Marsh Accretion with Sea Level Rise Steve Crooks, Matt Brennan, Justin Vandever, Jeremy Lowe, PWA John Callaway, USF Diane Stralberg, PRBO RSM Science Workshop April 14, 2010

Sensitivity of bird habitat to sea level rise Long term habitat evolution and sustainability of restored habitats Quantification of carbon sequestration with sea level rise

Marsh Elevation Marsh elevation response to: initial bed elevation, suspended sediment concentration, organic material accumulation, rate of sea level rise, and subsidence and compaction

Marsh98 Based on mass balance calculations described by Krone (1987) Accretion rate depends on: availability of suspended sediment depth and period of inundation As marsh aggrades, frequency and duration of flooding decreases and accretion rate decreases.

Sedimentation in tidal wetlands

Mineral sedimentation model Vegetation colonization elevation

Natural Marshplain Elevation in 2100 (relative to rising tidal waters) Dry density of carbon: 500 kg m 3 Initial marsh elevation: MHHW Orr, Crooks and Williams 2003 Will Restored Tidal Marshes Be Sustainable? San Francisco Estuary and Watershed Science. Vol. 1, Issue 1 (2003), Article 5. Vegetation die-back

Restored Marshplain Elevation in 2100 (relative to rising tidal waters) Dry density of carbon: 500 kg m 3 Initial marsh elevation: -0.5m MHHW Orr, Crooks and Williams 2003 Will Restored Tidal Marshes Be Sustainable? San Francisco Estuary and Watershed Science. Vol. 1, Issue 1 (2003), Article 5. Vegetation die-back

Model Revisions Allows acceleration of rate of sea level rise NRC-I (0.5m rise) NRC-III (1.5m rise) Organic matter added directly to bed elevation

ASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team March 3, 2000 Richardson Bay Petaluma Estuary San Pablo Bay

Approach Bio-geomorphic units Sediment supply Organic accumulation Sea level rise 100 year time frame

Model Runs Initial Bed Elevation Colonization elevation (+1.3m MLLW) MHHW (+1.8m MLLW) Subtidal, minimal waves (-0.6m MLLW) SSC 25, 50, 100, 150, 300 mg/l Organic Matter 0, 1, 2, 3 mm/yr Rate of Sea Level Rise NRC-I, NRC-III

Low sediment availability Converts to mudflat SLR Scenario: NRC-III Suspended Sediment Conc: 25 mg/L Organic sedimentation rate: 1.0 mm/yr

Medium sediment availability Tracks colonization elevation SLR Scenario: NRC-III Suspended Sediment Conc: 150 mg/L Organic sedimentation rate: 1.0 mm/yr

High sediment availability Keeps pace with SLR SLR Scenario: NRC-III Suspended Sediment Conc: 300 mg/L Organic sedimentation rate: 1.0 mm/yr

High initial elevation has larger net change in elevation as less frequently inundated and receives less sediment. Higher organic accretion raises bed elevations and reduces inundation period and inorganic accretion rate.

25mg/l – unlikely to sustain marshes 50mg/l – sustain marshes only under most favorable conditions (high initial elevation and organic accumulation) mg/l – sustain marshes for particular combinations

Next Steps Influence of waves Compaction and subsidence Integration in SLAMM-type model