Features of the upper course

Rapids

Turbulent flow that are caused by the sudden change in gradient causing faster flowing water

Braided Channels

• The river is forced to split into several channels seperated by islands.
• Occurs when a river has variable discharge-large loads of sand and gravel

• River flows over alternating bars of sediment and the water is forced to weave around them 
• The river will take the path of least resistence
• Creates shallow sections and deeper sections
• Maximum velocity occurs towards the outside of the bank and results in erosion by undercutting creating a river cliff
• Water is slowest on the inside of the meander meaning it has less energy therefore depostion occurs, forming a point bar
• This continues over time causing the bend to become sharper and sharper 
• The cross section is asymmetrical-deeper near the river cliff and shallow near the point bar
• Once the meander is developed there is a corkscrew type movement called helicoidal flow-water moves from the outside to the inside of the bend
• Meander migrates laterally and downstream

• Feature of erosion and deposition
• Horse shoe shaped lake seperate from the river
• Water is stagnant and lake gradually silts up and becomes more crescent shaped
• Stretch of marsh called meander scar
• Formed by increasing sinuosity of a meander
• Most erosion on the outer bank
• Deposition on the inner bank
• Neck of the meander becomes narrower

• If a rejuvenated river occupies a valley with well developed meanders, renewed energy results in them becoming incised or deepend
• Erode vertically
• Incision is slow and lateral
• Erosion occurs and on ingrown meander might be produced 
• Calley becomes asymetrical with steep cliffs on outer bends and gentle slip off slope on the inner bends
• Rapid incision where dowcutting or vertical erosion dominated 
• Valley is more symetrical with steep sides and a gorge like appearance, these are entrenched meanders

• Widens
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• Deepens
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• Particles get smaller
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• Particles are rounder

• Meander-bends in the river
• Ox Bow Lake-when the river has enough energy to cut off the meander
• Rejuvenation-sudden increse in energy
• Incised meander-More symetrical

• Feature of deposition
• At the mouth of a river
• Deposition occurs when the velocity and sediment carrying capacity decrease
• Bedload and suspended material are dumped
• Flocculation occurs as fresh water mixes with sea water and clay
• Only form when the rate of depostion exceeds the rate of sediment removal
• To form they need:large sediment load of the river, small coastal tidal range and weak currents, limited wave action and little transportation of sediment
• Larger and heavier particles are deposited first which form the topset beds
• medium sized particles travel further before they are deposited as steep angled wedges of sediment forming foreset beds
• Finest particles travel furthest into the lake before deposition and form topset beds

• Created from erosion and deposition
• Flat areas of land on eith side of the river
• Alluvium-river deposited clay and silts
• Over time it becomes wider and deeper
• Width is determined by the amount of meander migration and lateral erosion
• Lateral erosion is most powerful downstream of the apex of the meander bend

• During a flood thick, coarse sediment is deposited at the channel edges
• Thin and fine material deposited over outer parts of the floodplain
• Natural levees buiold up by floods
• More floods increase the size of levees