| Barrier islands along Louisiana's coast are shaped by interactions between tropical cyclones and rising sea level. In particular, the Chandeleur Islands, on the eastern flank of the Mississippi River Delta Plain, have become severely fragmented by tropical cyclones and periodically inundated by rising sea level over the last 100 years. In order to better understand and constrain the effects of these factors on the Chandeleur Islands, rates of accretion and mineral deposition, along with stratigraphic data on particle size in cores from these islands and nearby marshes in the mainland of the St. Bernard Delta, were compared to a history of tropical cyclones in the study region, and tide gauge data from regional long-running gauges. Accretion rate history found at two of the five study sites was similar to the history of tropical cyclones. Only at one of these study sites did the mineral sedimentation rate parallel the rate of accretion. The other three sites did not exhibit an analogous pattern between the history of tropical cyclones and the rates of accretion and mineral sedimentation. The second part this study investigated the effects of relative sea-level rise on rates of accretion and mineral sedimentation on these islands and nearby marshes in the mainland of the St. Bernard Delta. Interestingly, four of the five study sites exhibited a positive correlation between both accretion and mineral sedimentation rates and RSLR. Overall, results from this study suggest that rates of accretion and mineral sedimentation on the Chandeleur Islands and in the mainland of the St. Bernard Delta, were largely controlled by RSLR, rather that tropical cyclone impacts. |
