Grade 12 geomorphology notes

Geomorphology:
Drainage basin concepts: * watershed vs.

interfluve




IT
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I




winfiltration

Base flow :
underground
>
water that seeps

back into rivers

,FACTORS INFLUENCING HOW MUCH WATER ENTERS THE

DRAINAGE SYSTEM :




vegetation
-




-

soil type
-

Rainfall
-
land use

-

Rock type
-



Relief


TYPES OF RIVERS :
pony rainy permanent




:÷÷:":
episodic
river ↳ all
↳ storms year


wet season



is
high


dry season

i. lower water

table

exotic
↳ river in desserts
↳ supplied with water

from where
they begin

, TYPES OF DRAINAGE PATTERNS :
( vertical profile )


①
↳
DENDRITIC

tree like branches
:


µ
↳ joins at acute angles
rocks with uniform
↳
sedimentary resistance




② RECTANGULAR :




river has 90° tributaries
↳ main
angles join at 90
.




,



↳
underlying rock structure is jointed igneous rock




③ TRELLIS :



90 the tributaries
-




↳ main stream is parallel and to

hard
↳
Underlying rock folded rocks with alternate

and soft rocks



PARALLEL :




↳ caused
by steep slopes
↳ few tributaries
in same direction
↳ flow
↳ uniform resistance


④ DERRANGED :




↳ small streams with no specific pattern
↳ flat areas

↳ often cause lakes / dams to form




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