Ganga basin is a part of the composite Ganga-Brahmputra-Meghna basin. The basin lies in China, Nepal, India and Bangladesh and drains an area of 10,86,000 sq. kms. It is bounded on the north by the Himalayas, on the west by the Aravallis as well as the ridge separating it from Indus basin, on the south by the Vindhyas and Chhotanagpur Plateau and on the east by the Brahmaputra ridge. Its catchment lies in the states of Uttar Pradesh (2,94,364 sq. kms), Madhya Pradesh (1,98,962 sq. kms), Bihar (1,43,961 sq. kms), Rajasthan (1,12,490 sq. kms), West Bengal (71,485 sq. kms), Haryana (34,341 sq. kms), Himachal Pradesh (4,317 sq. kms) and Delhi (1,484 sq. kms). The basin has a population of 356.8 million.
The Ganga originates as Bhagirathi from the Gangotri Glaciers in the Himalayas at an elevation of about 7010-m above mean sea level, in the Uttarkashi district of Uttar Pradesh. The Bhagirathi is joined by the Alaknanda at Deoprayag and the combined stream under the name Ganga flowing through the mountain region debouches into the plains at Rishikesh. It is joined by a large number of tributaries on both the banks in the course of its total run of 2,525 km before its outfall into the Bay of Bengal. The Important tributaries are the Yamuna, the Ramaganga, the Gomti, the Ghagra, the Sone, the Gandak, the Burhi Gandak, the Kosi and the Mahananda. At Farakka in West Bengal the river divides into tow arms namely the Padma which flows to Bangladesh and the Bhagirathi which flows through West Bengal.
The basin comprises mountainous regions of the Himalayan ranges with dense forests, sparsely forested Shivalik hills and the fertile Gangetic plains. The Central highlands lying to the South of the Great plains consist of mountains, hills and plateaus intersected by valleys and river plains. They are largely covered by forests. The important soil types found in the basin are sand, loam, clay and their combinations such as sandy loam, silty clay etc.
The important cities and towns situated on the banks of the Ganga are Haridwar, Kanpur, Allahabad, Varanasi, Patna, Bhagalpur etc. The Ganga has a special place in the psyche of the Indian people as being the most sacred of all Indian rivers. Since time immemorial it has influenced the cultural and religious lives of the Indian people which is eloquently reflected in its awe inspiring references in mythology and folk lore and in being and integral part of various cultural and religious festivals and rituals. Deoprayag, Rishikesh, Haridwar, Garhmuketeshwar, Allahabad and Varanasi are some of the holy places on its banks which attract people from all over the country and abroad.
The annual surface water potential of the basin has been assessed as 525.0 km3. Out of this, 250.0 km3 is utilisable water. Culturable area of the basin is about 58.0 M.ha, which is 29.5% of the total culturable area of the country. Live storage capacity in the basin has increased significantly since independence. From just about 4.2 km3 in the pre-plan period, the total live storage capacity of the completed projects has increased to 37.8 km3. In addition, a substantial storage capacity of over 17.0 km3 would be created on completion of projects under construction. An additional storage to the tune of over 29.6 km3 would become available on the execution of projects under consideration. The hydropower potential of the basin has been assessed as 10,715 MW at 60% load factor.
The Upper Ganga Canal and the Eastern and Western Yamuna Canals built during the nineteenth century, are among the oldest major projects in the basin. Some of the other important projects constructed since independence are Gandhi Sager Dam, Rana Partap Sagar Dam, Narora Barrage, Rajghat Dam, Rihand Dam, Gandak Barrage, Tenughat Dam, Maithon Dam, Kangasabati Dam etc.
Large-scale urbanisation and industrial development brought in its wake the problem of pollution of river water. The Ganga Action Plan taken up in the mid-eighties together with enforcement of various legislative and administrative measures has considerably helped in reducing the pollution of the river especially at Haridwar, Kanpur, Allahabad and Varanasi.
A network of 352 hydrological observation stations is maintained by the Central Water Commission in the basin for various purposes like inflow/flood forecasting, water quality monitoring, assessment of hydrological parameters like discharge, water level, suspended sediment etc.
The water related issues of the basin are both due to high and low flow. Uttar Pradesh, Bihar and West Bengal are the states affected by floods. Many of the flood problems are caused by northern tributaries of Ganga such as Kosi and Mahananda. Besides these problems are also caused by southern tributaries. Ganga Flood Control Commission (GFCC) was setup in 1972 to prepare comprehensive flood control plan & monitoring of flood control projects in the basin.
