Indus River -- Britannica Online Encyclopedia

10/12/2017 Indus River -- Britannica Online Encyclopedia

Indus River

Indus River, Tibetan and Sanskrit Sindhu, Sindhi Sindhu, or Mehran, great trans-Himalayan river of South Asia. It is one of TABLE OF CONTENTS the longest rivers in the world, with a length of some 2,000 Introduction miles (3,200 km). Its total drainage area is about 450,000 square miles (1,165,000 square km), of which 175,000 square Physical features miles (453,000 square km) lie in the ranges and foothills of the People Himalayas, the Hindu Kush, and the Karakoram Range; the rest Economy is in the semiarid plains of Pakistan. The river’s annual �ow is about 58 cubic miles (243 cubic km)—twice that of the Nile River and three times that of the Tigris and Euphrates rivers combined. The river’s conventional name derives from the Tibetan and Sanskrit name Sindhu. The earliest chronicles and hymns of the Aryan peoples of ancient India, the Rigveda, composed about 1500 BCE, mention the river, which is the source of the country’s name.

PHYSICAL FEATURES

The river rises in the southwestern Tibet Autonomous Region of China near Lake Mapam at an elevation of about 18,000 feet (5,500 metres). For about 200 miles (320 km) it �ows northwest, crossing the southeastern boundary of the disputed Kashmir region at about 15,000 feet (4,600 metres). A short way beyond Leh, in Ladakh (in the Indian-administered state of Jammu and Kashmir), it is joined on its left by its �rst major tributary, the Zaskar River. Continuing for 150 miles (240 km) in the same direction into the Pakistani-administered areas of the Kashmir region, the Indus is joined by its notable tributary the Shyok River on the right bank. Below its con�uence with the Shyok, as far as the Kohistan region of Pakistan’s Khyber Pakhtunkhwa province, it is fed by mighty glaciers on the slopes of the Karakoram Range, the Nanga Parbat massif, and the Kohistan highlands. The Shyok, Shigar, Gilgit, and other streams carry glacial meltwater into the Indus.

The Shigar River joins the Indus on the right bank near Skardu in Baltistan. Farther downstream the Gilgit River is another right-bank tributary, joining it at Bunji. A short distance downstream the Astor River, running off the eastern slope of Nanga Parbat, joins as a left-bank tributary. The Indus then �ows west and turns south and southwest to enter Khyber Pakhtunkhwa province, in the process skirting around the northern and western sides of the Nanga Parbat massif (26,660 feet [8,126 metres]) in gorges that reach depths of 15,000 to 17,000 feet (4,600 to 5,200 metres) and widths of 12 to 16 miles (19 to 26 km). Trails cling grimly to precipitous slopes overlooking the river from elevations of 4,000 to 5,000 feet (1,200 to 1,500 metres).

https://www.britannica.com/print/article/286872 1/9 10/12/2017 Indus River -- Britannica Online Encyclopedia After emerging from this highland region, the Indus �ows as a rapid mountain stream between the Swat River and Hazara areas in Khyber Pakhtunkhwa province until it reaches the reservoir of Tarbela Dam. The Kābul River joins the Indus just above Attock, where the Indus �ows at an elevation of 2,000 feet (600 metres) and is crossed by the �rst bridge carrying rail and road. Finally, it cuts across the Salt Range near Kalabagh to enter the Punjab Plain.

The Indus receives its most-notable tributaries from the eastern Punjab Plain. These �ve rivers— the Jhelum, Chenab, Ravi, Beas, and Sutlej—give the name Punjab (“Five Rivers”) to the region divided between Pakistan and India.

After receiving the waters of the Punjab rivers, the Indus becomes much larger, and during the �ood season (July to September) it is several miles wide. It �ows through the plain in western and southern Punjab province in Pakistan at an elevation of about 260 feet (80 metres). Because it moves so slowly across the plain, it deposits accumulated silt on its bed, which is thus raised above the level of the Pakistanis taking shelter on higher ground sandy plain; indeed, most of the plain in Sindh (Sind) after an Indus River flood, near Thatta, Sindh province, … province in Pakistan has been built up by alluvium laid down by the Indus. Embankments have been constructed Kevin Frayer/AP to prevent �ooding, but occasionally these give way, and �oods destroy large areas. Such �oods occurred in 1947, 1958, and 2010. During heavy �ooding the river sometimes changes its course.

