erosion of river valley takes olace in which course

Full Answer

How are valleys gradually widened due to lateral erosion?

The valleys are gradually widened due to lateral ero­sion with the advancement of the stage of cycle of erosion and they become quite broad with flat valley floor and uniform or rectilinear valley side slopes during mature stage or valley development and fluvial cycle of erosion.

What is the process of river erosion?

Erosion is the process that wears away the river bed and banks. Erosion also breaks up the rocks that are carried by the river. Hydraulic action - This is the sheer power of the water as it smashes against the river banks. Air becomes trapped in the cracks of the river bank and bed, and causes the rock to break apart.

How does the river change over its course?

Moving from the upper course to the lower course, the rates of erosion, transportation and deposition change. Erosion is the process that wears away the river bed and banks. Erosion also breaks up the rocks that are carried by the river. Hydraulic action - This is the sheer power of the water as it smashes against the river banks.

What are the landforms formed by river erosion?

The significant landforms resulting from fluvial erosion by streams include river valleys, waterfalls, pot holes, structural benches, river terraces, river meanders, ox-bow lakes and peneplians etc. Erosional Landform # 1. River Valleys: The valleys carved out by the rivers are signifi­cant erosional landforms.

Where does river erosion take place?

It is most common in the upper course of the river. The energy that is left after overcoming friction leads to the channel getting deeper. Lateral erosion erodes the banks of the river. This is more common in the middle and lower courses of a river.

What is the course of a river?

A river is split up unto 3 parts - upper course, middle course and lower course. Each is defined by particular variations of features such as discharge speed, the width and depth of the river bed, the landscape and many more. The upper course of a river is where the river begins its path toward the sea.

Which stage of the river is formed by erosion?

River stagesStageMain activityUpper course (steep gradient)Vertical (downward) erosionMiddle course (gentle gradient)Lateral (sideways) erosion starts, transportationLower course (very low gradient)Deposition

What is middle course of a river?

The middle course of a river is found on gently sloping land, and is typically identified by its meandering path - the sweeping side to side curves. The middle course has two main features - meanders and ox-bow lakes.

What happens in upper course of river?

As the river moves through the upper course, it cuts downwards. The gradient here is steep and the river channel is narrow. Vertical erosion in this highland part of the river helps to create steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges.

What is lower course of a river?

In the lower course, the river has a high volume and a large discharge. The river channel is now deep and wide and the landscape around it is flat. However, as a river reaches the end of its journey, energy levels are low and deposition takes place.

What are the three course of river?

If we look into the whole length of a river we will notice that it has three definite courses: 1. The Upper or Mountain Course 2. The Middle or Plain Course 3. The Lower or Deltaic Course.

What are the three stages of the river course?

Solution. From the source to its mouth, a river is divided into three main sections – Upper Course, Middle Course, and Lower Course.

What happens in the second course of the river?

As the river erodes laterally, to the right side then the left side, it forms large bends, and then horseshoe-like loops called meanders. The formation of meanders is due to both deposition and erosion and meanders gradually migrate downstream.

What type of erosion occurs in the lower course?

The channel is wider and deeper as a result. C - in the lower course there is a lot less erosion, with only some lateral erosion. The channel is at its widest and deepest.

What is middle and lower course?

Middle course The second stage of a river, where the land is flatter and the river wider. Lower course The land is flat and the river is at its widest. Channel The river bed and banks in which water flows. V-shaped valley The river in the upper course flows through steep gradients.

What is the process that wears away the river bed and banks?

Erosion is the process that wears away the river bed and banks. Erosion also breaks up the rocks that are carried by the river. There are four types of erosion : Hydraulic action - This is the sheer power of the water as it smashes against the river banks.

What happens when a river meets more resistant rock?

If the river meets more resistant rock it will flow around the rock. This produces interlocking spurs. The river erodes the valley bottom, but the valley sides are broken down by weathering.

How do rocks move?

The broken rock fragments (as a result of weathering) move down the slope through mass movements. These can be rapid, such as landslides or slow as with soil creep: 1 Landslides are occasional, rapid movements of a mass of earth or rock sliding along a steep slope. They can occur after periods of heavy rain, when the water saturates overlying rock, making it heavy and liable to slide. 2 Soil creep is a very slow movement, occurring on very gentle slopes because of the way soil particles repeatedly expand and contract in wet and dry periods. When wet, soil particles increase in size and weight, and expand at right angles. When the soil dries out, it contracts vertically. As a result, the soil slowly moves down slope.

What is a slow movement of a mass of earth or rock?

These can be rapid, such as landslides or slow as with soil creep: Landslides are occasional, rapid movements of a mass of earth or rock sliding along a steep slope. They can occur after periods of heavy rain, when the water saturates overlying rock, making it heavy and liable to slide.

