Dendritic Pattern

Meander:
(i) A meander is formed when the moving water in a stream erodes the outer banks and widens its valley and the inner part od the river has less energy and deposits what it is carrying.
(ii) In general , it is a bend in a sinuous watercourse or river.

In Arunachal Pradesh through a gorge.

Dendritic

The Himalayan River Systems
(i) Major Himalayan rivers are the Indus, the Ganga and the Brahmaputra.
(ii) Because of their length, long distance flow, and numerous large and important tributaries; they may be called river systems.

(i)  The Indus river system
(ii) The Ganga river system
(iii)The Brahmaputra river system.

Two Peninsular rivers flowing in troughs:
(a)Narmada
(b)Tapi(Tapti)

Two headstreams of Ganga:
(a) Bhagirathi.From Gangotri glacier.
(b) Alakananda.From uplands beyond Devaprayag
They both converege as Ganga at Devaprayag.

Origin of the Indus and the Ganga:
(a) Indus: Near Kailash mountains,Mansarovar lake.
(b) Ganga: G0-mukh/Gangotri Glacier(Ganga originates from this glacier as Bhagirathi)

A water divide means the upland which divides the two drainage basins from each other.
Example: Ambala-Saharnpur upland seperates the Indus Basin from the Ganga Basin

(i) Due to growing population, rapid industrialisation  and urbanisation , more and more water is being drained out of rivers. This reduces river volume.
(ii) A heavy load of untreated sewage and industrial effluents are emptied into the rivers. Thus the water of the rivers become polluted .
(iii) Human ashes, dead animals and birds thrown into the rivers, also pollute the river waters.
Methods of controlling Water Pollution
(i) The waste  products from the factories should not be treated before flowing into rivers.
(ii) The waste material should be treated before flowing into rivers.
(iii) Sewage of urban centres should not be allowed into rivers.

The rivers are important in country's economy because of the following reasons:
1. Because of the rivers being more than water carrying channels,human civilisations,had flourished and developed in the river valleys.
2. Besides water,they carry sediments and minerals which are very useful for us.
3. Rivers sustained all types of human activities like hunting,gathering,pastoral and farming activities by providing them wastes
4. They help cities and towns by carrying their sewage wastes.
5. Rivers provide cheap and efficient inland transport for trade and commerce.
6. Their waste is extensively used in irrigation and in developing hydroelectricity.
7. They also provide water to reservoris are used for fishing and recreational activities.

Economic Benefits of Rivers and Lakes
(a) Rivers and lakes provided water to humans as a basic natural resources.Water is essential for human,agriculture and industries activities
(b) Rivers and their alluvial soil provide agriculture lands.
(c) Water of the rivers is taken to agriculture fields through canals for irrigation of agriculture crops.It helps to fight the vagaries of the monsoon rains.
(d) River water is stored in big lakes by damming them and is used for generation of hydroelectricity
(e) They also carry city wastes
(f) Rivers provide recreational facilities

Drainage System in India:
Indian river systems are grouped into two main classes. They .are:
(i) The Himalayan rivers and
(ii) The Peninsular rivers.
(A) Himalayan rivers originate from the Himalayan mountains and the Peninsular rivers from the plateau. Hence, the Himalayan and the Peninsular rivers are different from each other. 
(i) The Himalayan rivers are mostly perennial.
(ii) They originate from the north of the mountain ranges.
(iii) They have cut through the mountains making spectacular gorges, due to the upliftment of the mountains and down cutting of rivers simultaneously.
(iv) They perform intensive erosional activities upstream and carry large am of load of sand and silt.
(v) The courses of the Himalayan rivers are very long from their source to the sea.
(vi) Himalayan rivers have large basins.
(vii) In plains they flow forming large meanders due to gentle scope.
(viii) They form numerous depositional features like flood plain, river bluffs and levees.
(ix) They have formed well-developed deltas.
(B) Peninsular rivers are seasonal, because their flow is dependant on rainfall.
(i) During the dry season, even the large rivers have a highly reduced flow of water in their channels.
(ii) These rivers have shorter and shallower courses as compared to their Himalayan counterparts.
(iii) Some of them originate in the Eastern Ghats and flow towards the west. But most of the rivers originate in the Western Gl'mts and flow towards the Bay of Bengal.