Drainage Test - 1

The Ganga river has the largest drainage basin in India. The total length of the Ganga River from its source to its mouth (measured along the Hugli) is 2525 km, of which 310 km in Uttaranchal, 1,140 km in Uttar Pradesh, 445 km in Bihar and 520 km in West Bengal. The remaining 110 km stretch of the Ganga forms the boundary between Uttar Pradesh and Bihar. The river flows majestically from Gangotri to Bay of Bengal with an average gradient of 9.5 cm per km.

The Ganga is joined by many tributaries from the Himalayas. These are the Yamuna, the Ghaghara, the Gandak and the Kosi. The river Yamuna flows parallel to the Ganga and as a right bank tributary, meets the Ganga at Allahabad. The Ghaghara, the Gandak and the Kosi rise in the Nepal Himalayas. The main tributaries which come from the peninsular uplands are the Chambal, the Betwa and the Son.

Dendritic pattern - A dendritic drainage pattern is the most common form and looks like the branching pattern of tree roots. It develops in regions underlain by homogeneous material. That is, the subsurface geology has a similar resistance to weathering so there is no apparent control over the direction the tributaries take.
Trellis pattern - A drainage pattern in which tributaries join at high angles, often approaching right angles, which is common in areas with rocks of different strengths (thus resistance to erosion) and in areas with regular series of folds (anticlines and synclines).
Radial pattern - A drainage pattern in which consequent streams radiate or diverge outward, like the spokes of a wheel, from a high central area; it is best developed on the slopes of a young, unbreached domal structure or of a volcanic cone.
Rectangular drainage develops on rocks that are of approximately uniform resistance to erosion, but which have two directions of jointing at approximately right angles or 90 degrees.

The rivers which have their sources near the lake Mansarovar in Tibet are Indus, Satluj and Brahmaputra.
The Indus River originates near Manasarovar Lake from Mount Kailash of China. It flows through Leh in India and later through Pakistan before emptying into the Arabian Sea.
The Satluj originates in the vicinity of Lake Mansarovar - Mount Kailash peak on the Tibetan plateau, as does the Brahmaputra, and enters Himachal at an altitude of 3,000 metres and flows out from Bhakra Dam at about 500 metres.
The Jhelum River is a river in northern India and eastern Pakistan. It is the westernmost of the five rivers of the Punjab region, and passes through the Kashmir Valley. It is a tributary of the Chenab River and has a total length of about 725 kilometres.

The Indus Waters Treaty signed between India and Pakistan in 1960 allows India to use only 20 percent of the six-river Indus water system. The World Bank-brokered water sharing agreement gives control over the three eastern rivers, Beas, Ravi and Sutlej to India, and the three western rivers, Indus, Chenab and Jhelum to Pakistan. This water is used for irrigation in Punjab, Haryana and the Southern and Western parts of Rajasthan.

River Narmada is the main river that originates from the Central Highlands and flows towards the West that is in the regions of Rajasthan and Gujarat. After descending towards the south, it consequently mixes with the Arabian Sea same as in the case of River Ganga which drifts towards Bay of Bengal. The Tapti River is also a river in central India between the Godavari and Narmada rivers which flows westwards before draining into the Arabian Sea.

The Western Ghats form one of the four watersheds of India, feeding the perennial rivers of India. The major river systems originating in the Western Ghats are the Godavari, Kaveri, Krishna, Thamiraparani and Tungabhadra rivers. The majority of streams draining the Western Ghats join these rivers, and carry a large volume of water during the monsoon months. These rivers flow to the east due to the gradient of the land and drain out into the Bay of Bengal. Major tributaries include the Bhadra, Bhavani, Bhima, Malaprabha, Ghataprabha, Hemavathi and Kabini rivers. The Periyar, Bharathappuzha, Pamba, Pranhita, Sabarmati, Kali, Mandovi and Zuari rivers flow westwards towards the Western Ghats, draining into the Arabian Sea, and are fast-moving, owing to the steeper gradient.

