Proceedings of the U.S. Geological Survey (USGS) Sediment Workshop,
February 4-7, 1997
SEDIMENT TRANSPORT AND GEOMORPHOLOGY ISSUES
IN THE WATER RESOURCES DIVISION
G.F. Koltun, M.N. Landers, K.M. Nolan, and R.S.
Information needs for sediment data are changing rapidly. Historically,
the Water Resources Division provided data and analyses regarding sediment
transport and geomorphology issues that dealt primarily with engineering
structures in the river environment. Indeed, these early sediment studies
contributed substantially to the reputation of the United States
Survey (USGS) as a leading agency for assessing the Nation's water
resources. Today, the most pressing sediment-related problems are
associated with environmental questions such as the transport and fate of
attached pollutants, effects of sediment on aquatic biota and their
habitat, and changes in sediment transport related to land use change. In
short, current sediment issues require that sediment studies now address
multiple objectives in water resources management. This change places new
demands on sediment transport and geomorphology studies in the USGS and on
traditional methods which served the organization so well in the past.
Present and future work in sediment transport and geomorphology in the
Water Resources Division is based on the following tenets:
Listed below are some current issues confronting the USGS and some
(listed with bullets) of on-going or recently completed projects that
address those issues:
- Sediment is the largest contaminant of surface water by weight and
volume and has been identified by the United States Environmental
Protection Agency as the number one problem threatening America's
- Understanding the fate of sediment-bound pollutants requires an
understanding of the transport and deposition of sediment.
- The physical system of a river provides the framework for
understanding the chemical and biological systems. Increasingly
sophisticated studies of the chemistry and ecology of river systems
place additional demands on our understanding of the physical system.
- Hazards such as debris flows, landslides, and channel changes
during floods continue to be a nationwide problem.
Predicting response to channel or watershed modification -- Channel and
(or) watershed modifications can be identified as the primary cause of
anthropogenic sediment issues in the United States. Specific problems
associated with this issue include prediction of the impacts of
urbanization, agricultural practices, and stream channelization or
Instream mining -- Current
concerning instream sand and gravel mining are the effects of extraction
method, and the amount and timing of extraction on channel
- Investigations of sediment response to land use are being
conducted by several National Water Quality Assessment (NAWQA) study units
across the country.
- The effects of urban land uses on stream-water
and geomorphology are being investigated in many studies in the
southeastern U.S., for example in the Upper Chattahoochee River Basin that
includes the metropolitan Atlanta area in Georgia (Faye and others,
- Investigations of agricultural land-use effects and the effectiveness of
best-management practices are underway in the delta region of Mississippi,
in the Beaver Creek watershed in Tennessee, and in two small watersheds in
- A study being conducted in Missouri examines the
present state of instability of Ozark streams resulting from long-term
land-use changes and their effects on the physical aquatic habitat
- Many stream channels in southeastern Nebraska were
dredged and straightened during the early 1900's. A recent USGS study
examined the impacts of these stream modifications (Wahl and Weiss,
- A study being conducted on the Cache River in Illinois examines channel
instabilities (thought to be related to channel modifications) that
endangers a federally-protected wetland.
Forest fires and floods -- Forest fires are known to play a role
in altering the hydrologic regime of an area. Increased flooding and
sediment transport is one common consequence. Although research funds are
sparse, interest remains in the issue of off-site impacts of forest
- A study in the Front Range of Colorado focuses on an area of rapid
growth where the maintenance and development of infrastructure requires
large volumes of three resources, aggregate (primarily stone, sand, and
gravel), water, and energy. The objective in this study is to provide the
public and decision makers with information about the location and
characteristics of land, natural aggregate, water, and energy resources.
