Types of channel•Straight Channel•Braided Channel•Meandering Channel
Straight channels• Mainly in the upper zone• Channel located upon rock• Single channel with pools and riffles• Thalweg moves from side to side• Vertical erosion (incision) predominant• Saltation and traction main method of transport• Main landforms: V-shaped valley, waterfalls, gorges
Braided Channel• Mainly in the middle zone• Flows upon coarse alluvial material• Several roughly parallel channels intersecting at points• Whole channel system is straight but channels wander from side to side within the flood plain• Major deposition occurs after discharge decreases• Lateral erosion occurs between floods• Main landforms are multiple channels separate
Meandering• Found mainly in the lower zone• Channel flows upon fine alluvial material• Channel wander in a regular pattern from side within the flood• Lateral erosion and deposition moves channels across the flood plain as meanders• River meanders themselves move downstream• Suspensions are main method of transport• Main landforms: levees, ox-bow lakes, point bars, slip-off slope, bluffs
Long Profile of a river• Graph drawn along the course of a river from the source to the mouth• Shows that they have a concave shape with a steeper upper reach and a gentler lower reach• Ideal profile is called the ‘graded long profile’• In this ideal situation, the river is in a state of dynamic equilibrium where there is a balance between the rate of erosion and the rate of deposition• This balance is always transitory as the slope (profile) has to adjust constantly to changes in the river• These can cause short-term increases in either the rate of erosion or deposition until the state of equlibrium has again been reached
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