Social Science 4 Marks Each

(1) A confluence takes place of the rivers Alaknanda and Bhagirathi originating near Gangotri in Himalayas near Devprayag. From there onward their combined flow is known as 'Ganga'. It enters the plains near Haridwar.
(2) In the plain region, many small and large rivers come from north and meet Ganga. Ghaghra, Gandak and Kosi coming from Nepal are main rivers of them.
(3) River Yamuna originates from Yamunotri in the Himalayas. The confluence between Ganga and Yamuna takes place near Prayag (Allahabad) on the right bank of Ganga and between Ganga and Son (Shon) near Patna.
(4) Ganga bifurcates into two branches near Parakka in West Bengal. Its main branch flows further in south-east, enters Bangladesh under the name 'Padma'. Second branch in the south flows under the name 'Bhagirathi-Hugli' and meets the Bay of Bengal.
(5) Padma merges with Brahmaputra in Bangladesh where it is called 'Jamuna'. Its combined flow thereafter is known as 'Meghna' till the Bay of Bengal.
(6) Ganga is more than 2500 km long, It has the largest basin area in India. Most of the water of North India flows out in the Bay of Bengal through the Ganga River System.
(7) The Ganga-Brahmaputra delta is very much fertile. It is called as 'Sundarvan'.

(1) There are many small and large lakes in India. (2) Fresh water lakes are found mostly in the Himalayan region. These are formed due to glaciers. On mountain slopes, depressions are filled in with snow which melts due to the heat, water remains stagnant in the depression and forms a lake. (3) Wular Lake of Kashmir is formed due to tectonic movements. It is the largest fresh water lake of India. (4) Dal Lake of Srinagar, Bhimtal, Nainital, Loktal, Badapani, etc. are also important fresh water lakes (5) Due to flood hazards. Ox-bow lakes are formed in the river meanders. (6) Tides have resulted Into the formation of 'lagoons'. (7) Chilka Lake of Odisha. Pulicat Lake of Coromandel coast and Vembanad Lake of Malabar coast are large saline water 'Lagoons' (backwaters). Of them, Chilka is the largest lake. It is also the largest natural lake of India. (8) Sambhar is a saline water lake. Salt is produced from this lake. (9) Many man-made lakes in India are created due to the construction of dams across the rivers.

(1) Brahmaputra originates near Mansarovar, the place of origin of Sindhu and Satluj in Tibet. It is slightly longer than Sindhu but a large part of her flow is beyond India.
(2) In Tibet, it flows eastward parallel to Himalaya and after taking a 'U' turn around Namcha Barwa peak (7757 m) enters Arunachal Pradesh. Here it has carved out a 5500 metres deep gorge. In India it flows through Arunachal Pradesh and Assam. Many rivers with ample water meet her here.
(3) This river is known as "Tsangpo' in Tibet, as 'Dihang' or 'Sitang' in Arunachal Pradesh. as 'Brahmaputra' in Assam and as 'Jamuna' in Bangladesh.
(4) There is less of water and sediments in Tsang Po in Tibet, but it flows through a region of heavy rainfall of Assam, so there is huge addition of water and sediments. Moreover, water from many tributaries is emptied into this river.
(5) In Assam, Brahmaputra flows in a braided form, divided among many tributaries connected with each other. That is why there are few large islands within its course.
(6) Every year, there is a large increase in volume of water in Brahmaputra during rainy season. As a result, there are frequent floods in the river and there is heavy devastation in Assam and Bangladesh.