Panel discussion of stream classification systems

Classification systems provide one means for generalizing, organizing, and categorizing sets of diverse items into groups. Stream channels tend to fit into broad categories (e.g., braided, meandering, sinuous, and straight) that suggest the utility of having some type of stream classification system. Recently, "natural channel design" has been advocated as a goal for stream alterations and has become the heart of some stream classification systems. Similarly, "channel evolution" has been recommended as one means for gaining insight to dominant channel processes. Both approaches rely on observations and comparisons of channel condition and geomorphic form. However, the physical appearances of streams can be misleading, as they often represent only fleeting glimpses at conditions, usually transitory, that reflect many different states of anthropogenic disturbance. This poses a particular difficulty in terms of stream channel restoration efforts, as there are few or no "undisturbed" streams in many regions of the country against which to make reference in order to understand what types of restoration goals and potentials may be relevant. Nevertheless, several classification systems have been developed that are used to assist in or even to guide stream alteration activities, including stream restoration. This panel reviews the features of classification systems and considers their "pros and cons" for various applications, including stream restoration. Copyright ASCE 2005.