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Exogenetic forces -Agents of Degradation (Running water (Rivers)…
Exogenetic forces -Agents of Degradation
Running water (Rivers)
River Basin or Catchment area
- Area drained by a river and its tributaries
Watershed or water divide
- elevated land which separates the catchment area
Different Landforms carved out
1)
V shaped Valley
-In youthful stage river down cuts(Vertical erosion or Valley deepening) it's Valley.e.g. -Indus gorge, shipki la Gorge and dihang Gorge
Gorge
-Very deep and narrow Valley, formed as a result of fast withdrawal of waterfalls
Canyon
- expanded form of gorge, white walls comparatively more vertical e.g. Grand Canyon of Colorado river USA
2)
Waterfalls and rapids
- caused because of sudden descents or abrupt brakes and longitudinal course of river e.g Niagara fall of North America, Victoria fall on zambezi river of Africa.
Rapids
are of lesser height with respect to water falls
3)
Alluvial cones
- When rivers leave the mountains and enter the Plains, their channel gradient drops substantially that results into drop in the load carrying capacity of the river.
As a result Load from upper areas get deposited at the point of break in slope of foothills zone
Collection of Alluvial cones is called Bhabhar region
4)
Alluvial fans
- the load carried by descending river is spread in a vast area that results into formation of fan shaped plains
Combination of Alluvial fans is called foothill Plains or terai region
5)Meanders
- the river stream flow take several turns and form meanders
They are S shaped
Rivers make meanders due to excessive load they carry
Are both erosional and depositional
6)Oxbow lake
- after meander the river gets straighten forming oxbow lake
Formed due to impounding of water in the abandoned meander loops
7)
Levees/Embankment
- Formed due to deposition of the load carried by river as it moves ahead
8)
Floodplains
- when the load carrying capacity of the river gets reduced it starts depositing more and more sediments due to this river water spread into adjoining plains
9)
Delta
- depositional feature formed when the river flows through low lying plains and consequently its load carrying capacity reduces due to decrease in its speed.
Types of delta
Arcuate type
- delta of Nile river, Ganga Brahmaputra delta
Bird food type
- Mississippi- Missouri delta
Estuarine type
- Narmada and Tapi river delta
Cuspate type
- ebro delta in Spain