Using Remote Sensing to Assess Inundation Extent and Habitat Condition in Large River Floodplain Environments

Large river floodplains provide valuable aquatic and upland habitats for a large diversity of both terrestrial and aquatic organisms.  The frequency, timing, duration, and spatial extent of inundation drive habitat quality in floodplains and determine the suitability of these important habitats for floodplain dependent organisms.  This study used multitemporal analysis of remotely sensed satellite imagery captured at a variety of river stages to more accurately describe the patterns of inundation, water quality, and flow at a landscape scale.  Landsat TM 5 and 7 (TM) images of the Atchafalaya basin in southern Louisiana were classified into categories of dry land, open turbid water, open black water, turbid water in flooded lands, black water in flooded lands, and floating aquatic vegetation.  Each image was captured during leaf-off conditions to optimize delineation of ground conditions.  The frequency of occurrence for each of these categories can then be variably used to define long term habitat quality for a variety of organisms.  In the Atchafalaya basin, for example, turbid water usually indicates higher connectivity with well-oxygenated river water, while black water and areas having high frequency of floating aquatic vegetation indicates poorly oxygenated conditions.  A similar multitemporal landscape analysis was also conducted for the lower Mississippi river and coupled with insitu water quality measurements and telemetry to identify the floodplain characteristics that may define localized habitat suitability for alligator gar in the vicinity of the St. Catherine Creek National Wildlife Refuge.  This powerful combination environmental and biological sampling with multitemporal imagery analysis may be further used to identify other areas within the floodplain that may be candidate areas for protection and conservation.