RAPID: Quantifying Wetland Root Structure, Strength, and Uprooting due to Hurricane Ida

Louisiana State University, Baton Rouge LA

Investigators

Abstract

Coastal wetlands are valuable ecosystems. They improve water quality, provide wildlife habitat and biodiversity, store organic carbon, and protect coastal communities from storms by dampening waves and reducing storm surge heights. Yet, severe storms are one of the most common natural drivers of coastal wetland loss. For coastal Louisiana, the combined impacts of Hurricanes Katrina and Rita (2005) and then Hurricanes Gustav and Ike (2008) converted nearly the area of New York City into open water. As a result, predicting wetland loss due to hurricanes is an important goal because of the significant consequences with respect to coastal populations. This RAPID award will allow timely field testing and core sampling to quantify wetland root strength and structure in the Barataria basin of coastal Louisiana, which experienced extreme land loss from Hurricane Ida. This information will help inform the scientific community and public on how the wetlands are eroded, what controls erosional resistance, why some hurricanes are more damaging than others, and what potential is for long-term recovery. Hurricane Ida made landfall on the southeastern Louisiana coast, bringing storm surge and waves of approximately 4.5 m above the normal water level that caused immense damage to the natural and built environment, specifically undermining the wetland root systems and removing much of the marsh platform. Current knowledge of the ability of the wetland platform to withstand hurricane-induced uprooting is limited, and the roles of wetland root structure, biomass volume, and strength need further research. The objective of this RAPID research is to collect perishable data of wetland uprooting, including (i) quantifying the micro-scale live biomass, necromass, root structure, pore structure, and sediment density using X-ray Computed Tomography (XCT) scans; (ii) measuring the macro-scale field strength of root systems using cone penetrometer tests (CPTs); and (iii) assessing the resilience of wetland vegetation and root systems to recover from a disturbance. This award will develop new knowledge concerning how the wetland platform withstands storm surge and waves, how these systems could evolve over space and time (particularly in the face of sea level rise, restoration activities, and recovery after an extreme event), and how these changes could alter their ability to protect the coastline from further damage. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.