RIVER PROCESSES- Deposition

A river deposits when there is a decrease in its level of energy= it is no longer competent to transport its load.

 Deposition usually occurs when:

• A reduction - gradient of the river (e.g when it enters a lake)
• The discharge = reduced (such as during and after a dry spell of weather)
•  Shallow water  (inside of a meander)
• Increase - calibre (size) of the load (due to a tributary bringing in larger particles, increased erosion along the river’s course, or a landslide into the river)
• The river floods + overtops its banks= reduced velocity on the floodplain outside the main channel

 Largest fragments = first to be deposited then - successively smaller particles
Finest particles = may never be deposited. 
Pattern of deposition = reflected in the sediments found along the course of a river. 
The channel of upland rivers = filled with large boulders. 
Gravels, sands and silts = carried further +  often depoisted further downstream. 
Sands and silts are deposited = flat floodplains either side of the river in its lower course.