Proceedings of the U.S. Geological Survey (USGS) Sediment Workshop,
February 4-7, 1997
SEDIMENT RESEARCH AND MONITORING ACTIVITIES ON THE
UPPER
MISSISSIPPI RIVER SYSTEM AS PART OF THE
LONG TERM RESEARCH AND
MONITORING PROGRAM.
Robert F. Gaugush and James T. Rogala,
Environmental
Management Technical Center,
Biological
Resources Division,
U.S. Geological Survey,
Onalaska, Wisconsin.
Hank DeHaan and Prasanna
Gowda
St. Mary's University,
Winona, Minnesota.
Introduction
The Long term Resource Monitoring Program (LTRMP) was authorized under the
Water Resources Development Act of 1986 (Public Law 99-662) and extended
under the Water Resources Act of 1990 (Public Law 101-640 as an element of
the U.S. Army Corps of Engineers' Environmental Management Program. The
LTRMP is being implemented by the Environmental Management Technical Center
(EMTC), a Biological Resources Division Science Center, in cooperation with
the Upper Mississippi River System (UMRS) states of Illinois, Iowa,
Minnesota, Missouri, and Wisconsin.
The UMRS encompasses the commercially navigable reaches of the Upper
Mississippi River, as well as the Illinois River and navigable reaches of
the Kaskaskia, Black, St. Croix, and Minnesota Rivers. Congress has
declared the UMRS to be both a nationally significant ecosystem and a
nationally significant commercial navigation system. The mission of the
LTRMP is to provide decision makers with information to maintain the UMRS
as a viable large river ecosystem given its multiple use character. The
long-term goals of the LTRMP are to understand the system, determine
resource trends and impacts, develop management alternatives, manage
information, and develop useful products.
Sediment Transport/Geomorphology Working Group
The EMTC sponsored the formation of a Sediment Transport-Geomorphology
Working Group that was tasked with developing a framework of activities to
be used to understand sediment transport processes and the changing
geomorphology of the UMRS. This working group consisted of a limited number
of recognized scientists from the Federal, state, and private sectors.
This working group identified nine major tasks to serve as guidance for
sediment and geomorphology related activities at the EMTC: (a) a literature
review; (b) identification, compilation and review of existing hydraulic,
sediment, and geomorphic data; (c) acquisition of floodplain elevation
data; (d) mapping the geomorphology of the UMRS floodplain; (e)
establishment of an expanded sediment monitoring network; (f) estimate
tributary sediment discharges; (g) investigate and quantify sediment
transport and distributional processes within the UMRS floodplain; (h)
determine backwater sediment budgets; and (i) synthesis and estimation of
the future configuration of the UMRS channels and floodplain.
In situ sediment characterization: methods development
The measurement of sediment type (described by particle size distribution,
bulk density, moisture content, and organic content) typically requires
extensive sediment sampling with coring devices or Ponar dredges. While
the sediment sampling may not require considerable field time, time
required to complete laboratory analyses makes large-scale studies
prohibitive. Determination of bottom dynamic conditions (or the prevailing
hydrodynamic conditions that lead to sediment erosion, transportation, or
accumulation) require continuous recording of flow velocities above the
lake bed and sediment resuspension for the period of interest. Again, the
logistical demands of such sampling prohibit studies aimed at
characterizing large areas for sediment type mapping. An in-situ sediment
penetrometer, originally developed in northern Europe and modified for use
in areas off the main channel of the Mississippi River, can be used to
characterize a wide range of sediment types and the prevailing hydrodynamic
conditions of an area.
Sediment distribution in UMRS pools
The in situ sediment penetrometer is being used to develop both local and
pool-scale sediment distribution coverages. The local or small-scale uses
involve the development of high resolution maps for both pre- and
post-construction sediments near habitat rehabilitation and enhancement
projects. Large-scale studies have been performed to support the
development of sediment distribution maps in Pools 4, 8, and 13. These
large-scale studies sacrifice detail or high spatial resolution for large
areal coverage (i.e., the entire pool). In FY 1996, sediment monitoring
using the penetrometer was made an addition to the monitoring performed by
the UMRS states as part of the LTRMP. This stratified random sampling
program will provide data on sediment distribution in five of the UMRS
pools. These sediment distribution coverages will be used as the link
between the driving forces that create the physical template of the river
system and the biological responses to that template.
