Long Question Answers: Drainage System | Geography Class 11 - Humanities/Arts PDF Download

Q. 1. Distinguish between East flowing and West flowing rivers of the Peninsular India.
Ans. East flowing Rivers
1. The Mahanadi, Godawari, Krishna, Cauvery are east flowing rivers.
2. These rivers form deltas on the east coast.
3. These rivers fall into Bay of Bengal.
West flowing Rivers
1. The Narmada and Tapti are west flowing rivers.
2. These rivers do not form deltas on the west coast.
3. These rivers fall into Arabian sea.

Q. 2. Distinguish between antecedent drainage and consequent drainage.
Ans. Antecedent Drainage
1. These rivers maintain their original slope (before the up-lift), despite the rise of the land due to folding.Rivers keep on flowing in the original direction.
2. These rivers are older than the fold mountains over which these rivers flow.
3. These rivers cut deep gorges due to down cutting.
4. The trans Himalayan rivers Indus, Sutlej, Kosi, represent antecedent rivers.
Consequent Drainage
1. In an up-lifted area, the rivers flow in the direction resulting as a consequence of the slope.
2. These rivers are formed after the uplift of the area.
3. These rivers do not form gorges.
4.  The rivers of the Peninsular India flow eastward, according to slope, and are consequent rivers.

Q. 3. Bring out clearly the differences in the drainage features and hydrological characteristics between the Himalayan Rivers and Peninsular Rivers.
Ans. River systems of India can be classified, on the basis of their origin in two categories:
(a) The Himalayan River System. Indus, Ganga and Brahmputra are the three main rivers.
(b) The Peninsular River System. Mahanadi, Godavari and Cauvery are the three main rivers.
Himalayan River System:-
1. Catchment. The Himalayan rivers have large basins. Their catchment area covers extensive areas. The Indus has a catchment area of 10.63 lakh sq. kms., while the Ganga has a catchment of about 8 lakh sq. kms.
2. Terrain. The trans Himalayan rivers pass through deep gorges before entering the plains. Among the high fold mountains, these perform rapid erosion. These rivers have a mean-dering course on plains.
3. Flow pattern. TheHimalayan rivers are perennial. They get water flow from melting of snow and rainfall.
4. Length. TheHimalayan rivers are long. The Indus is 2880 kms. long and the Ganga is 2525 kms. long.
5. Number. There are many rivers rising from the Himalayas.
6. Most of the Himalayan rivers are antecedent rivers.
7. Most of the Himalayan rivers are useful for irrigation and navigation.
Peninsular River System:-
1. The peninsular rivers have a small catchment area. The Godavari basin extends over 3 lakh sq. kms. while Mahanadi has a catchment area of about 1.4 lakh sq. kms.
2. Peninsular rivers flow through graded, shallow river valleys. These flow over nonalluvial hard beds. The rivers have straight courses, the meanders are almost absent.
3. The Peninsular rivers are seasonal. These get supply of water from rain received during summer monsoons.
4. The Peninsular rivers are not so long. Godavari (1465 kms.), the Krishna (1400 kms.) are the main rivers.
5. There are not many rivers in the peninsular India.
6. Most of the peninsular rivers are consequent rivers.
7. Peninsular rivers are not useful for irrigation and navigation.

Q. 4. Describe the usability of rivers of India.
Ans. USABILITY OF RIVERS:- The great rivers comprise large water wealth of the country. The volume of annual precipitation in the country is estimated at about 37,00,400 million cubic metres. A large part of it seeps into the ground and some part is lost by evaporation and transpiration. The rivers carry about 16,77,532 million cubic metres of water per year. For uneven topography and flow characteristics, all of this not usable. About 5,55,166 million cubic metres of river water - 33 per cent of the annual flow, are usable for irrigation.
Large rivers have great water power potential. The Himalayas in the north, the Vindhyas, the Satpura and the Aravalli in the west, the Maikala and Chhotanagpur in the east, the Meghalaya plateau and Purvanchal in the north-east, and the Western and the Eastern Ghats of the Deccan plateaus offer possibilities of large scale water power development.
Sixty per cent of the total river flow is concentrated in the Himalayan rivers, 16 per cent in the Central Indian rivers (the Narmada, the Tapi, the Mahanadi, etc.), and the rest in the rivers of the Deccan plateaus.
Dependable power generation from the peninsular rivers requires impounding of water during the monsoon months. The Himalayan rivers do not have such problems as their flow is appreciable even during the critical winter months. They, however, have other kind of problems, namely, difficulty in construction of large storage on account of narrow valleys, high seismicity of the region and vast alluvial plain with no variation in relief. The country has an exploitable power potential of about 41 million kw at 60 per cent load factor from these rivers.
The Ganga and the Brahmaputra in the north and northeastern part of the country, the Mahanadi in Odisha, the Godavari and the Krishna in Andhra, the Narmada and the Tapi in Gujarat, and the lakes and tidal creeks in coastal states possess some of the important and useful water ways of the country. In the past they were of great importance,  which suffered with the advent of rail and roads. Withdrawal of large quantities of water for irrigation resulted in dwindling flow of many rivers. The country has a navigable water ways of about 10,600 km — 2480 km of navigable rivers by steamers and large country boats, 3920 km of navigable rivers by medium sized country boats, and 4200 km of canals and back waters navigable by country boats. The most important navigable rivers are the Ganga the Brahmaputra and the Mahanadi. The Godavari, the Krishna, the Narmada and the Tapi are navigable near their mouths only. The rivers also supply water to cities, villages and big industrial installations.

Q. 5. Prove that the three major rivers of India (Indus, Sutlej and Brahmaputra) existed long before the Himalayas came into being.
Ans. The Indus, Sutlej, and Brahmaputra are trans-Himalayan rivers. These originate beyond the great Himalayas in the region surrounding Kailash and Mansarover in Tibet. These flow parallel to the Himalayas for a long distance and enter the northern plains after cutting deep gorges or canyons (I-shaped valleys). These gorges have vertical walls on either sides. While the Himalayas have been rising, these rivers have been deepening the velleys. In Arunachal Pradesh, the Himalayas have rises to a height of 7,757 metres (Namcha Barwa), but the river has cut deep Dihang Gorge (5,500 metres deep). The result is that the gorge is about 13000 metres deep, It shows that these rivers existed already in the form of Antecedant Drainage.

Q. 6. Write a note on National River Conservation Plan (NRCP) an Ganga Action Plan (GAP).
Ans. The activities of Ganga Action Plan (GAP) Phase-I, initiated in 1985, were declared closed on 31st March 2000. The steering Committee of the National River Conservation Authority reviewed the progress of the GAP and necessary correction of the basis of leassons learnt and experiences gained from GAP PhaseI. These have been applied to the major polluted rivers of the country under the NRCP.
The Ganga Action Plan (GAP) Phase-II, has been merged with the NRCP. The expanded NRCP now covers 152 towns located along 27 interstate rivers in 16 states. Under this action plan, pollution abatement works are being taken up in 57 towns. A total of 215 schemes of pollution abatement have been sanctioned.
So far, 69 schemes have completed under this action plan. A million litre of sewage is targeted to be intercepted diverted and treated.