STREAM‐CHANNEL INCISION FOLLOWING DRAINAGE‐BASIN URBANIZATION

摘要: ABSTRACT: Urbanization of a drainage basin results in pervasive hydrologic changes that turn initiate long-term stream channels. Increases peak discharges and durations high flows result either quasi-equilibrium channel expansion, where cross-section area increases near-proportion to the discharge increase, or catastrophic incision, occur far out proportion initiated them. Field data modeling rapidly urbanizing basins King County, Washington, define conditions flow, topography, geology, roughness identify streams susceptible incision. Channel slope geologic material are particularly critical; thus simple map overlays, nearly irrespective contributing area, provide valuable planning tool for identification terrain. Where such exist, basal shear stress provides quantifiable parameter predicting likely problems, although knickpoints typical settings confound calculation sediment-transport rates. urbanization proceeds areas, effective mitigation incision hazards requires degree stormwater control excess standards typically applied present development activity.