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Proceedings of the U.S. Geological Survey (USGS) Sediment Workshop, February 4-7, 1997


By Bill Garrett, U.S. Army Corp of Engineers

Welcome. I am pleased to be here at the USGS SEDIMENT WORKSHOP addressing "Sedimentation Technologies and Research needs of the Corps of Engineers for Management of Natural Resources in the 21st Century." This is an opportunity in this era of constrained budgets for agency professionals to network and share information on recent accomplishments and progress in research and technical developments which further our understanding of sedimentation processes, and the impact of sediment on the environment.

I have personal experience in dealing with some fairly significant sedimentation problems. In the aftermath of the 1980 eruption of Mt. St. Helens. I was impressed with how quickly a natural disaster of this magnitude could affect much of the infrastructure that the Corps had built in that region. Sediment deposits from the initial eruption and the subsequent hydrologic events filled flood control channels placing local communities at risk, the Columbia River Navigation Channel was blocked by sediment, interrupting international shipping and trade, water quality and habitat was severely affected and remains so many years later. Mt. St. Helens happened very suddenly and the effects were very dramatic and obvious. Similar sedimentation processes are going on today, 24 hours every day, the results are just as certain, only less visible since the incremental rate of change is less noticeable.

The effects of sedimentation are significant and have significant physical as well as budgetary effects on the Corps ability to accomplish our many missions. Budgetary pressures will continue to increase in the future. More and more of our budget is being devoted to Operation and Maintenance and less to new construction. The more we spend on maintaining what we have constructed in the past, the less we have available for needed new investments in environmental and water resource projects. That is why development of tools, analytical techniques and equipment that will allow us to do a better job managing our natural and budgetary resources in the future is so important.

To give you a feel for the extent of the problem, let me share a few "gee-whiz" numbers with you. The Corps manages 11.7 million acres of land and 9.9 million surface acres of water behind 569 dams. We maintain over 12,000 miles of commercial navigation channels and 275 locks. We maintain over 627 shallow draft and 299 deep draft harbors. These commercial navigation projects contribute to the efficient movement of over $568 billion in 1994 in foreign trade. The Corps dredges over 280 million cubic yards of sediment every year. The Corps spends over $408M per year or 12% of our total Civil Works budget on maintenance dredging activities.

We have over 8500 miles of levees and manage over 383 major flood control projects resulting in over $17 B in flood damages prevented in 1994 alone.

So my message today is this, much has been accomplished in advancing the science of sedimentology, but much remains to be done. The Interagency Sedimentation Project (FISP) has served the needs of the participating Federal agencies well for the past +50 years. Standardization of equipment and procedures for collecting and analyzing sediment data has been most successful in the free and confident exchange of data and study results among the agencies and the other sectors that rely upon them for information.

More recently, changes in mission of some agencies, evolving public values, and more constrained budgets have resulted in a need to reevaluate the present program of the Federal Interagency Sedimentation Project and reorient its activities to be more responsive to the needs of the participating agencies.

The following are a few of the sediment issues, not in any particular order, confronting the Nation and the Corps of Engineers that we need to consider:

  1. Reservoir Storage Depletion Improvement to the reservoir sediment surveying techniques; lower costs, simpler, and faster techniques.

  2. Sediment Yield Develop accurate watershed yield techniques coupled with watershed land use changes.

  3. Environmental Concerns Sediment transported contamination, the need for continued refinement of the equipment to collect and analyze this data.

  4. More research effort in addressing "how" Hydraulic and Sediment Movements impact biologic habitat.

  5. Sediment Related Hazards Debris flows; landslides

  6. Operation and Mainstream Channel-natural or manmade for navigation and flood control, etc. Gradation/degradation must be predicted/measured accurately, bank erosion rates must be monitored. Improved techniques to determine bank erosion rates are needed. Development of simple bed load sampling techniques are needed.

  7. Geographic Changes Development of techniques to forecast long-term changes in river regimes.

  8. Database Management Data management is probably the number one problem today as was standardization of sampling equipment in the early 1930's. Based upon the above issues, the Corps has identified several items for which there are not presently adequate equipment and/or procedures to address the problems.

Those items are listed below:

  1. Continued development of equipment and methods for measuring suspended sediment concentrations.

  2. Equipment and methods for determining in-situ particle size analyses of suspended sediment.

  3. Equipment and methods for making in-situ measurements including density variation with depth, shear strength, gradation, and chemical composition of deposited sediment.

  4. Improved equipment and methods for core recovery from sediment deposits.

  5. Laboratory equipment and methods for measuring sediment shear strength.

  6. Improved techniques for measurement of bedload movement of large sandbed streams.

  7. Improved sampler for collecting bedload samples in coarse bed streams.

  8. Automatic continuous bedload sampler for coarse bed streams.

  9. Improved bed material sampler for coarse material particularly in deep water.

  10. Continue Refinement/ Development of samplers (suspended, bed material, bedload) which will not contaminate samples when looking for metals, organics, and volatiles.

  11. Continue development/refinement of equipment and methods for in-situ measurement of adsorbed salt or other contaminants.

  12. A reliable, simple, inexpensive scour meter is still needed to determine the depth of scour at piers and abutments during floods.

  13. Modeling and Design Guidance:

    1. Developing multi-dimensional numerical modeling of sediment processes, including deposition, erosion, and transport in rivers, estuaries and along the coast.

    2. Developing design guidance for multi-objective stable channels that accomplish flood control, navigation, habitat, recreation, water quality, and asethic purposes.

    3. Developing numerical sediment modeling methodologies to address the needs of optimization in operation and maintenance activities in navigation and flood control channels, especially related to dredging.

    4. Developing design guidance for low cost bank protection methods.

These are a few things that I see as needs to be addressed as we enter the 21st century. I am confident that we are up to the challenge.

Thanks for the opportunity to be here today. I wish you a productive and enjoyable workshop

Workshop Proceedings
Contributions from Other Federal Agencies
Contribution from the USGS