(C) Information contained within LCAs, such as erosion potential, fire risk and road length, is transferred to stream segments. (B) Each segment has a right-left differentiated local contributing area or LCA (tenths of a square kilometer at segment length of 100m). The Virtual Watershed includes (A) a routed analytic river with confluences, including with attributes (Table 1). Closed depressions (e.g., drainage in, not out) combined with certain soil types (hydric) and landforms such as floodplains, are used to identify land surfaces in close proximity to water tables (e.g., wetlands or wet areas), a delineation relevant to ecological classification and forest site potential.įigure 3. Widths of floodplains and valleys and their transitions from constrained to unconstrained (and vice versa) are included, attributes that have implications for aquatic habitats, flooding, and hyporheic flow (Benda et al. Tributary confluences are characterized for their potential to create morphological changes in channels and valley floors, including contributing to aquatic and riparian habitats (Benda et al. ![]() 2007) and shallow landsliding (Miller and Burnett 2007) are added (Table 1). Floodplains, terraces, alluvial fans and combinations of hillslope gradient and planform curvature that reflect hillside susceptibility to gullying (Parker et al. Other landforms and their characterizations can be included in NetMap’s Virtual Watershed. Characterizing variability in aquatic and riparian habitats could be used to tailor protection strategies based on specific environments, uniquely distributed in individual watersheds. Channels are discretized where physical properties change abruptly, such as channel gradient and width, creating segment lengths of between 50m and 200m (Miller 2002). The analytic river network is divided into short segments for identifying variability in fluvial and valley environments, including channel morphology, aquatic habitats, floodplains and terraces. ![]() Analytical rivers must encompass channels of all sizes, including the smallest headwater streams that are increasingly being recognized for their ecological importance (Richardson and Daheny 2007) but also their hazards (e.g., landslides and debris flows) (Burnett and Miller 2007). Convergence of flow, under certain constraints, leads to channels non-convergent flows represent the terrestrial landscape. Various algorithms are available to predict flow direction in grid cells and to create a “flow direction grid” (Jenson and Domingue 1988, Tarboton 1997). The analytic river is derived from surface flow paths inferred from a DEM (Figure 2).
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