- India from the Paleolithic Period to the decline of the Indus civilization
- The development of Indian civilization from c. 1500bce to c. 1200ce
- The early Muslim period
- The Mughal Empire, 1526–1761
- The reign of Akbar the Great
- India and European expansion, c. 1500–1858
- British imperial power, 1858–1947
Drainage into theBay of Bengal
Our editors will review what you’ve submitted and determine whether to revise the article.
News•
TheGanges-Brahmaputra river system
The Ganges and Brahmaputra rivers, together with their tributaries, drain about one-third of India. The Ganges (Ganga), considered sacred by thecountry’s Hindu population, is 1,560 miles (2,510 km) long. Although its deltaic portion lies mostly inBangladesh, the course of the Ganges within India is longer than that of any of the country’s other rivers. It has numerous headstreams that are fed byrunoff and meltwater from Himalayan glaciers and mountain peaks. The main headwater, theBhagirathi River, rises at an elevation of about 10,000 feet (3,000 meters) at the foot of theGangotri Glacier, considered sacred by Hindus.
The Ganges enters theIndo-Gangetic Plain at the city ofHaridwar (Hardwar). From Haridwar toKolkata it is joined by numerous tributaries. Proceeding from west to east, theGhaghara,Gandak, andKosi rivers, all of which emerge from theHimalayas, join the Ganges from the north, while theYamuna andSonare the two most important tributaries from the south. The Yamuna, which also has a Himalayan source (the Yamunotri glacier) and flows roughly parallel to the Ganges throughout its length, receives the flow of several important rivers, including theChambal,Betwa, andKen, which originate in India’s peninsular foreland. Of the northern tributaries of the Ganges, theKosi, India’s most-destructive river (referred to as the “Sorrow of Bihar”), warrants special mention. Because of its large catchment in the Himalayas ofNepal and its gentle gradient once it reaches the plain, the Kosi is unable to discharge the large volume of water it carries at its peak flows, and it frequently floods and changes its course.
The seasonal flows of the Ganges and other rivers fed by meltwaters from the Himalayas vary considerably less than those of the exclusively rain-fed peninsular rivers. That consistency of flowenhances their suitability for irrigation and—where the diversion of water for irrigation is not excessive—for navigation as well.
Although the total length of theBrahmaputra (about 1,800 miles [2,900 km]) exceeds that of the Ganges, only 450 miles (725 km) of its course lies within India. The Brahmaputra, like the Indus, has its source in a trans-Himalayan area about 60 miles (100 km) southeast ofMapam Lake in theTibet Autonomous Region ofChina. The river runs east across Tibet for more than half its total length before cutting into India at the northern border ofArunachal Pradesh state. It then flows south and west through the state ofAssam and south into Bangladesh, where it empties into the vastGanges-Brahmaputra delta. The narrow Brahmaputra basin in Assam is prone to flooding because of its large catchment areas, parts of which experience exceedingly heavy precipitation.
Peninsular rivers
The peninsular drainage into the Bay of Bengal includes a number of major rivers, most notably the Mahanadi, Godavari,Krishna, and Kaveri. Except for the Mahanadi, the headwaters of those rivers are in the high-rainfall zones of theWestern Ghats, and theytraverse the entire width of the plateau (generally from northwest to southeast) before reaching the Bay of Bengal. The Mahanadi has its source at the southern edge of theChhattisgarh Plain.
India’s peninsular rivers have relatively steep gradients and thus rarely give rise to floods of the type that occur in the plains of northern India, despite considerable variations in flow from the dry to wet seasons. The lower courses of a number of those rivers are marked by rapids and gorges, usually as they cross the Eastern Ghats. Because of their steep gradients, rocky underlying terrain, and variable flow regimes, the peninsular rivers are not navigable.
Drainage into theArabian Sea
A substantial part of northwestern India is included in theIndusdrainage basin, which India shares with China,Afghanistan, andPakistan. The Indus and its longest tributary, theSutlej, both rise in the trans-Himalayan region of Tibet. The Indus initially flows to the northwest between towering mountain ranges and throughJammu and Kashmir state before entering the Pakistani-administered portion ofKashmir. It then travels generally to the southwest through Pakistan until it reaches the Arabian Sea. The Sutlej also flows northwest from its source but enters India farther south, at the border ofHimachal Pradesh state. From there it travels west into the Indian state of Punjab and eventually enters Pakistan, where it flows into the Indus.
