Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Elkhorn Slough Tidal Wetlands Project December 8, 2006 Agenda • Scope of work • Task integration • Framework for projecting geomorphic change Tidal Hydraulics Study (1992) Azevedo & BlohmPorter Enhancement Plans (1991-1995) Stanford 3D Modeling (ongoing) Strategic Planning (2004–2006) ESNERR Initiates the TWP Task A: Literature Review of Management Actions Task B: Develop Restoration Alternatives Task C, D, E, & F Technical Analyses Selection of Preferred Alternatives Task G: Develop Conceptual Designs Literature Review – California & Beyond Brown Marsh, SE Louisiana Essex marsh, SE coast of England Develop / Refine Restoration Concepts • Use the existing planning process • Refine alternatives proposed in RFP Modeling Team Agency Panel Strategic Planning Team Science Panel Peer Review Community Panel Working Group Working Group Previously Identified Concepts 2 4 3 1. No action 2. Restore historic tidal inlet 3. Reduce opening under Hwy1 4. Reduce Parsons Slough tidal prism Integrated Technical Analyses (Tasks C, D, E, & F) Task C Task D Task E Assess Inlet Stability Hydrodynamic Modeling Predict Future Morphology Task F Predict Future Habitat Quantitative Analyses Guided by Conceptual Models • Provides an ‘intellectual roadmap’ for understanding & predicting changes • Highlights ‘cause-and-effect’ pathways useful during alternative analysis • Directs inlet analysis, computer-based modeling, and geomorphic projections Natural Morphology of Elkhorn Slough Source: Elkhorn Slough Foundation 1854 USC&GS Survey Historical maps, photographs and surveys characterize the natural system Inlet Modifications at Elkhorn Slough • New ocean inlet • Armored jetties • Maintenance dredging Prediction of Future Morphology Step 1: Understand the Geomorphic System – Identify geomorphic units & sediment budget elements – Analyze how physical processes will change Step 2: Project Change – Predict change of each unit – Assess if sediment budget can accommodate cumulative effects Step 3: Integration with Other Tasks – Predicted morphology is bathymetry of modeling (Task D) – Planform map of units influences habitat (link Task F) Prediction of Future Morphology Use information generated by the Reserve and others Source: CSUMB Seafloor Mapping Lab Source: Elkhorn Slough Foundation Physical Changes Affect Habitat (Integration with Task E) Task C Task D Task E Assess Inlet Stability Hydrodynamic Modeling Predict Future Morphology 6 5 7 Task F Predict Future Habitat 5 Inlet closure affects exchange of nutrients, energy, … 6 Changing tidal & salinity regimes affect vegetation 7 Marsh plain elevation relative to tides controls hydroperiod Predicting Future Habitats (Task F) Develop 10% Designs & Costs (Task G) END 6/26/06 Elkhorn Slough Tidal Wetland Plan Undiked Tidal Marsh Areas - Likely Major Mechanisms of Tidal Habitat Loss and Changes Creation of Moss Landing Harbor Deeper estuarine mouth Groundwater overdraft (agricultural & urban dev.) Sea level rise Tectonic events ? ? ? Decreased marsh elevations Increased tidal volume, range, & velocities Increased tidal flooding (inundation) ? Loss of tidal marsh (interior) • Plants physically removed by sediment erosion on the marsh plain Loss of tidal marsh (edges) • Plants physically removed by bank erosion Erosion of channel & tidal creeks Extended tidal creek network Erosion of soft sediments from mudflats & marsh plain Decreased (organic) sediment production Loss of tidal marsh (interior) • Marsh elevation not keeping pace with water levels exceeding plants physiological constraints (drowning) • Plant death likely caused by anoxic soil conditions Plants more susceptible to disease, etc. Increased macroalgae abundance • Smothers plants • Reduced light availability ? ? ? Decreased root biomass ? ? ? Decreased (mineral) sediment & freshwater supply Elevated nutrient levels (agricultural & urban dev.) Diversion of the Salinas River (agricultural dev.) Extension of Applied Geomorphic Tools Deep Water Wave Power (10^9 ft-lb/ft/yr) 1000 Usuall_closed_M Closed Inlets Usuaily_closed_D Seasonally_closed_M Seasonally_closed_D 100 Never_closed_M Never_closed_D Occasionally_closed_M Occasionally_closed_D 10 Open Inlets 1 1 10 100 1000 Potential Tidal Prism (Million Cubic Feet) 10000 Wave Analysis for Inlet Sizing / Stability Transfer Coefficients wave period wave direction Monterey Bay Wave Data wave period wave direction wave direction wave period Inlet Wave Exposure • Nearshore wave conditions estimated from offshore data and transformation coefficients • Use nearshore power for inlet stability analysis Application at Bolinas Lagoon