Examination of the Impact of Recent LaTex Hurricanes on Shelf Geomorphology

摘要

Rapid response offshore field campaigns conducted immediately after recent large hurricanes to strike the northern Gulf Coast including Lili (2002), Ivan (2004), Katrina and Rita (2005), and Ike (2008) have been combined with monitoring data during the storms and pre-storm observational datasets to allow their shelf geomorphological impact to be assessed. The work of multiple investigators shows that, although there are unique aspects to each storm related to storm characteristics and the sedimentary character of the shelf section they traversed, several common sediment transport phenomenon can be recognized. Ebb surge transport associated with the seaward return of the storm surge has a major impact on the ultimate shelf depositional pattern observed after each event. Event layers tend to show a recognizable erosional-depositional couplet marked by a basal hiatal surface and normally graded bedding. Resuspension of sediments caused by currents above critical erosion stress occurring during storm maximum has been observed to take place in water depths up to 35-40 m (115-148 ft) in the northern Gulf. The presentation will also suggest a way forward in creating predictive-forecast models for coastal geomorphological changes caused by large tropical events.