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Rivers

Most ancient civilizations grew along the banks of rivers. Even today, millions of people all over the world live on the banks of rivers and depend on them for their survival.
All of us have seen a river - large or small, either flowing through our town, or somewhere else. Rivers are nothing more than surface water flowing down from a higher altitude to a lower altitude due to the pull of gravity. One river might have its source in a glacier, another in a spring or a lake. Rivers carry dissolved minerals, organic compounds, small grains of sand, gravel, and other material as they flow downstream. Rivers begin as small streams, which grow wider as smaller streams and rivers join them along their course across theland. Eventually they flow into seas or oceans. Most rivers With the exception of the Nile, flow towards the Equator. The flow in most rivers is not uniform, which means that sometimes there are floods and sometimes no water flows in them. Flood control projects attempt to reduce the variation in flow.

Unfortunately most of the world's major rivers are heavily polluted, but two of the world's largest river systems-the Amazon, that drains a vast area of South America and the Congo in sub-Saharan Africa- remain relatively healthy. This is because both have few industries and a small human population in their watersheds.

Some facts about rivers
The Nile, 6695 km long, and the Amazon 6437 km long, are the world's two longest rivers. Sometimes, measurements of their lengths can vary according to the criteria used for measurement.
An Arab philosopher and physician Avicenna suggested, nearly 1000 years ago, that landscapes changed largely as a result of the action of running water. His views were largely ignored until the 16th century.
The longest river in Asia is the Yangtze, which is 5472 km long.
The world's highest waterfall are the Angel Falls in Venezuela, 979 m high, over 780 m of which is an uninterrupted drop.

Rivers in India
India has a large number of rivers that are lifelines for the millions living along their banks. These rivers can be categorized into four groups:
Rivers that flow down from the Himalayas and are supplied by melting snow and glaciers. This is why these are perennial, that is, they never dry up during the year
The Deccan Plateau rivers, which depend on rainfall for their water
The coastal rivers, especially those on the west coast, which are short and do not retain water throughout the year
The rivers in the inland drainage basin of west Rajasthan, which depend on the rains. These rivers normally drain towards silt lakes or flow into the sand.

The major rivers in India are described here:

Ganga
This is considered the holiest of all the great rivers of India. It has its source at the Gangotri glacier, where it flows from the cave Goumukh, as the Bhagirathi, which then joins the River Alaknanda as it flows towards Devaprayag. The largest tributary of the river is the Ghaghara, which flows from the northern Nepal region and joins it before Patna in Bihar. Another major tributary is the Yamuna originating in the Yamunotri glacier, and flows through Delhi and Agra. Others are the Gomti, Gandak, Son, Kosi, Chambal, Sarda, etc. The Ganga is the lifeline for more than 500 million people living along its banks. The water of the river Ganges is considered so sacred that people keep it in their homes for use in prayers on important occasions such as at the time of death.

Most cities along the river do not have sewage treatment plants and those that do have them can handle only part of the waste water. Millions of tonnes of untreated sewage are dumped daily into the river from the cities that lie along its banks. Bathing and washing also contribute to the pollution as most of the soap that is used is made from chemical substances. The river is also polluted by human and animal faeces. Industrial units that lie along the banks of the river discharge all the waste into the river and only a few of them have proper treatment facilities.

Yamuna
Rising from the Yamunotri glacier in the Tehri Garhwal District in the Himalayas, the Yamuna flows for about 1380 km almost parallel to the Ganga till they meet at Allahabad. It flows through a number of important towns, Delhi, Mathura, Brindaban, and Agra to name some. Since ancient times, the Doab region, where the Ganga and the Yamuna flow, has been considered one of the most fertile areas in the subcontinent. Today however, this majestic river is polluted with domestic waste, silt, and industrial waste. The 22-km stretch between Wazirabad and the Okhla barrage in Delhi is only 2% of the catchment area, but it contributes about 80% of the river's total pollution load. The Hindon Canal also discharges waste from Uttar Pradesh in this stretch. Among the many casualties are birds and fish. There was a time when bird watchers had identified as many as 30 species of birds near the Yamuna, many of them exotic, such as the red-crested pochard and the godwit.

