Classification of morphology and habitat in streams and rivers: application to river management.

Abstract

Six stream habitat (morphology) classification systems were reviewed from the aspect of spatial scale and location within watershed. Classification systems at a segment scale (10³-10⁴ channel width) covered whole river segments within a watershed, but they did not adequately classify mountain streams. Segment subdivision using a reach-scale classification system can solve this issue. Classification systems at a reach scale (10¹-10²⁾ and a channel unit scale (10⁰-10¹⁾ were constructed for ≤3^rd-order mountain streams. These classifications can be applied to ≥4^th-order rivers in canyons, valley plains, and coastal alluvial plains. Subunit types were commonly classified according to various purposes and targets. However, general subunit types can be based on river morphology and planar flow conditions that are important spatial units, particularly in large alluvial rivers. Our review found that existing classification systems and general subunit types can be applied to better understand the overall physical and ecological features of streams and rivers, and can promote effective river management.