Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Wu W., Feldpausch K.

Coastal wetlands are highly productive ecosystems that provide important ecosystem services and are threatened by extreme hydrological events. We evaluated how Bonnet Carré Spillway openings in Louisiana, US, affected vegetation productivity in coastal wetlands on the neighboring Mississippi Gulf Coast, US. Our study area is two estuarine systems that differ in their proximity to the Bonnet Carré Spillway, elevation, and salinity including Hancock County Marshes on the west, and Grand Bay National Estuarine Research Reserve (NERR) on the east in Mississippi. We collected above- and belowground biomass samples in 2020 and 2021, developed linear mixed-effects models to predict vegetation productivity based on spectral information of Landsat and Sentinel satellite images. We applied the models to hindcast vegetation productivity based on historical satellite images approximately during May and August of years with and without Bonnet Carré Spillway openings to assess the openings' impact on vegetation productivity. We found that as the frequency and duration of the Bonnet Carré Spillway openings increased, the peak green aboveground biomass decreased in both estuaries in the year when the spillway opened and was concentrated in the region that is closer in proximity to the Bonnet Carré Spillway. The research calls for development of flooding management strategies that could reduce the frequency and duration of Bonnet Carré Spillway openings.