Near Tatta the Indus branches into distributaries that form a delta and join the sea at various points south-southeast of Karachi. The delta covers an area of 3,000 square miles (7,800 square km) or more (and extends along the coast for about 130 miles (210 km). The uneven surface of the delta contains a network of existing and abandoned channels. The coastal strip, from about 5 to 20 miles (8 to 32 km) inland, is �ooded by high tides. The Indus delta has elongated protruding distributaries and low sandy beaches.

HYDROLOGY

The principal rivers of the Indus River system are snow-fed. Their �ow varies greatly at different times of the year: the discharge is at a minimum during the winter months (December to February), there is a rise of water in spring and early summer (March to June), and �oods occur in the rainy season (July to September). Occasionally, there are devastating �ash �oods. The Indus and its tributaries receive all their waters in the hilly upper parts of their catchments. Therefore, their �ow is at a maximum where they emerge out of the foothills, and little surface �ow is added in the plains, where evaporation and seepage considerably reduce the �ow volume. On the other hand, some water is added by seepage in the period after the monsoon https://www.britannica.com/print/article/286872 2/9 10/12/2017 Indus River -- Britannica Online Encyclopedia 10/12/2017 Indus River -- Britannica Online Encyclopedia After emerging from this highland region, the Indus �ows as a rapid mountain stream months. In the main stream of the Indus, the water level is between the Swat River and Hazara areas in Khyber Pakhtunkhwa province until it reaches the at its lowest from mid-December to mid-February. After reservoir of Tarbela Dam. The Kābul River joins the Indus just above Attock, where the Indus that the river starts rising, slowly at �rst and then more �ows at an elevation of 2,000 feet (600 metres) and is crossed by the �rst bridge carrying rail rapidly at the end of March. The high-water level usually and road. Finally, it cuts across the Salt Range near Kalabagh to enter the Punjab Plain. occurs between mid-July and mid-August. The river then falls rapidly until the beginning of October, when the The Indus receives its most-notable tributaries from the eastern Punjab Plain. These �ve rivers— water level subsides more gradually. Annually, the upper the Jhelum, Chenab, Ravi, Beas, and Sutlej—give the name Punjab (“Five Rivers”) to the region Indus carries about 26.5 cubic miles (110 cubic km)— divided between Pakistan and India. slightly less than half the total supply of water in the Indus After receiving the waters of the Punjab rivers, the Indus River system. The Jhelum and Chenab combined carry becomes much larger, and during the �ood season (July The upper Indus River in the Himalayas. roughly one-fourth, and the Ravi, Beas, and Sutlej to September) it is several miles wide. It �ows through the © Ric Ergenbright/Corbis combined constitute the remainder of the total supply of plain in western and southern Punjab province in Pakistan the system. at an elevation of about 260 feet (80 metres). Because it There is considerable physiographic and historical evidence to prove that since the dawn of moves so slowly across the plain, it deposits accumulated civilization—at least since the days of the Indus civilization, some 4,500 years ago—the Indus, silt on its bed, which is thus raised above the level of the Pakistanis taking shelter on higher ground from southern Punjab province to the sea, has been shifting its course. It is con�ned between sandy plain; indeed, most of the plain in Sindh (Sind) after an Indus River flood, near Thatta, limestone ridges at Rohri in Sindh, but thereafter it has wandered, shifting generally to the Sindh province, … province in Pakistan has been built up by alluvium laid west, particularly in its delta. In northern Sindh the Indus has shifted westward a distance of down by the Indus. Embankments have been constructed Kevin Frayer/AP about 10 to 20 miles (16 to 32 km) in the last seven centuries. The river is now held back to to prevent �ooding, but occasionally these give way, and some extent by higher ground from Sehwan to Thatta at the head of the delta, but the �oods destroy large areas. Such �oods occurred in 1947, 1958, and 2010. During heavy �ooding possibility of future shifting cannot be ruled out. There is also evidence of the shifting of the the river sometimes changes its course. Chenab, Ravi, Beas, and Sutlej rivers during the historical period. Near Tatta the Indus branches into distributaries that form a delta and join the sea at various points south-southeast of Karachi. The delta covers an area of 3,000 square miles (7,800 CLIMATE square km) or more (and extends along the coast for about 130 miles (210 km). The uneven From its source to its mouth, the annual precipitation in the Indus region varies between 5 and surface of the delta contains a network of existing and abandoned channels. The coastal strip, 20 inches (125 and 510 mm). Except for the mountainous section of Pakistan, the Indus valley from about 5 to 20 miles (8 to 32 km) inland, is �ooded by high tides. The Indus delta has lies in the driest part of the subcontinent. Northwestern winds sweep the upper Indus valley in elongated protruding distributaries and low sandy beaches. winter and bring 4 to 8 inches (100 to 200 mm) of rainfall—vital for the successful growing of HYDROLOGY wheat and barley. The mountainous region of the upper Indus receives precipitation largely in the form of snow. A large amount of the Indus’s water is provided by melting snows and The principal rivers of the Indus River system are snow-fed. Their �ow varies greatly at different glaciers of the Karakoram, Hindu Kush, and Himalayan ranges. The monsoon rains (July to times of the year: the discharge is at a minimum during the winter months (December to September) provide the rest of the �ow. The climate of the Indus valley ranges from that of the February), there is a rise of water in spring and early summer (March to June), and �oods occur dry semidesert areas of Sindh and Punjab provinces to the severe high mountain climate of in the rainy season (July to September). Occasionally, there are devastating �ash �oods. The Kohistan, Hunza, Gilgit, Ladakh, and western Tibet. January temperatures average below Indus and its tributaries receive all their waters in the hilly upper parts of their catchments. freezing in the mountainous north, while July daytime high temperatures average about 100 °F Therefore, their �ow is at a maximum where they emerge out of the foothills, and little surface (38 °C) in Sindh and Punjab provinces. Jacobabad, one of the hottest spots on Earth, is situated �ow is added in the plains, where evaporation and seepage considerably reduce the �ow west of the Indus River in northern Sindh and often records summer maximums of 120 °F (49 volume. On the other hand, some water is added by seepage in the period after the monsoon °C). https://www.britannica.com/print/article/286872 2/9 https://www.britannica.com/print/article/286872 3/9 10/12/2017 Indus River -- Britannica Online Encyclopedia PLANT AND ANIMAL LIFE

