A CLASSIFICATION OF NATURAL RIVERS

A classification system for natural rivers is presented in which a mor phological arrangement of stream characteristics is organized into rel atively homogeneous stream types. This paper describes morphologically similar stream reaches that are divided into 7 major stream type cate gories that differ in entrenchment, gradient, width/depth ratio, and s inuosity in various landforms. Within each major category are six addi tional types delineated by dominate channel materials from bedrock to silt/clay along a continuum of gradient ranges. Recent stream type dat a used to further define classification interrelationships were derive d from 450 rivers throughout the U.S, Canada, and New Zealand. Data us ed in the development of this classification involved a great diversit y of hydro-physiographic/geomorphic provinces from small to large rive rs and in catchments from headwater streams in the mountains to the co astal plains. A stream hierarchical inventory system is presented whic h utilizes the stream classification system. Examples for use of this stream classification system for engineering, fish habitat enhancement , restoration and water resource management applications are presented . Specific examples of these applications include hydraulic geometry r elations, sediment supply/availability, fish habitat structure evaluat ion, flow resistance, critical shear stress estimates, shear stress/ve locity relations, streambank erodibility potential, management interpr etations, sequences of morphological evolution, and river restoration principles.