- Sand from the Brazos River is being mined and used for construction
purposes in nearby Houston, Texas. The USGS is conducting a study to
evaluate the effects of instream sediment removal on channel erosion and
sediment delivery to the Gulf of Mexico where sand is needed to replenish
Flood plains -- Flood plains are of interest as a conveyor of
water and sediment and as a repository of sediment and associated
- Studies are being conducted in Bandelier National Monument, New Mexico,
Custer State Park, South Dakota, to examine the changes in sediment
discharge and resulting modifications to the channels following forest
- A forest fire and subsequent floods in the Buffalo Creek
Colorado, pointed to the vulnerability of the western portion of this
corridor. A study in this watershed is being conducted to examine the
frequency of such events, the importance of fires and subsequent floods in
mountain landscape evolution, and the problems such floods create
downstream in the urban infrastructure (e.g. Denver water supply
Regulated rivers -- Sedimentation problems on regulated rivers are considerably
different from natural rivers. Problems include: sedimentation in
reservoirs, channel effects downstream of dams, dam removal, and in-stream
flow requirements for maintenance of channels and fisheries. Reservoirs
can profoundly affect the geomorphology of streams that have a large
natural sediment load, as the reservoir traps sediment and releases clear
water. The resulting downstream geomorphic effects of clear water
from dams typically includes channel instability (as the channel and banks
are eroded to satisfy the sediment carrying capacity of the waters),
channel bed armoring, and alteration of habitat (Collier and others,
- The flood plain of the Clark Fork, Montana, is impacted by
fluvial deposition of fine-grained tailings derived from the
mining and smelting district. Objectives of a USGS study are to examine
the extent and interaction of the channel and contaminated flood plain,
to develop a physically based model for cut-bank erosion.
- Dendro-geomorphic methods are being used in the Kankakee River basin to
determine long-term sedimentation rates in the flood plains. and then
compare sedimentation rates in natural and channelized reaches.
Channel stability / biological impacts -- Channel stability has long been a
impact of channel stability on structures, such as bridges, located in or
near the channel. That focus has shifted somewhat in recent years to
include concern for biological communities living in or near the channel.
Examples of problems with biological implications are: predicting the size
of flushing flows for spawning sites and maintenance of backwater areas,
identifying the temporal changes in bedload transport for substrate
mobility, and analyzing bank stability for riparian environments.
- In the Black Canyon National Monument, a series of upstream dams has
eliminated wide seasonal discharge fluctuations resulting in decreased
channel cross-sectional areas, reduced frequency of gravel and cobble bar
reworking, accumulation of fine sediments on formerly coarse banks and
bars, and increased riparian vegetation encroachment. Changes in channel
dimensions and riparian vegetation communities are strongly linked in
environments and an ongoing study is detailing the interaction of flow and
vegetation along the channel banks (Auble and others, 1994).
- In the Green
River below Flaming Gorge Dam, Utah, habitat improvements for an
fishery are made by seasonal releases from the dam (Andrews, 1986). In a
recent USGS study (Andrews and Nelson, 1989) a 2-dimensional model was
in one critical habitat reach to study how the river adjusts its shape to
- A 1996 experimental flood in the Grand Canyon was done
to provide data needed to predict the movement of water and sediment
floodflows. Methods for predicting the movement of water and sediment had
previously been developed and applied by USGS and other scientists at
flows. Measurements at flood flows were needed to extend the usefulness
these methods and to provide model verification (Collier and others,
- The USGS is collecting data In the Elwha River basin of northwestern
Washington to assess how sediment stored in two reservoirs will be
if, or when, the dams are removed. Removal of these dams could allow a
return of an anadromous fishery in this river, but land managers need to
understand the possible downstream impacts on habitat and infrastructure
from alterations in the sediment transport (National Park Service,
Cost efficient methods -- The WRD collects basic sediment data that
interpretive studies conducted by WRD and other agencies. In 1996,
sediment data were collected approximately daily at 153 stations across
U.S. That number represents a decrease of about 30 percent in the number
daily sediment stations that were operated a decade ago. The reduction in
basic data collection has occurred despite the fact that many difficult
questions regarding sediment transport and deposition continue to be
One reason often given for the decline in basic data collection is the
- Scour around bridge foundations is the leading cause of failure among more than
487,000 bridges over water in the United States. Field-data collection and
research studies have been conducted in 37 states in recent years to
address the need for improved scour design techniques and more complete
descriptions of channel scour processes. The USGS has compiled nearly 400
measurements of local scour at bridge piers, most collected in the past
decade; and has evaluated stream geomorphology and potential channel scour
at hundreds of bridge sites for state departments of transportation.
Results of this work include an advanced understanding of scour processes,
extensive channel-scour data collected during floods, improved
instrumentation to collect scour data, and more reliable predictive
- Water rights form the basis of some of the channel
issues in the west. An example is an ongoing study of the Snake River in
Idaho where one objective is to determine streamflows necessary to
channel islands which are ecologically important habitats. Detailed
topographic surveys are utilized in a 2-dimensional hydraulic model to
predict velocity distributions around the islands at a variety of flows.
