Lake Michigan basin, USA: Valley Segment Ecological Classification (VSEC)

Valley Segment Ecological Classification (VSEC).  An ecological river classification involves the identification of structurally homogeneous spatial units which emerge along the channel network as a result of catchement processes interacting with local physiographic features. Observations of Michigan rivers suggest that the natural ecological unit, as defined by the spatial scales of riverine physical and biological porcesses, is most closely approximated by the physical channel unti termed the valley segment. Valley segments are generally quite large, characterized by relative homogeneity in hydrologic, limnologic, channel morphology, and riparian dynamics. Valley segment characteristics often change sharply at stream junctions, slope breaks, and boundaries of local landforms.