There is a close relationship between climate and vegetation in the Indus valley. In Sindh province on the lower Indus, desert conditions prevail 10 to 25 miles (15 to 40 km) away from the river, and the area is dominated by sand and poor grass cover. Irrigation by �oods or canals permits some cultivation, although intensive irrigation often produces soil salinization. In northern Sindh and in Punjab province, overgrazing and felling timber for fuel have destroyed much of the natural vegetation. Further, prolonged human interference with natural drainage and deforestation in the Himalayan foothills have led to a drop in groundwater levels and a further loss of vegetation. It appears that in prehistoric and earlier historic times the middle Indus region was more wooded than it is at present: accounts of Alexander the Great’s Indian campaigns (c. 325 BCE) and records of Mughal hunts (in the 16th century and later) suggest considerable forest cover. Even today, in the Indus Plain not far from the river, there are thorn forests of open acacia and bush and undergrowth of poppies, vetch, thistles, and chickweed. Near the river there are pampalike stretches of tall grass, and streams and canals are often lined with tamarisk trees and some dense scrub. However, nowhere is there a natural forest. Efforts at reforestation in some parts of the Thal area in the Punjab region east of the Indus have been successful. Cultivated areas close to the river have many trees, and the strip below the mountains has something of the appearance of parkland. Coniferous trees abound in the mountainous region along the upper Indus.

The Indus is moderately rich in �sh. The best-known variety is called hilsa and is the most- important edible �sh found in the river. Tatta, Kotri, and Sukkur, all in Sindh province, are important �shing centres. Between the Swat and Hazara areas the river is noted for trout �shing. Fish farming has become important in the reservoirs of dams and barrages. Near the mouth of the Indus—for about 150 miles (240 km) along the coast—there are numerous creeks and areas of shallow seawater. This zone is rich in marine �sh, the most-important catches including pomfrets and prawns, caught from November to March. A modern �sh harbour has been built near the port of Karachi, providing cold storage and marketing. An export trade in prawns has developed, and sea �sh are marketed in different parts of Pakistan.

