Channel head locations in forested watersheds across the mid-Atlantic United States: A physiographic analysis

Abstract

Channel heads are the beginning of river networks and thus knowing their location is important in assessing water resources and health threats to fluvial ecosystems. Despite their importance, most channel heads are unmapped. Remote sensing technologies have not yet proven effective under forested canopies, suggesting that predictive models of channel head locations are the best solution to the impracticality of field-mapping the millions of these features that exist in the U.S. alone. In this study, we compared the locations of 253 field-mapped channel heads in forested watersheds across five different physiographic provinces to a suite of landscape attributes to develop statistical relationships and explanations for the occurrence of channel heads. Topographic attributes were best correlated to catchment source areas of channel heads, with local slope being the primary explanatory variable in one physiographic province, local plan curvature in another, and average profile curvature in the other three. We also found an approximate 1:1 relationship between average plan curvature and average profile curvature for channel heads, suggesting that channel heads in the mid-Atlantic U.S. tend to occur at the outlet of bowl-shaped catchments. Although our results are region-specific, the insight gained by investigating site specific processes across a large physiographically diverse area will help promote more general and robust models that can be applied in a range of landscapes.