What is river erosion and its characteristics

To start this topic, we will first talk about the definition of river erosion and its characteristics . We can say that this type of erosion is the wear of the land surface produced by the water channeled into river waters , that is, the water of rivers and also in streams, torrents or other water currents.

Types of river erosion

Now that we know what river erosion is and what it consists of , we will delve further into the subject and we will tell you about the different types of river erosion that exist:

Consequences of river erosion

The reliefs formed by river erosion are one of the consequences of this process. However, we must mention that within river processes, river floods also occur, which are river overflows that cause excessive water content around the riverbeds.

Examples of river erosion

Finally, in this section we will briefly describe some examples of river erosion :

Which erosion is most visible in the upper course?

We can usually see the most vertical erosion in the upper course. 2. Lateral Erosion. If you take a look at a cross profile diagram of a river, then it is easy to see that rivers widen at certain points.

Why does erosion occur?

As you can see, one of the main causes of erosion actually occurs because of materials that are being transported downstream. Any material that is broken away has to be transported and there are four ways in which this can happen:

What are the factors that play a role in erosion?

When we are talking about both vertical erosion and lateral erosion, there are four key factors that come into play: When we are talking about erosion, abrasion is one of the key factors that plays a prominent role. As rivers flow, they pick up material. This material can then scrape along the sides of the channel.

What is the role of hydraulic action in a river?

Before abrasion can take place, hydraulic action has an important role to play. The sheer force of the water in the river breaks rock particles away.

What are the two types of erosion?

Erosion. Erosion shapes the landscape around rivers, but two types of erosion are actually occurring at the same time. Erosion. They are as follows: 1. Vertical Erosion. Vertical erosion is really easy to spot because we can see how deep the river valley is when we look at cross profile diagrams.

What is the path that a river follows?

When we refer to rivers that flow downhill, we call the path that they follow their course. Most rivers have upper, middle and lower courses. The former is closest to the source of the river and the latter is closest to the mouth of the river. Naturally, the course that a river follows affects the landscape that surrounds the river because ...

What does it mean when a valley has a cross profile?

If you are offered a cross profile diagram of a valley that appears to have sides that slope gently and quite a deep channel of water in the bottom, then that usually means that you are looking at the middle course of a river, where the gradient is medium. If you are offered a cross profile diagram of a valley that appears to be flat ...

The mechanism of humid erosion

Humid erosion involves the entire aspects of shaping the effects of running water from the activities of rainwater to that of the rivers.

The processes of river action

The river carries a lot of eroded material and forms the river’s load which can be categorised into three types –

River erosion and transportation

The process of erosion and transportation goes on simultaneously in rivers comprising of the processes given below:

What is the name of the type of erosion that occurs in the upper course of a river?

As a result, the source of the river retreats. This type of erosion of the river is called Headword Erosion. The sources of Sutlej and Koshi have retreated towards Tibetan side and of Kaveri towards west in western ghats. The other two important formations of the upper course of a river are—rapids and waterfalls.

Which river valley takes the shape of I instead of V?

The river valley takes the shape of I instead of V. The Grand Canyon of the river Colorado of U.S.A. is one of the best examples. On the other hand, when river flows through soft rocks in the heavy rainfall areas erosion takes place towards the head of the river in addition to vertical and lateral erosion.

What is the meandering channel of the Dhansiri River?

The additional sediments carried by the river during the floods are deposited in this part. The channel is sometimes blocked, the river changes its course very often and becomes winding. Such a winding channel is known as a meander. The lower part of the Dhansiri River of Assam has a highly meandering course.

What are the main activities of a river in the upper course?

Erosion and transportation are the main activities of a river in the upper course. A river has a deep and narrow channel in this stage. Moreover, some of the rocks over which a river flows are very hard, while the others are soft. As a result of this, the river course is not smooth.

Where are oxbow lakes?

There are many ox-bow lakes on the two sides of Beki and Dhansiri rivers of Assam. At the time of flood, water inundates the low-lying area by the side of the river. The silt carried by the flood is thus deposited in this area year after year and a plain is built up. Such a plain is known as flood plain.

What is the last part of a river near its mouth called?

The last part of a river near its mouth is called the lower course. In this part the slope of the river bed is not very steep. The current is also very slow. Deposition is the main activity of a river at this stage.

What is the name of the formation that flows through the river?

In that situation the two sides of the river become so steep that they become almost vertical. The formation is known as Gorge. There are many gorges on the upper course of the Brahmaputra, the Indus, and the Ganges.

What are the processes that cause erosion in rivers?

There are four main processes of erosion that occur in rivers. These are: hydraulic action; abrasion / corrasion; attrition; and. corrosion. Hydraulic action. The pressure of water breaks away rock particles from the river bed and banks. The force of the water hits river banks and then pushes water into cracks.

What are the processes of erosion?

There are four main processes of erosion that occur in rivers. These are: 1 hydraulic action; 2 abrasion / corrasion; 3 attrition; and 4 corrosion.

