H13F-1610
Varying effects of geomorphic change on floodplain inundation and forest communities
Monday, 14 December 2015
Poster Hall (Moscone South)
Richard Keim1, Erin L Johnson1, Brandon L Edwards1, Sammy L. King2 and Cliff R Hupp3, (1)Louisiana State University, Baton Rouge, LA, United States, (2)US Geological Survey, Louisiana Cooperative Fish and Wildlife Research Unit, Baton Rouge, LA, United States, (3)U.S. Geological Survey, Reston, VA, United States
Abstract:
Overbank flooding in floodplains is an important control on vegetation, but effects of changing flooding are difficult to predict because sensitivities of plant communities to multidimensional flooding (frequency, depth, duration, and timing) are not well understood. We used HEC-RAS to model the changing flooding regime in the lower White River floodplain, Arkansas, in response to rapid incision of the Mississippi River in the 1930s, and quantified flood frequency, depth, and duration by forest community type. Incision has decreased flooding especially in terms of frequency, which is one of the most important variables for ecological processes. Modeled depth-duration curves varied more among floodplain reaches than among forest communities within the same reach, but forest communities are now arranged in accordance with new flood regimes in place after river incision. Forest responses to subtle geomorphic change are slower than other vegetation communities, so detection of the full ramifications of ecohydrologic change may require decades.
