Sediment Dynamics for

Key words loess hilly and gully region; warping dam; ¹³⁷Cs; sediment layers; sediment yields; erosive rainstorm events; dating

------------------------------------------------------------------------------------------------------------------------------------------------------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, 211-219.

The importance of sediment control for recovery of incised channels
W. D. ERSKINE¹, A. C. CHALMERS¹ & M. TOWNLEY-JONES²

1 Sustainable Use of Catchments and Coasts, School of Environmental and Life Sciences, University of Newcastle – Ourimbah Campus, PO Box 127, Ourimbah NSW 2258, Australia

[e-mail]

2 School of Mathematical & Physical Sciences, The University of Newcastle – Ourimbah Campus, PO Box 127, Ourimbah NSW 2258, Australia
Abstract Dairy Arm drains a 39.8 km² catchment in the Hunter Valley, Australia, and recently began recovery from post-1949 incision. Recovery involved cessation of upstream progressing incision, leaving a 400-m long upper intact alluvial zone. Post-1985 incision in the 5.5 km incised zone re-exposed buried large wood and eroded bank-side trees, forming log steps which are natural energy dissipators. Degradation in a small section of incised channel bed stranded remnant parts as the contemporary flood plain. Stoloniferous and rhizomatous grass invasion of the developing flood plain accelerated overbank deposition and stabilised river banks. The lower 5 km depositional zone has started to erode over most of its length. In the upper section, pools and riffles formed by degradation, and the bed is now narrower and deeper than at any time since incision started in 1949. A recent decrease in annual rainfall reduced the frequency of flood disturbance, allowing vegetation to survive.

Key words river recovery; bed degradation; pool-riffle sequence; clonal and rhizomatous grasses; vegetation invasion; statistical versus practical significance

------------------------------------------------------------------------------------------------------------------------------------------------------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, 220-223.

The influence of density fronts on sediment dynamics within river-to-sea estuarine transitional waters
ROBERT W. DUCK

School of Social and Environmental Sciences, University of Dundee, Dundee DD1 4HN, Scotland, UK

[e-mail]
Abstract The interaction of river-borne suspended and bedload sediments with marine-derived sediments is complicated by the sharply defined lateral and transverse water density gradients of frontal systems that characterise many estuaries worldwide. These features, often recognised at the water surface as linear bands of foam or flotsam, develop principally due to tidal intrusion, axial convergence, longitudinal shearing and flow separation. However, knowledge of the relationships of such features with bathymetry is still poorly developed. Not only do frontal systems impact upon intra-water column fine particulate transport by entrapment and compartmentalisation, they also exert a control on the distribution of bedforms and bottom sediment grain size distributions, thereby delimiting often closely juxtaposed, but differing bottom current velocity fields on the ebb and flood tidal phases. In consequence, fronts are now considered as “sieves” within the transitional river-to-sea, estuarine sediment transfer system; this perception has been reinforced by numerical study of lateral grain size sorting.

Key words estuaries; density fronts; sediment compartmentalisation; sediment partitioning

------------------------------------------------------------------------------------------------------------------------------------------------------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, 224-228.

Sedimentation in the riparian zone of the Three Gorges Reservoir, China
Yuhai Bao, Hongwei Nan, Xiubin He, Yi Long & Xinbao Zhang

Key Laboratory of Mountain Environment Evolvement and Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China

[e-mail]
Abstract Annual water levels in the Three Gorges Reservoir (TGR) fluctuate by approx. 30 m, which can influence the riparian zone. Such changes include soil stabilization or restoration, re-vegetation, landscape management and environmental sanitation. However, there is a lack of information on the rates, magnitude and variability of sedimentation processes in this riparian zone. A field monitoring programme was conducted along the middle reach of the TGR during 2007–2009. Fifteen monitoring transects were instrumented with columnar sediment traps and erosion pins. Mean sediment deposition rates were 5.8 cm year^-1 at the 145–150 m level and 2.3 cm year^-1 at the 150–175 m level. The mean sediment deposition rate was approx. 12 cm year^-1 at tributary inlets and shoals and a maximum of 18 cm year^-1 occurred at the 145–150 m level. Sedimentation processes in riparian areas along the TGR will likely have an impact on the ecology and long-term operation of the TGR.