- The objective of a USGS project on the Missouri River from Buford, North
Dakota, to St. Louis, Missouri, is to determine whether off-channel
habitat areas will be sustainable or whether these habitat areas will
simply fill with sediment resulting in decreasing conveyance at high
and increasing the hazard of levee breaks. Such detailed examination of
sediment distribution in a reach uses a 2-dimensional model.
- The relationship between storm runoff, channel disturbance, and benthic
community abundance and structure was the focus of a study recently
completed in the Big Darby watershed in Ohio (Hambrook and other, 1996).
Sediment as a conveyor of
contaminants -- Evaluation of water-quality conditions and mass transfer
chemical constituents in the Nation's rivers are important parts of the
USGS programs. Fluvial sediment is possibly the continentŐs most
contaminant and the medium by which large amounts of toxic substances are
transported. The association between the transport of trace metals and
sediment is so strong that the seasonal and annual transport of most trace
metals can be estimated from sediment flux.
- A time series of optical back scattering data is being
used as a less-expensive surrogate for suspended-sediment concentrations
San Francisco Bay. These optical back scattering data are being collected
to better understand processes responsible for release and transport of
sediment in San Francisco Bay.
- The USGS program SEDCALC, which is used to
compute records of daily sediment discharge, is being upgraded to provide
new functionality and to provide a more friendly and efficient user
- A new sediment laboratory computer program is being developed
at the USGSŐs Cascades Volcano Observatory. This program promises to
improve the efficiency of laboratory operations.
contaminant transport is of concern within all four WRD regions.
Nutrients, metals, pesticides, organics, and (or) radionuclides bound to
sediments pose ecological and human health risks in watersheds throughout
the Country. Several active interpretive studies in the U.S. have the
determination of sediment and associated contaminant loads as a major
element. The objectives of these studies are varied and include such
as to (1) characterize the hydrogeology and water chemistry of watersheds,
(2) assess the trophic state of lakes, and (3) provide information on
to base stream restoration strategies.
Natural hazards -- Life-threatening hazards that result from the occurrence of rare events
remain an important focus of the USGS. The public relies on the USGS to
assess hazards before, during, and after they occur. Such hazards include
debris flows triggered by heavy rainfall or following volcanic eruptions,
landslides on slopes destabilized by road or building construction,
dam-break floods, surging glaciers, and earthquakes.
- A project is under way in
to assess the influence of vegetated filter strips on the transport of
sediment and nutrients to a stream.
- Detailed measurements of sediment and
water chemistry are being made in several Massachusetts lakes to help
assess their trophic state.
- The WRD has an ongoing investigation in the
southeast Region to develop and document the capabilities and procedures
required to investigate and delineate the concentration and partitioning
inorganics with sediments. One product of this project was the
of a part-per-billion protocol used by the USGS for contamination-free
collection and processing of whole water samples for the subsequent
determination of dissolved trace elements. Effective methods have also
been developed for the total trace element analysis of sediments
- The WRD, in partnership with Geologic Division, plans to study how
much sediment is stored in the active channel of the Boise River, Idaho.
These data will be used to develop a long-term assessment of storage and
release of contaminants.
- Investigations of water, energy, and
biogeochemical budgets are being conducted at the Luquillo Experimental
Forest, Puerto Rico, and at Panola Mountain, Georgia. The project at
Luquillo Experimental Forest is comparing chemical weathering, erosion,
mass wasting processes in two tropical rain forest watersheds in the two
dominant local rock types, volcaniclastic and quartz diorite. The project
at Panola Mountain is investigating processes that control the movement
solute composition of water along hydrologic pathways that produce
streamflow in a forested Piedmont watershed. See Couch and others (1996),
Faye and others (1980), and U.S. Department of Agriculture (1996) for
- California and Nevada WRD Districts continue to
collect data on sediment being supplied to Lake Tahoe by tributary
Nutrients adsorbed to sediment have been blamed for increasing biological
activity in the Lake, which in turn reduces lake clarity.
- A study to
characterize the physical, chemical, and biological processes that affect
metals in acid mine drainage was conducted in the upper Arkansas River.
