Patterns of sediment deposition in subsiding coastal salt marshes, Terrebonne Bay, Louisiana: The role of winter storms

High rates of wetland loss in the Mississippi deltaic plain have been attributed to a combination of insufficient marsh sedimentation and relative sea-level rise rates of over 1.2 cm yr−1. This study examines contemporary patterns of sediment delivery to the marsh surface by evaluating the contribution of individual marsh flooding events. Strong meteorological effects on water level in Terrebonne Bay often mask the usual microtidal fluctuations in water level and cause flood events to be of unpredictable frequency and duration. Sediment deposited on the marsh surface was collected weekly at two sites. Preliminary results allow the relative contributions of tidal and storm inundations to be calculated. Maximum sedimentation is associated with strong southerly winds both causing increased flooding and mobilizing sediment from open bay areas. Sediment deposition is limited by the availability of suspended sediment and the opportunity for its transport onto the marsh surface.