Between the Indus and the Sutlej lie several other major Indus tributaries. TheJhelum, the northernmost of those rivers, flows out of thePir Panjal Range into theVale of Kashmir and thence viaBaramulaGorge into Pakistani-administered Kashmir. The three others—theChenab,Ravi, andBeas—originate in the Himalayas within Himachal Pradesh. The Chenab travels across Jammu and Kashmir before flowing into Pakistan; theRavi forms a part of the southern boundary between Jammu and Kashmir and Himachal Pradesh states and thereafter a short stretch of the India-Pakistan border prior to entering Pakistan; and theBeas flows entirely within India, joining the Sutlej in the Indian state ofPunjab. The area through which the five Indus tributaries flow has traditionally been called the Punjab (from Persianpanj, “five,” andāb, “water”). That area currently falls in the Indian state ofPunjab (containing the Sutlej and the Beas) and the Pakistani province of Punjab. Despite low rainfall in the Punjab plains, the moderately high runoff from the Himalayas ensures a year-round flow in the Indus and its tributaries, which are extensively utilized for canal irrigation.
Farther to the south, another notable river flowing into the Arabian Sea is theLuni of southernRajasthan, which in most years has carried enough water to reach the GreatRann of Kachchh in westernGujarat. Also flowing through Gujarat is theMahi River, as well as the two most important west-flowing rivers of peninsular India—theNarmada (drainage basin 38,200 square miles [98,900 square km]) andTapi (Tapti; 25,000 square miles [65,000 square km]). The Narmada and its basin have undergone large-scale multipurpose development. Most of the other peninsular rivers draining into the Arabian Sea have short courses, and those that flow westward from headwaters in the Western Ghats have seasonally torrential flows.
Lakes and inland drainage
For such a large country, India has few natural lakes. Most of the lakes in the Himalayas were formed when glaciers either dug out a basin or dammed an area with earth and rocks.Wular Lake in Jammu and Kashmir, by contrast, is the result of a tectonic depression. Although its area fluctuates, Wular Lake is the largest natural freshwater lake in India.
Inland drainage in India is mainlyephemeral and almost entirely in the arid and semiarid part of northwestern India, particularly in theGreat Indian Desert of Rajasthan, where there are several ephemeralsalt lakes—most prominentlySambhar Salt Lake, the largest lake in India. Those lakes are fed by shortintermittent streams, which experience flash floods during occasional intense rains and become dry and lose their identity once the rains are over. The water in the lakes also evaporates and subsequently leaves a layer of white saline soils, from which a considerable amount of salt is commercially produced. Many of India’s largest lakes are reservoirs formed by damming rivers.
Soils
There is a wide range ofsoil types in India. As products of natural environmental processes, they can be broadly divided into two groups: in situ soils and transported soils. The in situ soils get their distinguishing features from the parent rocks, which are sieved by flowing water, sliding glaciers, and drifting wind and are deposited on landforms such as river valleys and coastal plains. The process of sieving such soils has led todeposition of materials in layers without any marked pedologic horizons, though it has altered the original chemicalcomposition of the in situ soils.
Among the in situ soils are the red-to-yellow (including laterite) and black soils known locally asregur. After those the alluvial soil is the third most-common type. Also significant are the desert soils of Rajasthan, the saline soils in Gujarat, southern Rajasthan, and some coastal areas, and the mountain soils of the Himalayas. The type of soil is determined by numerous factors, including climate, relief, elevation, and drainage, as well as by the composition of the underlying rock material.
In situ soils
Red-to-yellow soils
Those soils areencountered over extensive nonalluvial tracts of peninsular India and are made up of such acidic rocks as granite, gneiss, and schist. They develop in areas in which rainfall leaches soluble minerals out of the ground and results in a loss of chemically basic constituents; a corresponding proportional increase in oxidized iron imparts a reddish hue to many such soils. Hence, they are commonly described as ferralitic soils. In extreme cases, the concentration of oxides of iron leads to formation of a hard crust, in which case they are described aslateritic (forlater, the Latin term meaning “brick”) soils. The heavily leached red-to-yellow soils are concentrated in the high-rainfall areas of the Western Ghats, the westernKathiawar Peninsula, eastern Rajasthan, the Eastern Ghats, theChota Nagpur plateau region, and other upland tracts of northeastern India. Less-leached red-to-yellow soils occur in areas of low rainfall immediately east of the Western Ghats in the dry interior of theDeccan. Red-to-yellow soils are usually infertile, but that problem is partlyameliorated in forested tracts, where humus concentration and the recycling of nutrients help restore fertility in the topsoil.