GEOENVIRONMENTAL MAPPING IN HURRICANE IKE FLOODED AREAS: BEAUMONT-PORT ARTHUR AREA, TEXAS GULF COAST

New geoenvironmental maps of the upper Texas Gulf Coast corridor have been created to address ongoing resource management and environmental issues. The Beaumont-Port Arthur area, partly within a chenier-strandplain setting, contains one of the most extensive areas of salt, brackish, and fresh marshes in Texas. Substantial wetlands have been lost in this area owing to subsidence caused by active surface faults, dredging for navigation channels, saltwater intrusion through dredged channels, and sea-level rise, among others. The area also contains economically important infrastructure of the petroleum industry, including oil fields, refineries, chemical plants, pipelines, and strategic petroleum reserves. Geologic mapping of the area includes Holocene and Pleistocene geologic units associated with coastal depositional environments. Pleistocene units include Beaumont Formation distributary, interdistributary, and abandoned-channel deposits. Modern and Holocene units consist mostly of beach, dune, tidal-flat, washover, levee, marsh, and swamp deposits. This area, similar to other Gulf of Mexico coastal areas, is subject to seasonal hurricanes and tropical storms, such as Hurricane Rita, 2005; Hurricane Humberto, 2007; and Tropical Storm Eduard, 2008. The detailed maps produced by this STATEMAP project were used in conjunction with satellite imagery to determine the location and magnitude of hurricane flooding relative to geoenvironmental units.

Hurricane Ike made landfall on September 13^th, 2008, at Galveston Island, Texas. A Landsat TM 5 scene, dated September 29, 2008, was classified using a Tasseled Cap transformation to determine standing water remaining 16 days after hurricane landfall. A relatively small amount of high salt marsh remained flooded, and a slightly larger amount of seasonally flooded fresh marsh also remained flooded 16 days postlandfall. Sustained floodwater was controlled by geologic structures that inhibited drainage. The Port Arthur levee protected most upland areas, but some uplands flooded, possibly owing to geologic factors.