Download
1 / 16
160 likes | 234 Views
This review delves into the physics behind river flow and erosion, examining the processes shaping river channels. It scrutinizes the impact of floods and tectonic settings and analyses the graded profile concept. Topics such as gravity as a driving force, solar energy influence, and balance of erosion and sediment supply are explored. The modes of sediment transport, downstream organization, and channel mobility are examined. Consideration is given to fluid forces on sediment, mean water velocity distribution, and idealized flow patterns in alluvial and meandering rivers. The effects of climate change on river channels, gorges, knick zones, and glacial hanging valleys are discussed.
E N D
River morphology and process class consider physics of flow and erosion review river taxonomy examine the germane processes that control the shape of river channels consider the graded profile consider the impact of floods and tectonic setting on river channels
Gravity = driving force Solar = energy source • Gravity responsible for movement of water down gradient, PE = mgh ~ h • Precipitation maintains supply of fluid, driven by solar forcing • Tectonics maintains gradient, driven by erosion and endogenic forces • Consider fluid forces acting on sediment, critical shear stress (crit, need to detach grains • Balance of erosion, sediment supply shapes channels 1
MODES OF SEDIMENT TRANSPORT • Sliding • Rolling • Saltation • SHOW FLASH MOVIE
Taxomony 2
Water velocity is not uniform with depth Consider friction and laminar flow; mean velocity at 0.6 d
Idealized flow patterns Alluvial, meandering river Dye tracing 3
Graded profile, idealized form • rivers will try and adjust to minimize energy gradient • tectonics and climate change get in the way
Can the river keep up? Gorges reflect cutting Knick zones reflect inability to cut quickly enough Taiwan
What does climate change do? Glacial hanging valleys, bedrock channel erosion
