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Louisiana Coastal Area Modification of Davis Pond Study Overview

Governor’s Advisory Commission on Coastal Protection, Restoration and Conservation Mark R. Wingate, PE Chief – Projects and Restorations Branch April 4, 2012. Louisiana Coastal Area Modification of Davis Pond Study Overview . Purpose.

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Louisiana Coastal Area Modification of Davis Pond Study Overview

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  1. Governor’s Advisory Commission on Coastal Protection, Restoration and Conservation Mark R. Wingate, PE Chief – Projects and Restorations Branch April 4, 2012 Louisiana Coastal AreaModification of Davis PondStudy Overview

  2. Purpose • To update the Governor’s Advisory Commission on progress of the LCA Modification of Davis Pond feasibility study: • Planning Objectives and Constraints • Alternatives under consideration • Other factors to be considered • Timeline to completion

  3. Background • One of 15 critical projects authorized in WRDA 2007 “to sustain a larger coastal ecosystem that supports and protects the environment, economy, and culture of southern Louisiana” • WRDA language provided sequencing insight • Modification of Davis Pond (MDP) - Title VII, Sect 7006(e) – LCA “4” • LCA “4” FCSA Signed 5 June 2009 (includes MDP) • Next Step – TSP selection (13 April 2012) • Chief’s Report to be signed - 1 Nov 2013

  4. Planning Goals and Objectives Goal: Identify operational change that maximizes restoration outputs in the Barataria Basin Objectives: Over the 50 yr period of analysis: Objective 1: Decrease the rate of land loss, and where possible, increase wetland acreage Objective 2: Increase the geographic extent and distribution of Davis Pond freshwater, sediment, and nutrients throughout the study area

  5. Planning Constraints • Avoid or minimize negative impacts to T&E (Pallid Sturgeon) • Avoid or minimize adverse impacts to habitat • Maintain level of flood protection/no induced flooding • Avoid or minimize impacts to navigation • Avoid or minimize low dissolved oxygen and/or algal blooms • Assess only operational changes • Other factors to be considered

  6. Analytical Tools • H&H Modeling (TABS) – detailed history and forecast of hydrology • SAND Model - estimates sediment deposition rates • WVA - estimates restoration outputs • IWR - economic analysis on cost effectiveness • Trade-off Analysis - Socioeconomic Impacts, EFH

  7. Modeled Area DIVERSION STRUCTURE MYRTLE GROVE GRAND ISLE

  8. Alternatives Under Consideration

  9. Plan Formulation • Developed an initial array of 42 alternatives • Screened based on criteria • Final Array • 8 alternatives ranging from “no-action” to operating at maximum capacity throughout year

  10. Future Without Project:No Action MYRTLE GROVE -Maintain current operation of structure X X

  11. River Stage Dependent/Open Continuous:Alternative 18 • Maximum possible flow throughout year • -No Salinity target • -No Time constraints MYRTLE GROVE X X X X

  12. Maximize Sediment Load and Maximize Footprint:Alternative 41 • Maximum capacity operation during sediment peaks • Establish new salinity target during non-sediment peaks MYRTLE GROVE X X

  13. Major Flow Event (3 Year Cycle): Alternative 17 -Capture maximum sediment for year 1 during sediment peaks -For years 2 and 3, focus on establishing new salinity target -Repeat 3 year cycle MYRTLE GROVE X X

  14. Major Flow Event (5 Year Cycle):Alternative 40 -Capture maximum sediment from the river for year 1 during sediment peaks -For years 2, 3, 4, and 5, focus on establishing new salinity target -Repeat 5 year cycle MYRTLE GROVE X X

  15. Maximize Sediment Load With Time Constraint (Jan – Apr):Alternative 42a MYRTLE GROVE • -Maximize flow during high river conditions • Establish new salinity target for remainder of year X X

  16. Maximize Sediment Load With Time Constraint (Jan-Apr):Alternative 42b MYRTLE GROVE • -Maximize flow during high river conditions • Maintain existing salinity target for remainder of year X X

  17. Maintain New 5ppt Isohaline:Alternative 39 MYRTLE GROVE -Establish new annual salinity target X X

  18. Projected Wetlands in Acres • No Action: 45% reduction in landmass over 50 years • Alt 18: 43% reduction in landmass over 50 years • Approximately 10 square miles difference between Alt 18 and No Action • Only assesses operational changes of DP structure *Values Assume Intermediate Sea-Level Rise

  19. Wetland Value Assessment Results (Year 50) - AAHU (Average Annual Habitat Unit) – Increased Habitat Quality

  20. Other Factors to be Considered • Planning Aid Letter • Environmental effects (adverse and beneficial) • Social effects (adverse and beneficial) • Risks and uncertainties

  21. Milestone Schedule

  22. Questions?

  23. Backup Slides

  24. IWR Analysis Alt 39 Alt 40 Alt 41 In thousands Alt 42a Alt 42b Alt 17 Alt 18

  25. Final Array of 8 Alternatives

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