What is the competence of a river?

The competence of a river is the maximum particle size that a river can transport at a particular point. The Hjulström curve shows the relationship between river velocity and competence. It shows the velocities at which sediment will normally be eroded, transported or deposited.

What are the types of erosion?

Types of erosion. The energy in a river causes erosion. The bed and banks can be eroded making it wider, deeper and longer. Headward erosion makes a river longer. This erosion happens near its source. Surface run-off and throughflow cause erosion at the point where the water enters the valley head.

What happens when a river scours the bed?

Where depressions exist in the channel floor the river can cause pebbles to spin around and turn hollows into potholes.

What makes a river channel deeper?

Vertical erosion makes a river channel deeper. This happens more in the upper stages of a river (the V of vertical erosion should help you remember the V-shaped valleys that are created in the upper stages). Lateral erosion makes a river wider. This occurs mostly in the middle and lower stages of a river.

How does transportation begin in a river?

Transportation of material in a river begins when friction is overcome. Material that has been loosened by erosion may be then transported along the river. There are four main processes of transportation. These are:

What are river valleys?

River Valleys: The valleys carved out by the rivers are signifi­cant erosional landforms. The shape and dimension of fluvially originated valleys change with the advance­ment of the stages of fluvial cycle of erosion. The valley formed in the youthful stage of fluvial cycle of erosion and in the initial stage of valley development is V-shaped ...

Why are the valleys widened?

The valleys are gradually widened due to lateral ero­sion with the advancement of the stage of cycle of erosion and they become quite broad with flat valley floor and uniform or rectilinear valley side slopes during mature stage or valley development and fluvial cycle of erosion.

How are gorges formed?

Gorges are formed due to active downcutting of the valleys through the mechanism of pothole drilling during juvenile (youth) stage of the fluvial cycle of erosion. Gorges are also formed due to recession of water falls. Most of the Himalayan Rivers have carved out deep and narrow gorges. ADVERTISEMENTS:

How many types of slopes are there in a meander belt?

Each bend of a meander belt has two types of slopes of valley sides: (1) One side is charac­terized by concave slope where the channel strikes the valley sides directly, with the result concave side is subjected to severe erosion resulting into the formation of vertical cliffs.

Why are flood plains rejuvenated?

The flood plains consist of thick deposits of alluvia and gravels. The rivers are rejuvenated due to sudden negative change (fall) in sea-level. Conse­quently, the erosive capacity of the rivers is increased substantially. Thus, rejuvenated rivers deepen their valleys due to accelerated rate of vertical erosion.

What is a waterfall in a river?

A wa­terfall may be defined as a vertical drop of water of enormous volume from a great height in the long profiles of the rivers. Rapids are of much smaller dimension than waterfalls. Generally, they are found upstream from the main falls but they are also found independently.

Why do waterfalls have plunge pools?

In fact, plunge pools are generally formed at the base of waterfalls due to pounding of rocks by gushing water of the falls (waterfalls). Many of the river valleys are studded with numersous pot­holes in Chotanagpur highlands where the rivers have been rejuvenated due to upliftment effected during Tertiary period.

Where does erosion take place in a meander?

As we’ve just seen, strong erosion takes place on the outside bend of a meander while deposition takes place on the inisde bend. As a result, the neck of a meander narrows. During extremely high discharge (e.g., a flood), it’s more efficient for a river to flow accross the neck of a meander rather than around it.

Why are the sides of a valley steep?

If the valley is composed of hard rock the valley sides will be very steep because they won’t be weathered easily. Waterfalls (Geological) Waterfalls develop when a change of lithology (rock type) takes place along the river’s course resulting in differential erosion.

How is the width of a floodplain determined?

The width of a floodplain is determined by the sinuosity of the river and how much meander migration takes place. If there’s a lot of meander migration, the area that the river floods on will change and the floodplain will become wider. Levees. Levees are natural embankments produced, ironically, when a river floods.

Why do levees burst?

Levees aren’t permanent structures. Once the river’s discharge exceeds its bankfull discharge1, the levees can be burst by the high pressure of the water.

What is a bend in a river that form as a river’s sinuosity increases?

Meanders. Meanders are bends in a river that form as a river’s sinuosity increases. The sinuosity of a river is a measurement of how much a river varies from a straight line. It’s a ratio between the channel length and displacement (straight line distance) between two points in the river’s course:

How do eddie currents affect the river bed?

These currents erode the river’s bed and create small depressions in it. The creation of eddie currents as a result of bedload in a river. As these depressions deepen, pebbles can become trapped in them. As a result of the eddie currents, the pebbles drill into the depressions making them more circular, wider & deeper.

How does a river's load work?

In the upper course of a river, its load is large and mainly transported by traction along the river bed. When flowing water encounters bedload, it is forced over it and downcuts behind the bedload in swirling eddie currents. These currents erode the river’s bed and create small depressions in it.