An empirical model of sediment distribution in UMRS pools
One facet of multi-year study program involving man-made islands as a means
of habitat restoration has been directed at understanding the physical
changes in current velocity and sedimentation patterns that take place
after island construction. Sediment type characterization over a limited
portion of the lake bed in Lake Onalaska (Pool 7) was performed with an
in-situ sediment penetrometer and sediment cores. Results from the field
sampling program were analyzed using kriging and the geographic information
system (GIS), ARC/INFO. These results were combined with those from a
sophisticated hydrodynamic model, FastTABS, to extend the sediment mapping
to the entire lake bed. Using the model outputs of flow vectors (current
velocity and direction), the bathymetry of the pool, and the open-water
period (April through September) wind vectors (wind speed and direction),
sediment characteristics and average bottom dynamics can be expressed as a
function of current, depth, and wind fetch. This model has been tested and
verified using sediment distribution data for the Lake Onalaska portion of
Pool 7 and is currently being applied to Pool 8.
Sediment budgets for UMRS pools
The transport of sediment into and out of the navigation pools of the UMRS
must be quantified as a first step in predicting the long-term
configuration of the system. To address this issue, a cooperative effort
by the EMTC, the USGS/WRD, and the States of Illinois and Iowa was
initiated in FY 1994. This effort to develop pool-scale sediment budgets
for Pool 13 on the Mississippi River and La Grange Pool on the Illinois
will continue through FY 1997. The work associated with Pool 13 involves
monitoring two sites on the Mississippi River (above and below Pool 13) and
four tributaries to Pool 13 for discharge and suspended sediment
concentrations. In La Grange Pool, monitoring involves two sites on the
Illinois River (above and below La Grange Pool) and four tributaries to the
pool.
Backwater sedimentation rates in selected LTRMP pools
Net rates of sediment accumulation were measured as changes in bed
elevation along selected backwater transects from 1989 to 1996. The
average net rate of accumulation was found to be lower than previously
reported for the UMRS. Mean rates (cm/yr) for the transects surveyed were
0.29 for Pool 4, 0.12 for Pool 8, and 0.80 for Pool 13. Rates were highly
variable and all of the study pools had transects dominated by either net
erosion or net accumulation. Most transects exhibited areas of both
erosion and sedimentation. Bed elevation changes also displayed temporal
variability, particularly in response to the Flood of 1993.
Identification and compilation of sediment and geomorphological
data
The Sediment Transport/Geomorphology Working Group identified the need for
the EMTC to assume a curatorial role for data pertaining to
sediment-related processes and the changing geomorphology of the UMRS. Work
in this area was initiated in FY 1994 to identify sources of sediment,
sediment transport, and geomorphological data. These data reside in a
large number of disparate sources and forms among Federal and State
agencies and universities. Efforts continue to develop and maintain a
complete and coherent sediment and geomorphology database for the UMRS.
Relating non-point loadings to watershed features: a GIS-based
approach
Sediment loading from any tributary to the main channel of the Mississippi
River is highly dependent on the land cover, land use and morphometry of
its watershed. The tributaries of the UMRS drain watersheds that vary
greatly in size, geology, slope, soil type, and their sediment loads. This
research activity utilizes available suspended sediment and discharge data
from tributary streams with GIS technology to a) analyze relationships
between sediment loads and watershed characteristics and b) produce maps
that compare discharge and suspended sediment loading among tributaries.
Modeling agricultural non-point loadings
An investigation of the Maquoketa River (a tributary to Pool 13) watershed
using a spatial-process model is being conducted. The objectives of this
research are to (a) predict agricultural non-point source loadings such as
sediment and nutrients from an agriculturally predominant watershed in the
UMRS using an integrated spatial-process model; (b) use observed and
predicted runoff, sediment, and nutrient loadings for model evaluation; and
(c) use the model to evaluate potential water quality benefits associated
with the adoption of alternative management strategies on the watershed.
The spatial-process model consists of the ADAPT model, a field scale model
to predict hydrologic and water quality responses, a methodology for
developing a balanced continuous hydrograph and a routing mechanism. It
uses Landsat Thematic Mapper data, NRCS soil databases, published farming
system information, topographic data and historic climatic data in
conjunction with Arc/Info GIS software to delineate watershed and
hydrologic response unit features which are inputs to the model.
Adaptive Environmental Assessment Models
Under the auspices of the Upper Mississippi River Basin Association, the
EMTC is cooperating with other State and Federal agencies in the
development and testing of adaptive environmental assessment (AEA) models
of the UMRS. The AEA process involves the development of science-based
heuristic models to facilitate communication among scientists, resource
managers, and other concerned parties. These models are designed to be
exploratory tools and focus on dynamic complexity rather than on detail
complexity and precise predictions of future states. Two AEA models have
been produced and are in the process of being tested and refined. A river
system model, currently running for Pools 2 through 10, was designed to
track the flow of water and sediment on a daily timestep and provides a
basic accounting framework for the system. A two-dimensional pool model,
currently using Pool 8 as a test case, was designed to track water levels,
flow direction and velocity, sediment deposition and resuspension, the
expected vegetation response, and fish habitat responses.
Workshop Proceedings
Contributions from Other Federal Agencies
Contribution from the USGS