PEOPLE

Peoples living along the upper reaches of the Indus—e.g., Tibetans, Ladakhi, and Balti—show af�nities with Central rather than South Asia. They speak Tibetan languages and practice Buddhism, although the Balti have adopted Islam. Pastoralism is important in the local economy. In the main Himalayan ranges, areas drained by the

Attock Fort along the Indus River, northern headwaters of the major Indus tributaries form a Punjab province, Pakistan. https://www.britannica.com/print/article/286872 4/9 10/12/2017 Indus River -- Britannica Online Encyclopedia 10/12/2017 Indus River -- Britannica Online Encyclopedia PLANT AND ANIMAL LIFE Robert Harding World Imagery/Getty Images transitional zone where Tibetan cultural features mingle with those of the Indian pahari (hill) region. There is a close relationship between climate and vegetation in the Indus valley. In Sindh Elsewhere in the Indus valley the inhabitants speak Indo-European languages and are province on the lower Indus, desert conditions prevail 10 to 25 miles (15 to 40 km) away from Muslims, re�ecting repeated incursions of peoples entering the Indian subcontinent from the the river, and the area is dominated by sand and poor grass cover. Irrigation by �oods or canals west over several millennia. The rugged mountains of the western Kashmir region are permits some cultivation, although intensive irrigation often produces soil salinization. In inhabited by Dardic-speaking groups (Ka�r, Kohistanis, Shinas, and Kashmiri Gujar), whose northern Sindh and in Punjab province, overgrazing and felling timber for fuel have destroyed languages, like most in the region, are Indo-European in origin. In the Hunza River valley, the much of the natural vegetation. Further, prolonged human interference with natural drainage long-lived Burusho speak a language (Burushaski) that has no known ties to any other and deforestation in the Himalayan foothills have led to a drop in groundwater levels and a language. Those groups combine herding with irrigation-based cultivation. further loss of vegetation. It appears that in prehistoric and earlier historic times the middle Indus region was more wooded than it is at present: accounts of Alexander the Great’s Indian Pashtuns, speaking Pashto and closely related to the tribes of Afghanistan, predominate in campaigns (c. 325 BCE) and records of Mughal hunts (in the 16th century and later) suggest northwestern Pakistan. The Yusufzai are the largest of the Pashtun tribes, others being the considerable forest cover. Even today, in the Indus Plain not far from the river, there are thorn Afridi, Muhmand, Khattak, and Wazir. In the mountainous tribal areas of Pakistan’s Khyber forests of open acacia and bush and undergrowth of poppies, vetch, thistles, and chickweed. Pakhtunkhwa province, the �ercely independent Pashtuns retain their traditional tribal Near the river there are pampalike stretches of tall grass, and streams and canals are often structure and political organization. lined with tamarisk trees and some dense scrub. However, nowhere is there a natural forest. The well-watered northern Indus plains are settled by agricultural groups who speak Punjabi, Efforts at reforestation in some parts of the Thal area in the Punjab region east of the Indus Lahnda, and related dialects and who form the most numerous of the Indus valley peoples. have been successful. Cultivated areas close to the river have many trees, and the strip below Language, ethnicity, and tribal organization play a less-important role in differentiating groups the mountains has something of the appearance