Coastal Geomorphologist
Spatiotemporal variation in Oregon salt marsh expansion and contraction
Co-Author: Robert A. Wheatcroft
Abstract: Spatiotemporal patterns of salt marsh lateral change vary along the Oregon coast, reflecting complex drivers of marsh morphodynamics. To identify potential factors influencing salt marsh expansion/contraction, time-series (~10 y resolution over ~80 y) of marsh edge position and area were measured from aerial imagery in five Oregon estuaries with variable morphologies, fluvial sediment supplies, relative sea level change, and vertical accretion rates. In estuaries where there exists room for marsh growth onto unvegetated tidal flats, net lateral expansion occurs when vertical accommodation space is filled and under relatively high sediment supplies. Moreover, results suggest that conditions promoting elevated sediment supply in the mid-20th century – intensive timber harvest coincident with increased precipitation during the wet phase of the Pacific Decadal Oscillation (PDO) – caused marsh expansion. In the late 20th century, rates of expansion have slowed, sometimes giving way to net contraction; conditions favoring slowed sediment supply – reduced timber harvest and improved logging methods combined with reduced precipitation/discharge during the dry phase of the PDO – are likely culprits. More recently, edges continued to contract possibly forecasting vulnerability under future accelerated sea level rise. In addition to providing rates of salt marsh expansion/contraction for an understudied portion of the US coastline, these results highlight the importance of considering current salt marsh trajectories in the context of past land use and time-varying hydroclimate.
Products:
Peck, E. K., & Wheatcroft, R. A. (2022). Spatiotemporal variation in Oregon salt marsh expansion and contraction. Estuarine, Coastal and Shelf Science, 273, 107908. https://doi.org/10.1016/j.ecss.2022.107908
Data: Peck, E. K., & Wheatcroft, R. A. (2021). Spatiotemporal variation in Oregon salt marsh expansion and contraction (GIS data). https://ir.library.oregonstate.edu/concern/datasets/w0892j79s
Related Conference Abstracts:
Pacific Estuarine Research Society 2022 Meeting (virtual presentation, March 2022) "Spatiotemporal variation in Oregon salt marsh expansion and contraction"
AGU Fall Meeting, San Francisco, CA (virtual presentation, December 2020) "Linking salt marsh lateral change with vertical accretion: Insights from the Oregon coast, USA"
Funding: Research was funded by Oregon Sea Grant [project # NA14OAR4170064; R/HBT-21-Wheatcroft]; and an NSF Research Traineeship fellowship [project # 1545188]