change implications
AL. Ramanathan¹, Rajesh Kumar Ranjan¹,
M. Bala Krishna Prasad², Rita Chauhan¹ & Gurmeet Singh¹

1 School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India

[e-mail]

2 Earth System Science Interdisciplinary Centre, University of Maryland, College Park, Maryland 20740, USA
Abstract The eastern coast of India harbours a number of mangrove forests, which are now under stress due to climate change-induced sea level rise; sea level is steadily increasing at a rate of 9–12 cm year^-1. Current projections for sea level rise are about 0.4–0.9 m; this will have a devastating effect on Indian mangroves. There is significant variability in local C, N and P chemistry, and the accumulation and export of these nutrients are due to changes in land use patterns and rising sea level. Seasonal variations control sediment-associated trace metals, organic C, total N, and total P, and reflect spatial and temporal differences in sedimentary organic production. Population dynamics of polysaline species have changed drastically due to varying inputs of autochthonous sediments from land and salt water inundation/intrusion, mainly at the seaward ends of the mangrove forests. The nutrient-rich sediments create a breeding and fishing ground for various ecologically and economically important species. In these mangroves, sediment-associated trace element concentrations are also increasing as a result of anthropogenic inputs, and influence the biogeochemistry of the ecosystems. An effort has also been made to assess the trace metal concentrations in the three east coast mangroves of India (Sundarbans, Bhitarkanika and Pichavaram) to define the drivers for variations in metal distribution.

Key words mangrove; metals; nutrients; climate change

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 93-98.

Sediment delivery and erosion processes in drained peatlands
Hannu Marttila, Simo Tammela, & Bjørn Kløve

University of Oulu, Water Resources and Environmental Engineering Laboratory, PO Box 4300,
90014 University of Oulu, Finland

[e-mail]
Abstract Sediment delivery and erosion processes have been studied in a number of peatland drainage areas and catchments in order to determine the effects of drainage on sediment and erosion dynamics and mechanics. This information is necessary for management of catchments where sediment poses a serious risk to water protection. Results from recent studies performed in peat mining, peatland forestry and disturbed headwater catchments in Finland are reviewed and potential sediment load management methods are discussed for drainage areas and headwater brooks. The issues especially covered are erosion of organic peat, sediment transport and methods to restore and reduce the impacts of peatland drainage in boreal headwaters.

Key words sediment transport; erosion; peatland drainage; organic and inorganic sediment; stream and catchment restoration; management; stream ecology

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 99-105.

Sediment and nutrient transport dynamics in an urban stormwater impoundment
CYNTHIA YU¹ & MICHEAL STONE²

1 School of Planning, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

2 Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

[e-mail]
Abstract Urban impoundments are water storage measures designed to reduce flooding and provide flow augmentation. Their ability to enhance water quality varies greatly from site to site, due to differences in the quality of runoff, climate, design characteristics and mode of operation. Water quality in urban impoundments and downstream environments is often negatively impacted due to the excessive accumulation of sediments and associated pollutants. To mitigate the adverse impacts of urban development and improper reservoir design on water quality, there have been an increasing number of rehabilitation and redesign efforts in North America to improve water quality. While these engineering projects often focus on modelling water quality and redesigning impoundments to improve water quality, few studies have evaluated the water quality performance of impoundments that have been redesigned to enhance water quality. In the present study, sediment and associated nutrient transport dynamics resulting from redesign of an urban impoundment (Columbia Lake, Ontario, Canada) were studied during both pre- (2003–2004) and post-redesign periods (2006–2007). Hydrometric and water quality data collected at the inlet and outlet of Columbia Lake were used to determine pre- and post-design total phosphorus (TP) and suspended sediment (SS) loads as well as changes in treatment performance resulting from impoundment redesign. Mean outflow pre-design TP concentrations decreased from 116  6 µg L^-1 to 44  3 µg L^-1 and mean SS concentrations decreased from 67  5 mg L^-1 to 16  0.8 mg L^-1 during the post-design period. The net internal P loading rate decreased significantly after the reservoir was reconfigured. Factors influencing the observed decrease in post-design TP and SS fluxes include the removal of lake-bottom sediment, reconfigured bathymetry and naturalization of the shoreline.

Keywords reservoir design; stormwater impoundment; phosphorus; suspended sediment; water quality; rehabilitation

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 106-112.