That study identified colloidal-sized materials as a significant conveyor
of trace metals (Kimball and others, 1995). Detailed transport modeling
short reaches of the channel has been used to further characterize the
geochemistry (Broshears and others, 1996).
Coastal processes -- Erosion of
coastal areas and loss of adjacent wetlands are important management
issues. Accelerated coastal erosion results from both natural and
man-induced factors including: saltwater intrusion, subsidence, sea level
rise, wind-blown surges, upstream channel modification, mineral extraction
activities, navigation and drainage projects, and agricultural practices.
Information integral to the understanding of this erosion problem is the
movement and storage of suspended sediment in the coastal estuaries and
slow-moving rivers that border the coast.
- Landslide hazards
assessment is a component of ongoing investigations in Puerto Rico and
Alabama.The Federal Emergency Management Agency has asked WRD and the
Geologic Division to study landslides triggered by the January 1997 floods
in Idaho where landslides and debris flows closed some roads and dammed
- Documentation of the recovery of channel systems following
eruption of Mt. St. Helens in 1981 continues at the Cascade Volcano
Observatory (CVO). Personnel at CVO are also doing basic research on
debris flow behavior and assessing flood and debris-flow hazards
with other Cascade and Alaskan volcanoes
Wetlands interactions -- The
maintenance of wetlands and their role in trapping and removing sediment
and other contaminants are important water resource issues. Determination
of wetland sediment budgets is paramount to our ability to understand and
maintain wetland functions.
Current sediment issues, such as those
discussed above, suggest that much remains to be learned within the topic
areas of sediment and geomorphology. Consequently, there is continued
for high-quality sediment data of both a long-term and short-term nature.
In order to better address current (and future) sediment and geomorphology
issues, we must seek out improved methods of data collection and analysis
to meet the broader sampling and data requirements imposed by their
multidisciplinary nature. At the same time, we must pursue every
efficiency in order to gather necessary data and operate within the
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97, p. 1012-1023.
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the Green River, Utah, to variation in discharge, IN Ikeda, S., and
Parker, G. (eds), River Meandering: American Geophysical Union, Water
Resource Monograph 12, p. 463-485.
Auble, G.T., Friedman, J.M., and Scott, M.L., 1994, Relating riparian
vegetation to present and future streamflows: Ecological Applications, v.
4, n. 3, p. 544-554.
Broshears, R.E., Runkel, R.L., Kimball, B.A., Bencala, K.E., and McKnight,
D.M., 1996, Reactive solute transport in an acidic stream: Experimental pH
increase and simulation of controls on pH, aluminum, and iron:
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in Grand Canyon: Scientific American, January 1997, p. 82-89.
Collier, M., Webb, R.H., Schmidt J.C., 1996, Dams and Rivers - A primer on
the downstream effects of dams: U.S. Geological Survey Circular 1126
Couch, C.A., Hopkins, E.H., and Hardy, P.S., 1996, Influences of
environmental settings on aquatic ecosystems in the
Apalachicola-Chattahoochee-Flint River Basin: U.S. Geological Survey WRI
Faye, R.E., Carey, W.P., Stamer, J.K., and Kleckner, R.L., 1980, Erosion,
sediment discharge, and channel morphology in the Upper Chattahoochee
River Basin, Georgia: U.S. Geological Survey Professional Paper 1107
Hambrook, J.A., Koltun, G.F., Palcsak, B.B., and Tertuliani, J.S., 1996,
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Basin, Ohio: U.S. Geological Survey Water-Resources Investigation 96-4315,
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rev. ed., Lewis Publishers, ISBN 0-87371-499-7, 136p
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stream disturbance at the drainage-basin scale--an example from gravel-bed
streams of the Ozark Plateaus, Missouri: Costa, J.E., Miller, A.J.,
Potter, K.W., and Wilcock, P.R., eds., AGU Geophysical Monograph 89, The
Wolman Volume, p. 219-239
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USGS in Hydraulic Engineering Proceedings 1990 National Conference, San
Diego, Highway Division of ASCE, pp.1009-1014.
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on transport in a river receiving acid mine drainage, upper Arkansas
River, Colorado, USA: Applied Geochemistry, v. 10, p, 285-306
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riffle-pool scale in gravel-bed streams, Ozark Plateaus, Missouri and
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1987-1992: U.S. Geological Survey Circular 1126.
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Contributions from Other Federal Agencies
Contribution from the USGS