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CLASSIFICATION OF RIVERS

(a) ON THE BASIS OF TOPOGRAPHY OF THE RIVER BASIN

(i) Rivers in Hills (Upper Reaches)

(ii) Rivers in Alluvial Plains / Flood Plains (Lower Reaches)

Rivers in Hills: The river generally takes o ro! the !ountains and low through the

hill regions "eore reaching the plains# These upper reaches o the rivers !ay "e

ter!ed as Rivers in Hills# Further they are su"$divided into%

'ncised or Rocky River stage

# oulder River stageRoc! S"a#e or Incise$ River S"a#e % 'n this type* the low channel is generally

or!ed "y the process o degradation# The sedi!ent transported in this reach is oten

dierent ro! the river "ed !aterial* since !ost o it co!es ro! the catch!ents due to

soil erosion#The river reaches are highly steep with swit low and or!ing rapids along

their courses# The "eds and "anks o such rivers are less suscepti"le to erosion#

Bo&l$er River S"a#e + The river "ed in this reaches consists o a !i,ture o "oulders

(rocks with &- inch dia)* gravels and alluvial sand deposits created "y it sel# .uring a

lood the "oulders and gravels are transported downstrea!* "ut as the lood su"sides

the !aterials get deposited in !asses# The water then una"le to shit these heaps* go

round the! and the channel oten wanders in new directions* oten attacking the "anks

and conseuently widening the "ed#

Rivers in All&vial Floo$ Plains: Thechie characteristics o these river reaches is the

0ig$0ag way in which they low* which is called as !eandering# They !eander reely

ro! one "ank to another and carry sedi!ent which is si!ilar to the "ed !aterial# The

!aterials get eroded constantly ro! the concave "ank (outer edge) o the "end and

gets deposited either on the conve, side (inner edge) o the successive "ends or

"etween two successive "ends#

Aggrading

# .egrading

1# 2ta"le3# .eltic

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A##ra$in# or Accre"in# T!'e % i the river is collecting sedi!ent and is "uilding up its

"ed* it is called aggrading or an accreting type river# 't is an silting river which increases

its "ed slope#The silting !ay "e due to heavy sedi!ent load* construction o an

o"struction across the river such as da! or weir* sudden intrusion o sedi!ent ro! a

tri"utary% etc#

e#ra$in# T!'e %' the river "ed is constantly getting scoured to reduce and dissipate

availa"le e,cess land scope* then the river is known as a degrading river#

S"ale T!'e %A river which does not change its align!ent* slope and its regi!e

signiicantly is called as sta"le river# The "ehavior o a particular reach depends !ainly

upon the variations o silt si0e as well as the uantity and low discharge with ti!e#

el"ic Rivers + A river "eore it 4oins the sea* gets

divided into "ranches* thus or!ing a 5 shaped delta#

As the river approaches the sea* its velocity is reduced*

and conseuently the channel gets silted and water

level rises resulting in spills and eventual or!ations o

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new channels# These "ranches !ultiply in their nu!"er as the river approaches the

sea#

Ti$al Rivers+ The tail reaches o the rivers ad4oining the oceans are aected "y the

tides in the ocean# The ocean water enters the river during the lood tide and goes out

into the ocean during e"" tide (The period "etween high tide and low tide during which

water lows away ro! the shore* also called falling tide). These rivers undergo*

periodical rise and all in its water level