![]() Stream type "A" is similar to the described ∺a+, in terms of associated landforms and channel characteristics. The ∺a+ stream types are often found in valley types I, III, and VII, discussed in the next part of this module. Examples of rejuvenation may be observed where lower-slope position streams are deeply incised in over-steepened adjacent side-wall slopes, or older holocene terrace features that have cut their way through to the elevation of the existing mainstem river. ∺a+ stream types may also be found in alluvial landforms, where a change in the base level of the mainstem channel initiates a headward expansion of the tributary network through a channel rejuvenation process. The "Aa+" can often be described as high energy/high sediment supply systems due to their inherently steep channel slopes and narrow/deep channel cross-sections. The "Aa+" stream types can be associated with bedrock, and zones of deep deposition and/or be deeply incised in residual soils. Streamflow at the bankfull stage in the "Aa+" stream type is generally observed as a torrent or waterfall. The ∺a+ stream types often occur in debris avalanche terrain, zones of deep deposition such as glacial tills and outwash terraces, or landforms that are structurally controlled or influenced by faults, joints, or other structural contact zones. The bedforms are typically a step/pool morphology with chutes, debris flows, and waterfalls. ![]() Stream type ∺a+ is very steep (>10%), well entrenched, has a low width/depth ratio, and is totally confined (laterally contained). Illustrations of the Level I stream types are shown in the accompanying figure clicking on each stream type will also bring up a brief text description of that type in this text window. The Level I classification and delineation process provides a general characterization of valley types (addressed in the second part of this module), and identifies the corresponding major stream types, A through G, discussed here. The advantage of a broad, general classification is that it allows for a rapid initial delineation of stream types and illustrates the distribution of these types that would be encountered within a given study area. ![]() correlate similar general level inventories such as fisheries habitat, river boating categories, and riparian habitat with companion river inventories.assist in the setting of priorities for conducting more detailed assessments and/or companion inventories.Mapping of physiographic attributes at Level I can quickly determine location and approximate percentage of river types within a watershed and/or valley type. provide a consistent initial framework for organizing river information and communicating the aspects of river morphology.provide for the initial integration of basin characteristics, valley types, and landforms with stream system morphology.The Level I stream classification serves four primary functions: ![]()
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