Key words sedimentation; riparian zone; water level fluctuation; Three Gorges Reservoir

------------------------------------------------------------------------------------------------------------------------------------------------------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, 229-237.

Application of sediment studies to the management and planning of water resources in the Sydney region
Anna K. Sim, Wayne D. Erskine & Russell Drysdale

Environmental and Climate Change Research Group, University of Newcastle, Geology Building, University Drive, Callaghan, New South Wales 2308, Australia

[e-mail]
Abstract Multi-decadal periods of alternating wet and dry periods have been observed in instrumental rainfall and flood records of eastern Australia. These periods are critical for the management of water resources in large cities such as Sydney. High-magnitude rainfall events are the primary source of infill events for Sydney’s reservoirs. The occurrence of these rainfall events is linked with multi-decadal periods of high- and low-flood frequency, with an increase in average rainfall of 10–30% in periods of high flood frequency compared to those of low flood frequency. The instrumental record, however, is too brief to capture the full range of this variability. Sediment studies, focusing on changes in sediment deposition over time, have been used to investigate long-term hydrological variability. Discontinuous flood plains in the drowned river valley of the Hawkesbury–Nepean River act as sediment traps, preserving a record of flood events. Sediment cores collected from one of these flood plains have been analysed for particle size distribution, loss-on-ignition, magnetic susceptibility and density. These analyses, in conjunction with a chronology established through radiocarbon and optically stimulated luminescence (OSL) dating, allow a record of sedimentation over the last ~1000 years to be constructed. This provides a proxy flood record, which in turn has been used as a measure of hydrological variability in the region. The reconstructed flood record from the Hawkesbury–Nepean River will be used in long-term climate models, essential for the management and planning of water resources.

Key words multi-decadal hydrological variability; sediment cores; flood frequency; water resources

------------------------------------------------------------------------------------------------------------------------------------------------------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, 238-244.

Observations on flow hydraulics in a gauging station of a small stream with high suspended sediment load (Vallcebre, eastern Pyrenees)
Guillaume Nord, Montserrat Soler, Jérôme Latron & Francesc Gallart

Institute of Environmental Assessment and Water Research (IDÆA), CSIC, Sole i Sabaris s/n, 08028 Barcelona, Spain

[e-mail]
Abstract Water depth and sediment concentration have been measured with a good time resolution (every 2 min during flood events and every 20 min for the rest of the time) since 1994 at the gauging station of the Cal Rodó catchment (4.17 km²). Since October 2008, mean water velocity has been measured at the same resolution using an incoherent (or continuous) Doppler instrument mounted on the bottom of the gauging station. This study focuses on the impact of suspended sediment transport on water depth measurement and the effect of high loads of suspended sediment on flow hydraulics. We take into account the effect of suspended sediment concentration on the measurement of water depth by the hydrostatic pressure probe. We also examine the relationship between water depth and flow velocity and the effect of suspended sediment concentration on this relationship.

Key words suspended sediment; stream; flow velocity; water depth

------------------------------------------------------------------------------------------------------------------------------------------------------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, 245-250.

Assessing riverine sediment–pathogen dynamics: implications for the management of aquatic and human health risk
IAN G. DROPPO^1,2,3,4, KRISTEN KING², SANDRA M. TIRADO³,
ANDREW SOUSA⁴, GIDEON WOLFAARDT⁴, STEVEN N. LISS^3,4 &

LESLEY A. WARREN²

1 National Water Research Institute, Environment Canada, PO Box 5050, Burlington, Ontario L7R 4A6, Canada

[e-mail]

