river esosion

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G.E. Society’s, H.P.T Arts & R.Y.K Science College Department of Geography (2011-12) Subject- Fluvial Geomorphology Topic- Erosional Features, :

G.E. Society’s, H.P.T Arts & R.Y.K Science College Department of Geography (2011-12) Subject- Fluvial Geomorphology Topic- Erosional Features,

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Gondia Education Society's C.J. Patel College, Tirora , Dist.- Gondia 441911. Subject : FLUVIAL GEOMORPHOLOGY Topic Flow And Types of Flow Is presented by Dr. Nanabhau S. Kudnar M.A., B.Ed., SET, NET, Ph.D., M.B.A . Head, Department of Geography C.J . Patel College Tirora .

TYPES OF FLUVIAL EROSION:

TYPES OF FLUVIAL EROSION Vertical erosion Lateral erosion Headward erosion

VERTICAL EROSION :

VERTICAL EROSION When vertical erosion occur, the channel is deepen and thus the river is able to hold more water.

LATERAL EROSION :

LATERAL EROSION When lateral erosion occur, the sides are eroded and the channel is widen.

HEADWARD EROSION :

HEADWARD EROSION

EROSION :

EROSION Erosion is the process by which there is wearing away of land surface by the mechanical action. Fluvial erosion refers to the wearing away of land surface with the help of water. A river erodes its bed and sides. Erosion is the wearing away of rock by moving agent and are carried away by them.

PROCESS OF EROSION:

PROCESS OF EROSION Solution/ Corrosion The river water may also dissolve the minerals in the rock and carry them down the river. Limestone may be dissolved quickly in the river water, especially when there is high concentration, to form soluble calcium hydrogen carbonate

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Cavitation It is caused by constriction of flow which raises the velocity and hence the kinetic energy of the steam. Lead to the formation of bubble .

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Hydraulic action Water traveling at a high speed may enter the line of weakness of rock when it hit against these rocks at the side of the channel. The force may cause the rock to break and the broken pieces of rock are swept away

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Abrasion/corrasion Rocks that are carried in the river grind and erode the river side and bed. Some of the rock at the sides and bed of the channel are washed away. This type of erosion widens the channel through lateral erosion and deepens the channel by vertical erosion.

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Attrition When material in the water collide with one another, they break and become smaller particles. These particles become smoother and rounded .

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EROSIONAL FEATURES Introduction- The work of running water in the form of surface runoff or overland flow and streams is Most important of all the exogenetic or planation processes (e.g. ground water, sea waves, glaciers) Because the running water is the most widespread exogenetic process on this planet earth.

EROSIONAL FEATURES:

EROSIONAL FEATURES Definition- “The word ‘erosion’ has been derived from a latin word, ‘ erodere ’ which means to grow. Erosion is, in fact, a dynamic process which involves the removal of geomaterials from the rocks and other deposited materials”.

EROSIONAL FEATURES:

EROSIONAL FEATURES River Valley V – shape valley Gorges Canyon Interlocking Spurs Waterfalls, Rapids potholes Structural Benches.

V – shape valley:

V – shape valley In the upper course of a river, water flows quickly through a narrow channel with a steep gradient; as it does so it cuts downwards. This vertical erosion results in a number of distinctive landforms including the steep sloping v-shaped valley through which the river flows in its upper course.

GORGES:

GORGES Gorges and Canyons represent very deep and narrow valleys having very steep valley side slopes say wall-like steep valley sides. A very deep and narrow valley is called gorge and extended form of gorge is called a canyon. Gorges are also formed due to recession of water falls.

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Most of the Himalayan rivers have carved out deep and narrow gorges. The significant gorges formed due to recession of waterfalls includes hundrughage gorge on the the subarnarekha river(near Ranchi), Gorge of the raru river below johana or gautamdhara falles (east ranchi), Chachi gorge on the Bihar river (reva mp)

GORGE:

GORGE Yangtze river

CANYONS :

CANYONS Canyon are extend form of gorge. Canyon represent the very deep, narrow but long valleys. The Grand canyon of the Colorado river in the state of Arizona(USA) having a length of 482.8km and depth of 2088.3km is the most important canyon of the world.

CANYONS:

CANYONS Grand canyon Arizona(USA)

Interlocking Spur -:

Interlocking Spur - spurs are ridges of more resistant rock around which a river is forced to wind as it passes downstream in the upper course. Interlocking spurs form where the river is forced to swing from side to side around these more resistant ridges

WATERFALLS:

WATERFALLS Waterfalls or simply falls are caused because of sudden descents or abrupt breaks in the longitudinal course of the river. It due to a host of factor e.g. variation in the relative resistance of rocks, relative difference in topographic relief, fall in the sea level and related rejvenation,earth movements etc.

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A waterfall may be defined as a vertical drop of water of enormous volume from a great highest in the long profile of the rivers. there is chin of waterfall in India this is also called fall line. Indian fall line extend between the purwa or tons fall on the tons river.

WATERFALL.:

WATERFALL.

WATERFALL:

WATERFALL JOG Waterfall,Sharavati river

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A rapid is a section of a river where the river bed has a relatively steep gradient causing an increase in water velocity and turbulence . A rapid is a hydrological feature between a run (a smoothly flowing part of a stream ) and a cascade . A rapid is characterised by the river becoming shallower and having some rocks exposed above the flow surface.

Structural Benches:

Structural Benches First, the differential erosion of rocks or sediments of varying hardness and resistance to erosion can create benches. Earth scientists called such benches "structural benches." Second, other benches are narrow fluvial terraces created by the abandonment of a floodplain by a river or stream and entrenchment of the river valley into it.

POT HOLES:

POT HOLES The kettle-like small depressions in the rocky beds of the river valleys are called pot holes which are usually cylindrical in shape. Pot holes are generally formed in coarse-gained rocks such as sandstones and granites. Pot holing or pothole drilling is the mechanism through which the grinding tools.

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Pot holes of much bigger size are called plunge pools . In fact plunge pools are generally formed at the base of water fall due to pounding of rocks by gusting water of the falls. The basaltic bed of the Gaur river near Bhadbhada(east of Jabalpur, M.P)

POT HOLES:

POT HOLES The Glacial pot holes, Shelbern falls

REFERANCE BOOK:

REFERANCE BOOK Geomorphology -Savindra singh www.trekearth.com

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