of parkland. Coniferous trees abound in the there. The major distinguishing feature among Punjabi peoples is caste, although without the mountainous region along the upper Indus. religious and ritual connotations of the Hindu system. Muslim Jats and Rajputs are important The Indus is moderately rich in �sh. The best-known variety is called hilsa and is the most- Punjabi communities. important edible �sh found in the river. Tatta, Kotri, and Sukkur, all in Sindh province, are The lower Indus valley is inhabited by agricultural peoples who speak Sindhi and related important �shing centres. Between the Swat and Hazara areas the river is noted for trout dialects. Many cultural traits in the region appear to be of considerable antiquity, and the �shing. Fish farming has become important in the reservoirs of dams and barrages. Near the Sindhi pride themselves on their regional distinctiveness. Karachi, though in Sindh, is mouth of the Indus—for about 150 miles (240 km) along the coast—there are numerous creeks predominantly an Urdu-speaking city settled by Punjabis and muhajir, immigrants from India and areas of shallow seawater. This zone is rich in marine �sh, the most-important catches who arrived in Pakistan after partition of the subcontinent in 1947. including pomfrets and prawns, caught from November to March. A modern �sh harbour has been built near the port of Karachi, providing cold storage and marketing. An export trade in ECONOMY prawns has developed, and sea �sh are marketed in different parts of Pakistan. IRRIGATION PEOPLE Irrigation from Indus waters has provided the basis for Peoples living along the upper reaches of the Indus—e.g., successful agriculture since time immemorial. Modern Tibetans, Ladakhi, and Balti—show af�nities with Central irrigation engineering work commenced about 1850, and, rather than South Asia. They speak Tibetan languages and during the period of British administration, large canal practice Buddhism, although the Balti have adopted systems were constructed. In many cases, old canals and Islam. Pastoralism is important in the local economy. In inundation channels in the Sindh and Punjab regions the main Himalayan ranges, areas drained by the Section of the Sukkur Barrage irrigation were revived and modernized. Thus, the greatest system project, on the Indus River, Pakistan. Attock Fort along the Indus River, northern headwaters of the major Indus tributaries form a of canal irrigation in the world was created. At the Punjab province, Pakistan. https://www.britannica.com/print/article/286872 4/9 https://www.britannica.com/print/article/286872 5/9 10/12/2017 Indus River -- Britannica Online Encyclopedia Frederic Ohringer—Nancy Palmer partition of British India in 1947, the international Agency/Encyclopædia Britannica, Inc. boundary between India and what was then West Pakistan cut the irrigation system of the Bari Doab and the Sutlej Valley Project—originally designed as one scheme—into two parts. The headwork fell to India while the canals ran through Pakistan. That led to a disruption in the water supply in some parts of Pakistan. The dispute that thus arose and continued for some years was resolved through the mediation of the World Bank by a treaty between Pakistan and India (1960) known as the Indus Waters Treaty. According to that agreement, the �ow of the three western rivers of the Indus basin—the Indus, Jhelum, and Chenab (except a small quantity used in Jammu and Kashmir state)—is assigned to Pakistan, whereas the �ow of the three eastern rivers—the Ravi, Beas, and Sutlej—is reserved exclusively for India.

