Event- to decadal-scale water level fluctuations across the Mississippi River Delta

Along the coast, water level variability is driven by complex interactions among river hydrology, tides, storms, waves, sea level rise, vegetation, and morphological change in addition to the increasing influence exerted by anthropogenic factors such as flood protection, dredging, shipping infrastructure, and subsurface fluid extraction, among others. The Mississippi River Delta (MRD) is a stunning example of the challenges facing future coasts due to extreme wetland loss, high rates of relative sea level rise, and increasing vulnerability to storm surge, all of which will alter patterns of water level variability across time and space. In this presentation, we explore the primary drivers of water level variability in the MRD from the scale of single storm events such as the passage of cold fronts to the decadal-scale impacts of global atmospheric phenomena and tides. We show that the highest rates of land loss over the last 80 years have been recorded when water levels exceeded the multi-decadal mean due to the global atmospheric oscillations. Spatial variability in inundation due to river flooding and the spatial heterogeneity in water level fluctuations resulting from storms are assessed using a decade of water level measurements at nearly 300 Coastal Reference Monitoring Stations across the coastal region of the MRD. The analysis reveals that spatial heterogeneity across the MRD coast produces a more variable response to frontal passage than previously understood. These results provide a benchmark for evaluating the future impacts of large-scale hydrological restoration and flood protection occurring throughout the MRD.