Characteristics of heavy metal pollution in highway runoff
DINGQIANG LI, MUNING ZHUO & HUAYANG GAN

Guangdong Institute of Eco-environment and Soil Sciences, No. 808, Tianyuan Road, Guangzhou 510650, China

[e-mail]
Abstract The rainfall–runoff flow rate, and heavy metal content (Cu, Zn, Pb, Cd, Ni, Cr) for highway runoff events were studied for three roads in Guangzhou, China. During the rainfall–runoff event, a distinct “first flush” of heavy metals was recorded. Their concentrations peaked at an early stage during rainfall and then decreased with the progression of the rainfall–runoff event. Heavy metal concentrations reached their lowest values when the runoff flow rate peaked, and then increased slightly again as the runoff flow rate decreased. Heavy metals in the runoff showed significant correlation with one another, as well as a clear correlation with the quantity of suspended solids in the runoff. Most heavy metals existed either as adsorbed to suspended solids or as free metallic particles. The degree of heavy metal pollution was found to be closely related to surrounding land use. Runoff from an urban road had the highest mean concentration of heavy metals per runoff event, whereas runoff from a suburban road and a road at the urban–suburban boundary had lower heavy metal concentrations, and were similar. Lead was identified as the main heavy metal pollutant in highway runoff.

Key words highway; rainfall; runoff; heavy metal pollution

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 113-120.

Sediment loads in the lower Jinshajiang of the Yangtze River: current status and potential impacts of the cascade dams
Lu Xixi¹, Zhang Shurong², Jiang Tong³ & Xiong Ming⁴

1 Department of Geography, National University of Singapore, Singapore 119260

[e-mail]

2College of Water Sciences, Beijing Normal University, China

3 National Climate Centre, China Meteorological Administration, Beijing, China

4 Bureau of Hydrology, Changjiang Water Resources Commission, Wuhan, China
Abstract Dam construction has changed natural sediment loads in rivers at the global, regional, and local scale. This study investigates the potential impacts of four proposed cascade dams on downstream sediment loads in the lower Jinshajiang in the upper Yangtze basin. The sediment trapping efficiency of the proposed dams was computed, and the amount of trapped sediment estimated. The changing trends in sediment loads since the 1950s in the study section (both main channel and main tributaries) are examined to understand the current status and likely future trends after completion of the dams. A sediment budget is constructed for various time periods in the river section.

Key words sediment load; dam; reservoir; the upper Yangtze River (Changjiang)

------------------------------------------------------------------------------------------------------------------------------------------------------Sediment Dynamics for a Changing Future (Proceedings of the ICCE symposium held at Warsaw University of Life Sciences - SGGW, Poland, 14–18 June 2010). IAHS Publ. 337, 2010, 121-126.

New methods for estimating annual and long-term suspended sediment loads from small tributaries to San Francisco Bay
MIKOLAJ LEWICKI¹ & LESTER McKEE²

1 Polish Geological Institute, Rakowiecka 4, 00-975 Warsaw, Poland

[e-mail]

2 San Francisco Estuary Institute, 7770 Pardee Lane, Oakland, California 94621, USA
Abstract Estimates of suspended sediment loads entering San Francisco Bay (California, USA) have been generated in the past by a number of researchers. Recently, it has been confirmed that the loads entering the Bay from the Central Valley are decreasing over time; as such, the loads from small local tributaries may constitute an increasing component of the overall Bay sediment budget. Previous estimates of suspended sediment loads entering San Francisco are outdated because of the wealth of new data, evolving land uses, and the availability of new methods of analysis. Our report presents updated estimates of suspended sediment loads entering San Francisco Bay from local tributaries. This information is essential for developing management strategies for many surface-reactive pollutants (e.g. certain trace metals and hydrophobic organic pollutants). In our study, we explore and evaluate hydrological, physical, and land-use characteristics of the San Francisco Bay watersheds to predict relationships between watershed sediment loads and geomorphic processes, and ultimately, to provide an updated estimate of regional suspended sediment loads from small tributaries. Based on this analysis, peak flow explained most of the variability in the sediment loads. Measured annual suspended sediment loads in Bay Area watersheds vary inter-annually by two to four orders of magnitude. Regionally, the new discharge- and land-use-based estimate of contemporary average annual suspended sediment loads entering the Bay is 1 300 000 t. This is equivalent to an average of 155 t km^-2. It is estimated that 35% of this load is associated with mostly urbanized watersheds.