Wednesday, November 15, 2006 - 1:00 PM

Impacts of Prehistoric Agricultural Landscapes on Changes in Stream Channels in Mexico and the Southwest.

William E. Doolittle, University of Texas, Department of Geography and the Environment, Austin, TX 78712

Stream channels in the American Southwest and northern Mexico are highly dynamic.  Vagaries in rainfall distribution, amounts, and timing result in unpredictable runoff and stream discharge.  As a result, aggredation, degradation, migration, and avulsion are common fluvial processes.  Farmers today, historically, and prehistorically have endeavored to manage stream channels in order to protect their floodplain fields.  Sometimes they were very successful, at least for brief periods; sometimes they were not.  Conversely, the agricultural landscapes created in the process of clearing, leveling, and constructing irrigation canals on floodplain lands have also affected stream channels.  The complexity of this agricultural-stream channel relationship is articulated in this paper.