The Godavari is the second longest river in India after the river Ganga. The Godavari originates in the Western Ghats near Nasik in Maharashtra. Major tributaries of the river include the Purna (South), Pravara, Indravati, Manjira River, Bindusara River, Sabari River, Wainganga, and Wardha River. Bharathpuzha, also known as the Nila, is a river in India in the state of Kerala. With a length of 209 km, it is the second longest river in Kerala after the Periyar. Nila has groomed the culture and life of South Malabar part of Kerala. It is not a tributary of Godavari.

The Krishna River is the fourth-biggest river in terms of water inflows and river basin area in India, after the Ganga, Godavari and Brahmaputra. The principal tributaries joining Krishna are the Ghataprabha River, Malaprabha River, Bhima River, Tungabhadra River, Koyana and Musi River. Most of this basin comprises rolling and undulating country, except for the western border, which is formed by an unbroken line of the Western Ghats.

Wular Lake is one of the largest fresh water lakes in Asia. It is sited in Bandipora district in Jammu and Kashmir, India. The lake basin was formed as a result of tectonic activity and is fed by the Jhelum River. The lake's size varies seasonally from 12 to 100 square miles (30 to 260 square kilometres). In addition, much of the lake has been drained as a result of willow plantations being built on the shore in the 1950s.

The Sambhar Salt Lake, India's largest inland salt lake, is located 80 km southwest of the city of Jaipur and 64 km northeast of Ajmer, Rajasthan. It surrounds the historical Sambhar Lake Town. The lake receives water from five rivers: Medtha, Samaod, Mantha, Rupangarh, Khari, and Khandela. Lake has 5700 square km catchment area. The lake is an extensive saline wetland, with water depth fluctuating from as few as 60 centimetres (24 in) during the dry season to about 3 meters (10 ft) at the end of the monsoon season. It occupies an area of 190 to 230 square kilometers based on the season.

The Zaskar, the Nubra, the Shyok and the Hunza are the tributaries which join Indus River in the Kashmir region. The Zaskar Range is a mountain range in the Indian regions of Jammu and Kashmir and Ladakh, which separates Zanskar from Ladakh. Nubra is a subdivision and a tehsil in the Indian union territory of Ladakh. Its inhabited areas form a tri-armed valley cut by the Nubra and Shyok rivers. Hunza River is the principal river of Hunza in Gilgit–Baltistan, Pakistan. It is formed by the confluence of the Chapursan and Khunjerab nalas which are fed by glaciers. It is joined by the Gilgit River and the Naltar River before it flows into the Indus River.

The Central Government started the river pollution abatement programme with the launching of the Ganga Action Plan (GAP-I) in the year 1985. Subsequently, the GAP Phase II was launched in 1993 for pollution abatement of river Yamuna and Gomti, major tributaries of river Ganga. The river pollution abatement programme was further expanded to include other major rivers of the country in 1995 under the aegis of National River Conservation Plan (NRCP). Finally in December 1996, GAP Phase II was also merged with the NRCP and all projects for river cleaning in the country were brought under one umbrella scheme of NRCP. The objective of NRCP is to reduce the pollution load in rivers through implementation of various pollution abatement works, thereby improving their water quality.

The expanded NRCP now covers 152 towns located along 27 interstate rivers in 16 states. Under this action plan, pollution abatement works were taken up in 57 towns. A total of 215 schemes of pollution abatement were sanctioned. So far, 69 schemes have been completed under this action plan. A million litres of sewage is targeted to be intercepted, diverted and treated.

Most lakes have at least one natural outflow in the form of a river or stream, which maintain a lake's average level by allowing the drainage of excess water. Some lakes do not have a natural outflow and lose water solely by evaporation or underground seepage or both. They are termed endorheic lakes. Gobind Sagar Lake is a Reservoir situated in Una and Bilaspur districts of Himachal Pradesh. It is formed by the Bhakra Dam. The Reservoirs is on the River Sutlej and is named in honour of Guru Gobind Singh, the tenth Sikh guru.

Kolleru Lake, also called Colair Lake, is located in northeastern Andhra Pradesh state, southern India. It lies between the Godavari and Krishna river deltas near the city of Eluru. During the height of the summer monsoon rainy season, the lake may expand to 100 square miles (260 square km). Carp and prawns are fished commercially in the lake, and prawns are processed at the village of Akid.