Sediment Challenges in the Tombigbee River Basin by dfhdhdhdhjr

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									Sediment Challenges in the
 Tombigbee River Basin

    Peter J. Grace, USACE
   William H. McAnally, MSU
          Purpose of Presentation:
               To Highlight -
• Some sediment issues in the Tombigbee River
  basin.
• Needs for data to address those challenges.
• Need for a regional sediment management
  approach.
• Opportunities for improved coordination between
  basin stakeholders.
The Tombigbee River Basin
       •   Tennessee, Mississippi and Alabama
       •   Tennessee-Tombigbee Waterway
       •   40% of flow to Mobile Bay
       •   40% of sediment supply to Mobile Bay?
       The Tenn-Tom Waterway
• A route to the Gulf of Mexico for the
  inland waterway system
• Connects the Tennessee River to
  Mobile Bay
• The Waterway:
   – aids inland navigation
   – stimulates economic development
   – provides outdoor recreational
      opportunities
   – enhances wildlife habitat
      Sedimentation Challenges
•   Tributary erosion and sediment supply.
•   Deposition in the river, waterway, and ports.
•   Dredging, dredged material placement, and beneficial uses.
•   Impacts on cultural preservation and environmental quality.
•   Downstream sediment supply effects.
                 Tributary Erosion
• Tributaries are experiencing bed and bank erosion, which contribute
  to excess sediment loads downstream.
   – Flood Control Projects (Big Brown, Donivan, Twenty-Mile, and
      Mantachie Creeks).
   – Old Tombigbee River and Town Creek.
   – Matubby Creek and James Creek
   – Buttahatchie River
   – Others
• Upstream erosion threatens landowners and infrastructure, reduces
  projects effectiveness.
• Sediment inflows to the river deposit in the waterway and ports and
  move to downstream areas.
Tombigbee River – East Fork Tributaries
Donivan Creek
Twenty-Mile Creek
Mantachie Creek
James Creek – Columbus Pool
                Other Issues – Mussel Habitat

•   Five Listed Species of Mussels

•   Requirement to Pass 70 cfs at
    Hwy 78-Fulton
Other Issues – Cultural Resources
    Dredging, Placement, and Beneficial Uses

•   Waterway Dredging: >800,000 cu
    yd/yr
•   Port Dredging: >30,000 cu yd/yr
•   Upland Disposal Areas (DA’s):
    Limited DA capacities, and critical
    space limitations in some areas.
•   Possible beneficial uses:
     – common fill material
     – concrete and asphalt
        aggregate
     – capping materials
     – commercially sold home
        improvement materials
     – marsh construction
     – beachfill material
     – armor unit construction
        materials
Sediment Management
            Downstream Sediment Supply

• Insufficient Sediment Supply
    – Wetlands losses
    – Beach erosion
• Excess Sediment Supply
    – Oyster reef & other habitat sedimentation
    – Port and channel dredging



Upper photo courtesy of Scott
Douglass, U. So. Ala.
             USACE Data and Resources

•   GIS capabilities at CESAM and TTWW Management Center (ARCGIS 9.1)
•   Types of data include: Geospatial data
                         Hydrographic surveys
                         Dredging and dredged disposal area information
                         Water surface elevations
                         Spillway discharge data
                         Precipitation
                         Limited water quality data
                         Habitat management information
                         Recreation information
•   2005 EPA water quality investigation of Aliceville Pool.
•   1991 East Fork sedimentation study.
•   Possible new effort related to Dredging Operations and Environmental
    Research (DOER) Program.
                   Data Needs

•   Land-Use data
•   Best Management Practices
•   Non-federal maintenance dredging information
•   Water quality data
•   Top of bank surveys
•   Aerial photographs
•   Historical information related to erosion and
    sedimentation
                   Summary

• Upstream sediment issues are known in part
  and are significant.
• Downstream sediment issues are known in part.
  Are they significant?
• Linkage between upstream and downstream
  issues exists, but is it understood?
• What kind of information will resolve the
  unknowns?
• Will regional management/collaboration address
  issues better?
Questions/Discussion

								
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