Brahmaputra
This mighty river rises in western Tibet in the Manasarovar region. It flows eastwards through the Himalayas, curves back across Arunachal Pradesh and Assam, then turns south to join the Padma and Ganga in Bangladesh and finally enters the Bay of Bengal. It is known by different names in different regions: as it flows through Tibet it is known as the Tsangpo., In the north-eastern states of Arunachal Pradesh and Assam, it is known as the Siang or Dihang. It is longer and more voluminous than the Ganga, and gushes down with enormous force for most of its course through the mountain regions and the forests of north-east India. A unique feature of this river is that it is navigable even at a height of 10 000 feet.

When compared to the other major rivers in India, the Brahmaputra is less polluted but it has its own problems: petroleum refining units contribute most of the industrial pollution load into the basin along with other medium and small industries. The main problem facing the river basin is that of constant flooding. Floods have been occurring more often in recent years with deforestation, and other human activities being the major causes.

Indus
Known as the Sindhu in ancient times, the Indus was the cradle of India's great Indus Valley civilization. It has its source near Manasarovar close to southwestern Tibet, at an altitude of 16,000 feet and flows westward, through the Himalayas into Ladakh, and then through Sind and Punjab in Pakistan into the Arabian Sea.

After flowing eleven miles beyond Leh, the Indus is joined by its first tributary, the Zanskar. When it enters the plains, its famous five tributaries - the Jhelum, Chenab, Ravi, Beas, and Sutlej - that give Punjab its name (land of the five rivers) join it.

The name India is said to have its roots in Sindhu (Indus), the great river that constitutes the most imposing feature of that part of the subcontinent, home to some of the earliest civilizations.The river Sindhu has been invoked numerous times in the Vedic literature together with those of other gods and goddesses.

Narmada
This is the largest west-flowing river in India and originates from the Mekhala range in Shahdol district, Madhya Pradesh. It flows 1300 km west through the states of Madhya Pradesh and Gujarat before draining into the Gulf of Khambhat in the Arabian Sea. It is said to be one of the most beautiful rivers in India. In terms of its catchment area it is the seventh largest among the fourteen major river basins in the country. It is stated in the Matsya Purana that the mere sight of the river washes away all sins. With many short tributaries flowing into it from north and south, the Narmada basin forms a very important topographic feature of peninsular India.

About 20% of the population along the river lives in the urban areas and the rest in the rural areas: Jabalpur, Hoshangabad, and Khargone in Madhya Pradesh, and Bharuch in Gujarat are some important cities located on the banks.
The major cause of pollution is run-off from agricultural activities yet the pollution level is estimated to be lower than in other major rivers.

Mahanadi
This river is considered the lifeline of Orissa, through which it flows. It originates in south-eastern Madhya Pradesh near Raipur. In the upper drainage basin of the Mahanadi, which is centred on the Chhattisgarh Plain, periodic droughts contrast with the situation in the delta region where floods may damage the crops in what is known as the rice bowl of Orissa. The Hirakud Dam, constructed in the middle reaches of the Mahanadi, has helped in alleviating these adverse effects by creating a reservoir.

Godavari
This river originates in the Sahyadri range to the northeast of Mumbai in Maharashtra. It flows through that state and Andhra Pradesh before entering the Bay of Bengal. Its drainage basin is one of the largest in the country, second in size only to that of the Ganga; its delta on the east coast is also one of the country's main rice-growing areas. Despite the large catchment area the water available is only moderate because of the medium levels of annual rainfall.

Kaveri
The Kaveri is worshipped as a jeeva-nadi or perennial river. It has its origin in Talakaveri in the Kanara district of Karnataka and flows sounthwards through Tamil Nadu and Karnataka.
The waters of the river have been a source of irrigation since antiquity; in the early 1990s, an estimated 95 percent of the Kaveri was diverted for agricultural use before it emptyied into the Bay of Bengal.