GIS-Based Assessment of Submarine Mudflow Hazard Offshore of the Mississippi Delta, Gulf of Mexico

Documented changes in bathymetry and geologic features have been incorporated into a GIS-based approach to map hurricane-induced mudflow susceptibility on the seafloor offshore of the Mississippi Delta. Available bathymetric data were interpreted to delineate areas of relative sea-floor stability over the past century, areas of active mudflow transport, and areas of active mudflow lobe deposition, incorporating mapping by Coleman et al. (1982). Our research is designed to provide regionally-consistent hazard information for the siting and design of pipelines and structures using readily available datasets. Based on interpretation of available datasets for the Mississippi Delta region, and our results for a test area using post-Hurricane Ivan (pre-Hurricane Katrina) bathymetric data, mudflow transport within the Delta generally occurs within well-defined submarine channels or gullies, spreading out onto the seafloor in deeper water to form over-lapping lobes of thick, viscous silty clay. Semi-stable areas between the mudflow channels locally provide the least hazardous locations for siting of future production facilities and pipeline routing. The zone of overlapping mudflow lobes located downslope of the gullies is an area of recent deposition vulnerable to mudflow overruns from upslope mudflows.