2 McMaster University, School of Geography and Earth Sciences, Hamilton, Ontario L8S 4K1, Canada

3 University of Guelph, School of Environmental Sciences, Guelph, Ontario N1G 2W1, Canada

4 Ryerson University, Department of Chemistry and Biology, Toronto, Ontario M5B 2K3, Canada
Abstract While it is established that sediment/floc can harbour a significant quantity of pathogens, the erosion, transport and deposition dynamics of the sediment-associated pathogens is not well understood in relation to ecosystem and human health impact. In this study, annular flume experiments were run with Pseudomonas spp. CTO7::gfp-2 inoculated sediment to assess the erosion, transport and fate of indicator organisms in river systems. Correlative microscopy was used to visually assess the microbial-floc relationship and a flow-cell/shear-cell was used to assess the strength of the indigenous E. coli microbe-floc association. Results indicate that suspended cohesive flocs are the dominant form of pathogen delivery to the sand bed. Significant correlations were found between the indicator organisms (CTO7-gfp and E. coli) suspended solid concentration and shear level. It is concluded that the bed sediment can represent a significant source of pathogenic organisms to the water column, with regulatory water samples not necessarily reflecting recent microbial contamination from terrestrial sources, but also a re-suspension of previously settled pathogens from the river bed. As such, sediment–pathogen dynamics should be considered when identifying source areas, determining aquatic and public health risk, and modelling pathogen transport in river systems.

Key words floc; bacteria; pathogen; erosion; transport; fate

------------------------------------------------------------------------------------------------------------------------------------------------------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, 251-257.

Salmon as biogeomorphic agents: temporal and spatial effects on sediment quantity and quality in a northern British Columbia spawning channel
ELLEN L. PETTICREW & SAM J. ALBERS

University of Northern British Columbia, Geography Program, 3333 University Way, Prince George,
British Columbia V2N 4Z9, Canada

[e-mail]
Abstract Pacific salmon have a large biogeomorphic impact on their natal streams. An opportunity to utilize a regulated salmon spawning channel in the summer of 2009 allowed a temporal and spatial evaluation of the biologic and geomorphic effects of salmon spawning on fine sediment infiltration into gravel bed streams. These salmon transfer biologically valuable marine-derived nutrients upstream to their natal habitats, while at the same time imparting energy to the streambed via their spawning activity, thereby modifying the geomorphic conditions. Fine sediment infiltration rates were used to monitor the physical activity of redd construction, and the biological effects of die-off on the gravel bed. Infiltration bags and piezometers were used to determine the mass of sediment deposited on and in the streambed, and the oxygen content of the gravel bed, respectively. Sedimentation increased during the period of active redd construction while the proportion of organic matter in the gravel-stored sediment increased following the instream decay of carcasses. Results suggest that the response seen over a small spatial scale may be the result of flocs forming in the water column and infiltrating into the streambed. A response to both changes in quantity and quality of sediment was observed as reductions in inter-gravel oxygen values. Further work on nutrient and sediment loads in both the water column and the gravel bed will allow a rigorous mass balance model.

Key words salmon; gravel bed; nutrients; fine sediment; storage; biogeomorphology; geomorphic agent; flocculation; marine-derived nutrients

------------------------------------------------------------------------------------------------------------------------------------------------------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, 258-263.

Sediment impacts on aquatic ecosystems of the Bukit Merah Reservoir, Perak, Malaysia
WAN RUSLAN ISMAIL¹, ZULLYADINI A. RAHAMAN¹,
SUMAYYAH AIMI MOHD NAJIB¹ & ZAINUDIN OTHMAN²

1 HydroGeomorphology Research Group, Section of Geography, School of Humanities, Universiti Sains Malaysia,
11800 Minden, Penang, Malaysia

[e-mail]

2 Department of Geography, School of Humanities and Social Sciences, Universiti Pendidikan Sultan Idris,
35900 Tanjong Malim, Perak, Malaysia
Abstract In recent decades interest in suspended sediment dynamics has increased. There are many issues related to high suspended sediment concentrations, such as reservoir sedimentation, channel and harbour silting, as well as the ecological and recreational impacts of sediment management. This paper describes a study of the input and output of sediment in the small Bukit Merah Reservoir (BMR) in Perak, Malaysia. The reservoir received inputs from four rivers totalling about 37 600 t year^-1. More than 90% of the sediment input (approx. 35 000 t) came from the Sg. Kurau River. The average lake sedimentation rates were 0.36 mm year^-1 (1995–2000) and 0.48 mm year^-1 (2000–2005). The average suspended sediment concentration in the lake was between 8.6 and 13.5 mg L^-1, while turbidity ranged between 5.8 and 64.1 NTU. The reservoir is slightly eutrophic, caused by the impact of sediment and nutrients on the receiving water body.

Key words sediment inputs; Sg. Kurau; turbidity; secchi depth; eutrophication; Bukit Merah Reservoir (BMR)

------------------------------------------------------------------------------------------------------------------------------------------------------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, 264-270.

