13. Create a flow chart of the three courses of a river and give examples of landforms made in each course.
Answers
Answer:
The river has three different "courses", the Upper Course, Middle Course and Lower Course, each with their own different characteristics. waterfalls, interlocking spurs. meanders, floodplains.
land forms formed by river are :-
Natural Levees—River may be immediately flanked by a buildup of sediment that forms natural levees. ...
Natural Levees—River may be immediately flanked by a buildup of sediment that forms natural levees. ... Oxbows and oxbow lakes—See below, features of a Meandering Stream Channel.
Natural Levees—River may be immediately flanked by a buildup of sediment that forms natural levees. ... Oxbows and oxbow lakes—See below, features of a Meandering Stream Channel.Point Bars—See below, features of a Meandering Stream Channel.
Natural Levees—River may be immediately flanked by a buildup of sediment that forms natural levees. ... Oxbows and oxbow lakes—See below, features of a Meandering Stream Channel.Point Bars—See below, features of a Meandering Stream Channel.Terraces.
Explanation:
Before looking at specific river landforms it is important to look at how the river channel itself changes downstream. We have already looked at how the river channel in the upper course is shallow and narrow with large bedload that disrupts the efficiency of flow. The bedload is derived mainly from mass movements from the valley sides and eroded rock from the bed and banks of the channel. The valley profile is really just an extension of the channel itself; it follows a symetrical v-shaped form. This narrow valley and river channel is caused by vertical erosion as a result of the high potential energy of the river. As the river stretches downstream both its velocity and discharge increase. Its velocity increases due to more efficient flow and reduced channel roughness. The discharge increases because the catchment area of the drainage basin has increased along with the number of tributaries feeding water into the river. As a result of this increased discharge the river, in its attempt to balance its energy erodes laterally, widening as well as deepening the river channel. At times, the river will exceed the banks and flood across the flatter section of the valley, initially in a youthful phase a floodplain may be eroded out of the valley. Over time a flat extended floodplain devlops either on both sides of the river or dominant on one side. Again in an effort to balance its energy and discharge the river will meander, creating asymetrical river channels; characterised by steep river cliffs on the outside bend of the meander and gentle slip-off slopes on the inside bend of the meander. Unregulated floodplains support permanent and semi-permanent wetlands. Further downstream the floodplain grows in size on both sides of the river as the river channel grows in width and depth. The channel shape becomes once again more symetrical as the channel widens. The meander length and meander belt both increase in size and the erosion of the outside bend slows down.
