Stream Networks
Definition
Stream networks are directed graphs of channels that convey water from headwaters to outlets. They are derived from hydrologically conditioned DEMs, hydrography surveys, or lidar, and include attributes such as order, slope, bankfull width, and flow permanence. Networks support routing models, habitat connectivity studies, and water-quality tracing. Maintaining correct connectivity and direction is essential for meaningful analysis.
Application
Watershed managers delineate catchments and compute pollutant travel times; fisheries biologists assess barriers; engineers design culverts and bridges; and emergency responders plan spill containment. Urban planners reconcile natural channels with storm sewers to understand compound flooding.
FAQ
What distinguishes perennial, intermittent, and ephemeral segments in mapping?
Perennial flow year-round; intermittent flow seasonally; ephemeral carry water only after storms. Combine field observations, baseflow indices, and vegetation signatures to classify permanence.
How do braided channels challenge network representation?
Multiple shifting paths require representing anabranches and seasonal connectors; relationship classes or time-aware networks help maintain realistic routing.
Why is vertical integration with culverts and storm pipes important?
Flows can dive underground and reemerge; without connectors the model shows false sinks or delays, misinforming flood or spill analyses.
How should stream order be chosen for the task at hand?
Strahler emphasizes hierarchy; Shreve emphasizes cumulative tributary count. Pick the scheme that aligns with ecological or hydraulic questions being asked.
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