Physical Evolution of Restored Breached Levee Salt Marshes in the San Francisco Bay Estuary

摘要: Since 1972 over 940 ha (2,300 ac) of leveed former salt marsh sites around San Francisco Bay have been restored to tidal action, purposely or through natural processes. The evolution these can inform predictions rates marshplain and establishment channel systems. A review the history 15 re-flooded ranging in size from 18 220 (45 550 age 2 29 years indicates that vegetation with more than 50% cover was established at nine within 4 20 years. remaining six aged approximately continue be less vegetated. is consistent following simple conceptual model physical marshes subsided breached sites. Initially, deposition estuarine sediment builds up mudflats allow once elevations are high enough for survive. Sites initially lower frame take longer vegetate those higher. Three factors appear retard time establishment: limited suspended supply, erosion deposited muds by internally generated wind waves, restricted exchange. These affect significantly larger comparatively short colonization experienced earlier, smaller, and/or levee restorations may not necessarily replicable breaching on restoration now being planned. Our also formation channels greatly dependent whether how site filled before breaching. Filled intertidal (above 0.3 m below mean higher water) quickly but after several decades show little development channels.