River and its landforms

Take a tray and keep it in a slant position making some angle with the ground and pour some water on the tray, you'll find that water flows from the higher end to the lower end. similarly, when water flows from higher land (land with high elevation )to lower end(land with low elevation) over a long distance it is called a River 

The route that a river follows is called the course of the river 

The point at which a river originates (starts flowing ) is called its source. 

snow mountains are the source for some of the rivers flowing in many parts of the globe, in the summer season when the snow melts, the water flows down the mountains in small streams, these streams join to form rivers. the rivers formed by such streams is called snow-fed rivers

Some rivers depend on rain for water. heavy rains in mountains and plateaus from streams, these streams join to form rivers. the rivers formed by such streams are called Rain-fed rivers. Rain-fed rivers don't have a single source but they flow in a particular river. a river grows bigger in its course as other rivers join it, these other rivers are known as tributaries. the place where a river ends or joins an ocean or sea is known as the mouth of a river. 

when a river flows from the source to the mouth, Different landforms are created in between due to Erosion and Deposition.

Stages of a Rivers Journey

the course of the river is divided into three sections 

i)Upper course

ii)Middle course

iii)Lower course

Upper course

As it is the source it has a little water but the river at this has the maximum speed(fast-flowing) due to the steep mountain slope. At this stage, there is a lot of erosion, moth of the energy (speed) is lost during the erosion of the landscape. 

Erosion can occur in four ways

• Hydraulic action: the force of the moving water wears away the bank and bed of the river
• Abrasion: small stones carried by the water wears away the bank and bed of the river 
• Attrition: small stones carried by the water are worn down and broken up as they collide with each other.
• solution: rocks and soil are dissolved by the acid in the water

Landforms in the upper course 

• Potholes
• V-shaped valley
• interlocking spurs 
• waterfalls

Potholes: these are cylindrical holes drilled in the bed of the river extending from a few cm to m. in the upper curse of a river its load is large and mainly transported by rolling along the river bed. when the load in the river water encounters with river bed it creates holes in the river bed the process continues and the holes develop as potholes.

V-shaped valley

vertical erosion is dominant in the upper course of the river compared to lateral erosion. the upper course of the river carries stones and rocks while flowing downhill it removes maximum sediments present on the bottom floor of the river than riversides and carves out a valley. 

The V-shaped valley is deeper river valleys with steep sides, deep and narrow valley with steep sides is called Gorge 

Interlocking Spurs

not all the materials, surfaces that come in the way of the river can be eroded by the flow of the water. A river comes across some areas of hard rocks in its course, that it cannot erode so it flows around them creating Zig-Zag course known as Interlocking Spurs. 

Waterfalls

waterfalls are formed when a river flows over the layer of harder rocks followed by the layer of harder rock. the softer rock erodes fastly forming a step in the river bed. the force of the falling water undercuts the soft rock forming the plunge pool. the harder rock is left overhanging, as isn't having baby support it eventually collapses the fallen rock crash into the plunge pool and breaks into smaller rock pieces, these pieces swirl around and increases the size of the plunge pool & erosion. 

Middle course

in the upper course, the water erodes the landscapes. erosion breaks off the particles rock and soil, these particles are carried by along the river, they are known as Load. the load is transported from upland to lowland area by the process called River Transportation 

 Transportation occurs in four ways

• Rolling: large stones are rolled along the surface of the river
• Bouncing: smaller pebbles bounce along the bed of the river 
• Suspension: light material like sand and silt are carried by the flow of the river
• Solution: dissolved material are carried along by the river 

Landforms in the Middle course 

• Meanders 
• oxbow lakes 
• Flood plain 

Meanders: they are bends or curves along the course of the river. they are formed by erosion and deposition. erosion occurs on one side of the river and deposition on the opposite side, this process continues and makes bends sharper. 

Meanders are formed when the river's sinuosity increases. the sinuosity of a river is the measurement of how much a river varies from a straight line. it is the ratio between the observed path distance and the displacement between the two points in the river course. 

Oxbow lakes: oxbow lakes are an evolution of meanders, that undergo extensive deposition and erosion. we know that strong deposition takes place at inside bends and strong erosion takes place at the outside bend, which narrows the neck of the meander. during high discharge, it's more efficient for a river to go flow across the neck(straight) of the meander instead of flowing around it. when discharge comes to a normal level the river continues to flow at a normal level. then again deposition and erosion occur cutting of oxbow lakes from the main river course. 

Flood plains: flat area of land on either side of the river. after heavy rains river sometimes floods. when a river floods, its efficiency decreases due to an increase in friction which forces it to deposit its load. the load is deposited across the flood plain as alluvium. the alluvium is very fertile, hence flood plains are often used as farmland 

Lower course

in the lower course, the river is moving on a flat surface and it is carrying a lot of sand and silt. the river began to drop its sand and silt, from the deposition of these sand and silt different landforms are created.

Landforms in the Lower course 

• Fan-shaped plains 
• Levees
• Deltas

Fan-shaped plains: formed in the region where the tributaries join the main river. these are formed due to the deposition of material carried by the tributaries. the deposition takes place in such a way that it forms a fan-shaped structure so-called Fan-shaped plains. 

Levees: when the river floods and spread out over a flood plain, the heaviest material is deposited close to the river bank. repeated floods result in more and more deposition at the banks of the river and form levee

Delta: a triangular-shaped piece of land deposited at the mouth of the river formed due to the deposition of material that a river carries.