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