Determination of the geochemical baseline for the East River basin, China
LINCOLN FOK & MERVYN R. PEART

Department of Geography, The University of Hong Kong, Pokfulam Road, Hong Kong

[e-mail]
Abstract Baseline information serves as a point of reference against which future natural or anthropogenic changes to geochemistry may be evaluated. It may also serve to identify controls, such as rock type, upon geochemistry and has other applications. In 2007–2009, active stream sediment samples from the East River in China were collected and analysed in an attempt to develop a geochemical baseline. Sample density is around 1 per 200 km², covering a total area of 27 600 km². Situated in southern China, the East River basin contains three large reservoirs that are of great importance to flood control, power generation, shipping, and water supply in the region. The watershed is well vegetated and woodlands occupy ~75% of the basin area. The geology is heterogeneous: sedimentary units of various ages have been intruded by igneous rocks. In 2007, the population living within the watershed was some 12 million. The concentration ranges of the elements are consistent with average crustal values. The spatial variation of the geochemistry reveals that it is affected by both natural and anthropogenic factors.

Key words geochemical baseline; spatial distribution; East River, China

------------------------------------------------------------------------------------------------------------------------------------------------------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, 273-281.

The use of instrumentally collected-composite samples to estimate the annual fluxes of suspended sediment and sediment-associated chemical constituents
Arthur J. Horowitz

US Geological Survey, Peachtree Business Center, 3039 Amwiler Road, Atlanta, Georgia 30360, USA

[e-mail]
Abstract Experience from a long-term water quantity and water quality monitoring network for Atlanta, Georgia, USA, has indicated that many of the problems associated with event based-sampling in small, “flashy” watersheds can be overcome through the use of instrumentally collected (autosamples) flow-weighted composite samples. The benefits of composite samples relative to discrete samples include: (1) the ability to sample a larger number of events during a year; (2) the collection of substantially larger suspended sediment (SS) masses for more accurate and representative chemical and/or physical analyses; and (3) the capability of using composite sample-derived SS and sediment-associated chemical data in conjunction with such variables as maximum event discharge (QMax) and total event water volume (VolTot) to construct rating curves for estimating the SS and sediment-associated chemical fluxes of unsampled events.

Key words autosamplers; storm sampling; suspended sediments; rating curves

------------------------------------------------------------------------------------------------------------------------------------------------------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, 282-290.

Long-term sediment transport and delivery of the largest distributary of the Mississippi River, the Atchafalaya, USA
Y. JUN XU

School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge,
Louisiana 70803, USA

[e-mail]
Abstract River engineering in the Mississippi-Atchafalaya River system and changing land use practices in the Upper Mississippi River Basin have reduced sediment loads and modified sediment distribution to the continental shelf of the northern Gulf of Mexico. Concurrently, the Louisiana Gulf coast has been subject to the highest rate of relative sea-level rise of any region in the United States. This study investigated suspended sediment transport and delivery from the Atchafalaya River, a 187-km-long river-swamp system that carries about 30% of the Mississippi River’s water into the Gulf of Mexico. The study modelled long-term (1975–2004) riverine sediment fluxes, assessed land area changes in the Atchafalaya Bay, and analysed the relationship between riverine sediment supply and the delta fan process. The study showed a sediment inflow of 6.4 × 10⁷ tonnes year^-1 and a sediment outflow of 5.8 × 10⁷ tonnes year^-1 in the Atchafalaya. Seasonally, sediment loads were highest in the spring and lowest in the late summer, corresponding to the river’s hydrologic conditions. For the past 30 years, the Atchafalaya retained 9% of the inflow sediment, which is considerably lower than the double-digit percentage rates of deposition reported for the period from the 1930s to the 1960s. Satellite image analyses found rapid land accretion in the Atchafalaya Bay during the past two decades. Much of the newly created land area was quickly vegetated, stabilizing the small delta lobes against sediment resuspension.

Key words suspended sediment; riverine sedimentation; sediment rating curve; coastal land accretion; Atchafalaya Bay; Mississippi-Atchafalaya River; Gulf of Mexico

------------------------------------------------------------------------------------------------------------------------------------------------------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, 291-299.