Sedimentshed Delineation(Update)

Chesapeake Bay Program Sediment Workgroup

April 27, 2006

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NSC Sediment Workgroup 2006 Workplan

• Action Item #3 – Define and delineate “sedimentsheds” (which

will include a continued effort to interpret sediment science as it relates to the watershed and Bay) in a report by December 2006

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Topics Discussed to Date

• Presentation or discussion on…– Overview of Watershed/Water Quality Model– Shoreline Erosion– State’s Water Quality Standards– ETM Analysis– FSS:VSS Analysis– Sedimentshed Concept (definition, purpose,

etc)

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Summary WQS Conference Call (3/20)

• Is there a difference in nearshore vs. main bay station clarity?– MD DNR will have nearshore samples for FSS/VSS

• Is decreased clarity from sediment?• Are clarity violations from intense isolated events

or short term, more frequent, events?• Should sedimentsheds be defined in zero SAV

acreage areas (No grow zones)?• Define processes that cause water clarity

impairments

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Sedimentshed Definition• Previous

– Sedimentshed - Area, including upland, nearshore and sub-aqueous, that contributes the sediment loads that directly influence water clarity in specific shallow water habitats.

• Proposed based on Dec 2006 task– Sedimentshed - Area, including upland, nearshore and sub-

aqueous, with similar predominant sediment transport processes that directly influence water clarity in specific shallow water habitats.

• The specific shallow water habitats are the areas, excluding SAV no grow zones, where Bay water clarity standards must be achieved and are specific to each Bay water quality segment

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Sediment Sources vs. Processes

• Upland– Terrestrial– Channel– Legacy

• Shoreline and Bay– Tidal erosion– Shallow water wave

resuspension– Deep water resuspension (least

important to SAV)– Resuspended primary producers

(dead) in the water column• Oceanic Input

• Upland– Watershed erosion– Channel corridor erosion– Storage and trapping

• Shoreline and Bay– Tidal erosion (nearshore and

fastland)– Shallow water wave

resuspension– Deep water resuspension – Estuarine turbidity maximum

• Oceanic transport

Sources Processes

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Sedimentshed Meeting Discussion

• April 11, 2006• All sediment workgroup members invited• Purpose: Working meeting to begin

defining sedimentsheds with available data

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Meeting Discussion (Cont)

• Sedimentshed – Policy vs. Science for defining sedimentshed boundaries

• Group to focus on what can be interpreted from the current state of the science only

• Sedimentshed boundaries defined using surrogates to bound a sediment transport process

• Scale of data will define the boundary and the boundary will define the process

• Interpretation of Chapters 5 and 6 of sediment processes report (Langland and Cronin, 2003)

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Distribution of Holocene Sediment in Chesapeake Bay

• Wayne L. Newell, Inga Clark, and Owen Bricker (2004)

• Interpretation of recent data

• May not apply to shallow waters

• Will contact authors for details

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Proposed Surrogates…

…for Sediment Transport Processes• FSS:VSS• ETM• Sea level rise

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FSS:VSSLead: CliffordData analysis: • Gradients correlate with

process or source boundaries defined in other reports

• Replot as % FSS• Review multiple maps

with various breaks (Consider contours)

• Include monitoring station location

• Also consider plotting Kd

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ETM

Lead: Halka/LanglandData analysis: Jasinski• Temporary sediment

trap through recirculation

• Agreed to include as bounding surrogate

• ETM defined based on SAV growing season

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Sea Level RiseLead: KupusnickSource: Titus and

Richman, 2001• Correlation with areas

vulnerable to sea level rise with FSS:VSS ratio

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Ocean Input

Lead: Langland• Summary from sediment processes report

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Summary of Surrogates

• Each surrogate has caveats • All can be confounded by other factors• Best information we have to begin defining spatial

boundary on processes• Scale of data will define the level of detail for the

boundary and the boundary will define the process• Identifies limited amount of Bay wide data for this

analysis

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Sedimentsheds – Combining the Data

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Shoreline Erosion

• Revised estimates• Unsure how to apply as surrogate to define

sediment process boundary• Direct input into WQ model

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Sedimentshed Report

• Outline– Introduction and purpose– Surrogates (1 –2 page explanation)

• ETM• FSS:VSS• Sea Level Rise• Oceanic input

– Summary map • Overlay of process boundaries

• Complete first draft by mid-May for presentation at June WQSC meeting

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Refinement of Boundaries

• Site specific data • What is available?

– Coring in the Bay and tributaries– ???

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STAC Workshop Update

• Purpose: Review of sedimentshed methodology• Two workshops proposed

– January 2007• Small, selected, workgroup • Focus on and review the first stage of the sedimentshed process• Defining sedimentsheds using data or surrogates for processes

(independent of model)– January 2008

• complete review of the sedimentshed methodology with inclusion of the new WQ model results

• Currently the model is the only tool available that can connect the entire system

• Recommend this workshop be open to everyone• Facilitated discussion and breakout sessions

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Suggested Topics for Future Meetings

• Evamaria Koch – “Beyond Light: Physical, Geological, and Geochemical Parameters as Possible SAV Habitat Requirements

• John Gray, Doug Moyer, USGS• ???