ΛTKINS. Applications of Regional Sediment Management Concepts in Texas Estuarine Restoration Projects. Riparian Workshop Fort Worth, October 17, 2012

Transcription

1 Juan C Moya, PhD., PG Coastal Planning and Restoration Applications of Regional Sediment Management Concepts in Texas Estuarine Restoration Projects Riparian Workshop Fort Worth, October 17, 2012

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3 West Galveston Bay Regional Sediment Management Plan 1. Develop a plan that uses the understanding of sediment dynamics including input, output, and circulation 2. Identify sediment sources needed for habitat and environmental protection, restoration, and conservation 3. Propose ideas to manage sediments using adaptive management approaches, taking advantage of the natural processes and sedimentary patterns 4. Support initiatives to reduce or mitigate coastal erosion, coastal storm damage, and costs of sediment management

4 Morphologic Units in WGB Chocolate Bayou GIWW Bastrop Bay Oyster Lake WGB Carancahua Reef N. Deer Island Drum Bay Christmas Bay Follets Island San Luis Pass Galveston Island Gulf of Mexico

5 Geologic Evolution and Sediment Distribution

6 North Pleistocene Clays Holocene Coastal Deposits South

7 Barrier Island Geologic Model Storms >Washover Deposits>Hydric Soils>Marshes

8 Holocene Geologic Evolution of West Galveston Bay & Galveston Island Source: Anderson, 2007.

9 WGB Barrier Island Model Clay: Tascosa Soil Series Clay Soils on Pleistocene Sandy Soils Barrier Island Clay Soils on Pleistocene Sandy Soils Barrier Island Sand: Karankawa Soil Series

10 WGB Coring Strategy

11 Submerged Sediments in WGB (White et al. 1985) Pleistocene-Holocene Boundary Cores Grab Samples Sampled Sediments in WGB

12 Sediment bars on Galveston Island Core WB-31 on Galveston Island

13 Paleo-Brazos River Muds Core WB-6 West Shorelines

14 Maximum spring tide flood flow for the San Luis Pass, Bolivar Roads, and West Galveston Bay (ADCIRC model).

15 Maximum spring tide ebb flow for the San Luis Pass, Bolivar Roads, and West Galveston Bay (ADCIRC model).

16 TxBLEND-2D Salinity Model (Matsumoto et al., 2005) Salinity Contours in ppt.

17 Circulation and shoreline retreat is mainly dominated by wind Average Summer Winds Average Winter Winds

18 Shoreline Retreat Rates (Gibeaut et. al., 2003)

19 Circulation Cells/Sedimentary Basins in WGB Chocolate Bayou Submerged Shorelines of North WGB WGB West Basin WGB East Basin Bays and Lakes Barrier Island Shoreface San Luis Pass Submerged Shorelines of Galveston Island

20 USACE Projects: Dredging files by reaches

21 Total Dredging on Federal Navigation Channels 32,453,125 cy GIWW 6,676,430 cy Chocolate Bayou Dredging occurs on areas exposed to the Bay (breaching PAs or at Chocolate Bayou) 39,129,555 cy sediments since 1943

22 Limited Data Area Volumes in Cubic Meters Volumes in Cubic Yards 1. San Luis Pass Flood Delta 1,500,000 1,962, West of West Basin 4,800,000 6,278,000 5a. Galveston Island West Basin 5a 660, ,247 5b. Galveston Island West Basin 5b 960,000 1,255,632 5c. Galveston Island West Basin 5c 840,000 1,098,678 6a. Galveston Island East Basin 6a 720, ,724 6b. Galveston Island East Basin 6b 1,800,000 2,354,000 6c. Galveston Island East Basin 6c 792,000 1,036, Central Portion of WGB West Basin 5,500,000 7,000,000 Total 17,572,000 22,789,281

23 San Luis Pass Flood Delta Growth Evolution Accretion Rates Suggested: 1974 Short-term: 100,000 cy/yr (Morang, 2006; CHE, 2007) 1930 Long-term: 5,000 cy/year (Wallace et al. 2010) BEG (2004)

24 Coastal Restoration in Galveston Island: Shoreline Protection-Dredging-Disposal of Sediments-Planting

25 Galveston Island Submerged Sediment Bars

26 N N Embayment created in Marshes since ~100 ft N

27 Anticipated deposition sites for sediment management along the shorelines of Galveston Island Wind Direction Wind Direction Wind Direction Wind Direction Sediment Sediment Transport Sedimentation Transport Modifier Delehite Cove Delehite Cove Delehite Cove Newly Naturally Created Habitat Area Delehite Cove

28 Proposed Concept Zone of Marsh Establishment: A dynamic zone based on energy/lee side interaction

29 Sediment Transport Processes Sedimentation Modifier Zone of Active Sediment Circulation/Transport Zone of Marsh Establishment (No Dredging Zone)

30 High Dependency on Dredging

31 Copano Bay NRCS-Texas General Land Office Shoreline Restoration 2011

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34 Building with Nature = Long Term Self Sustainable Projects

35 Recommendations A. No dredging on the lee side of energy or between peninsulas using the concept of the zone of potential marsh establishment as restoration criteria B. Reduce dependency on dredging building with Nature C. Include the hydrologic improvements as part of restoration practices D. Establish a zone of no-dredging on the top of the Bay shoreface E. Soils series are different - Karancawa soils (sandy) on Galveston Island - Tascosa soils (clay) on Pleistocene

36 Discussion :

37 Questions? Juan Moya Atkins Global