GETTING TO THE OTHER SIDE: A LOOK AT ROAD-STREAM INTERACTIONS ADJACENT TO LOW WATER STREAM CROSSINGS ON THE OZARK-ST. FRANCIS NATIONAL FOREST, ARKANSAS

Interactions between roads and surface water have been studied and well documented across a variety of environments (USDA FS, 1998). Critical interactions occur where roads and streams intersect; at this interface a host of environmental responses or impacts can be observed. The objective of this project is to determine the range of expected environmental responses that result from crossing interactions on the Ozark-St. Francis National Forest. Eight low water stream crossing (LWSC) sites, representative of crossings encountered in the Boston Mountain Ecoregion, were selected to investigate stream channel responses over the last seven decades. Aerial photography was acquired, georeferenced, and analyzed in a GIS to discern and quantify stream morphology patterns. Stream width and sinuosity were measured from the aerial photography upstream, concurrent, and downstream of each site. Field assessments documented the local geomorphic processes and stream characteristics. When compared over time, changes in channel width and sinuosity did not change significantly. Natural channel processes dominated the responses found for unimproved crossing sites, and these interactions were less complex than those observed at improved crossing sites. Thus the variability associated with the natural processes obscured the detection of LWSC-induced change at the scale and timeframes used in this study.