Mitigating for coastal erosion and C loss in the Mississippi Delta; do river water diversion do more harm than good?

Abstract

<p>Sediment, nutrient deprivation and saltwater intrusion, among other factors, are driving widespread organic soil collapse and marsh loss in the Mississippi River Delta. Freshwater wetland diversions were designed to reintroduce Mississippi River water and sediment into the adjacent basins to manage salinity and mitigate land loss. However, there is concern that loading of excess nutrients from the Mississippi River into Barataria Basin wetlands can potentially lead to increased soil OM decomposition, less soil strength or increasing buoyancy and decreased belowground biomass. A baseline study was effected of a 3,145 km<sup>2</sup> area of wetlands and estuaries within Barataria Basin in 2007, in which the spatial variation in plant and soils were described at 140 stations before full scale diversion operations began in 2009. A subsequent spatial survey was conducted in 2018 after 11 years of diversion influence. By resampling the top 20 cm, separated into 0-10 cm and 10-20 cm layers, in 2018 provides an assessment of the status of those soils produced since 2007 and provides context for changing soil conditions. For the 2018 sampling, the soil </p>