In India a number of dams, barrages, and link canals have been built to distribute water from the eastern Indus Irrigated rice fields on the bank of the Indus River in Sindh province, Pakistan. tributaries to the Punjab and neighbouring states. The Harike Barrage, at the con�uence of the Beas and Sutlej, Copyright J.M. Kenoyer/Harappa.com; Courtesy Department of Archaeology and channels water into the Indira Gandhi Canal, which runs Museums, Government of Pakistan for about 400 miles (640 km) to the southwest to irrigate some 1.5 million acres (607,000 hectares) of desert in western Rajasthan. The main canal was completed in 1987.

Following promulgation of the 1960 treaty, the Pakistan Water and Power Development Authority built several linking canals and barrages to divert water from its western rivers to areas in the east lacking water. The biggest of those canals is the Chashma-Jhelum link joining the Indus River with the Jhelum River, with a discharge capacity of some 21,700 cubic feet (615 cubic metres) per second. Water from that canal feeds the Haveli Canal and Trimmu-Sidhnai- Mailsi-Bahawal link canal systems, which provide irrigation to areas in southern Punjab province.

The Indus Waters Treaty also made provision for the construction of two major dams in Pakistan. The Mangla Dam on the Jhelum River near the town of Jhelum is one of the largest rolled earth-�ll dams in the world. It has a crest length of about 10,300 feet (3,140 metres) and a maximum height of more than 480 feet (146 metres)—a �gure that includes the results of a project, completed in 2009, that raised the height of the dam by 30 feet (9 metres). Mangla Reservoir, created by the dam, is 40 miles (64 km) long and has a surface area of 100 square miles (260 square km). The project generates some 1,000 megawatts of hydroelectricity. In https://www.britannica.com/print/article/286872 6/9 10/12/2017 Indus River -- Britannica Online Encyclopedia 10/12/2017 Indus River -- Britannica Online Encyclopedia Frederic Ohringer—Nancy Palmer partition of British India in 1947, the international addition, the reservoir has been developed as a �shing centre and a tourist attraction as well as Agency/Encyclopædia Britannica, Inc. boundary between India and what was then West a health resort. Pakistan cut the irrigation system of the Bari Doab and The second gigantic project is the Tarbela Dam on the Indus, 50 miles (80 km) northwest of the Sutlej Valley Project—originally designed as one Rawalpindi. The dam, of the earth- and rock-�lled type, is 9,000 feet (2,700 metres) long and scheme—into two parts. The headwork fell to India while 470 feet (143 metres) high, and its reservoir is 50 miles (80 km) long. The dam’s generating the canals ran through Pakistan. That led to a disruption capacity is some three times that of the Mangla Dam, and its total potential is considerably in the water supply in some parts of Pakistan. The dispute greater. that thus arose and continued for some years was A third major structure, completed in 2004, is the Ghazi Barotha hydroelectric project, located resolved through the mediation of the World Bank by a below Tarbela. The Indus is partially diverted there to a powerhouse that can generate 1,450 treaty between Pakistan and India (1960) known as the megawatts. Indus Waters Treaty. According to that agreement, the �ow of the three western rivers of the Indus basin—the On the Indus itself there are several important headworks, or barrages, after the river reaches Indus, Jhelum, and Chenab (except a small quantity used the plain. In the mountainous region the principal waterways west of the Indus are the Swat in Jammu and Kashmir state)—is assigned to Pakistan, Canals, which �ow from the Swat River, a tributary of the Kābul River. Those canals provide whereas the �ow of the three eastern rivers—the Ravi, irrigation for the two chief crops of the area, sugarcane and wheat. The Warsak multipurpose Beas, and Sutlej—is reserved exclusively for India. project on the Kābul River, about 12 miles (19 km) northwest of Peshawar, provides irrigation for food crops and fruit orchards in the Peshawar valley and is designed to produce 240,000 In India a number of dams, barrages, and link canals have kilowatts of electricity. In the plains region the Kalabagh, or Jinnah, Barrage controls the been built to distribute water from the eastern Indus Irrigated rice fields on the bank of the Indus system of canals in the Thal Project, organized in 1949. The project, which irrigates a former River in Sindh province, Pakistan. tributaries to the Punjab and neighbouring states. The desert area, is aimed at expanding agriculture, developing rural industry, and promoting the Harike Barrage, at the con�uence of the Beas and Sutlej, Copyright J.M. Kenoyer/Harappa.com; settlement of population in villages and towns. Farther downstream is the Chashma Barrage. Courtesy Department of Archaeology and channels water into the Indira Gandhi Canal, which runs Still farther the Taunsa Barrage, designed for the irrigation of land in the Dera Ghazi Khan and Museums, Government of Pakistan for about 400 miles (640 km) to the southwest to irrigate Muzaffargarh districts, also produces about 100,000 kilowatts of electricity. Within the Sindh some 1.5 million acres (607,000 hectares) of desert in there are three major barrages on the Indus—Guddu, Sukkur, and Kotri, or Ghulam western Rajasthan. The main canal was completed in 1987. Muhammad. The Guddu Barrage is just inside the Sindh border and is some 4,450 feet (1,356 Following promulgation of the 1960 treaty, the Pakistan Water and Power Development metres) long; it irrigates cultivated land in the region of Sukkur, Jacobabad, and parts of Authority built several linking canals and barrages to divert water from its western rivers to Larkana and Kalat districts. The project has greatly increased the cultivation of rice, but cotton areas in the east lacking water. The biggest of those canals is the Chashma-Jhelum link joining also has become a major crop on the left bank of the river and has replaced rice as a cash crop. the Indus River with the Jhelum River, with a discharge capacity of some 21,700 cubic feet (615 The Sukkur Barrage was built in 1932 and is about 1 mile (1.6 km) long. The canals originating cubic metres) per second. Water from that canal feeds the Haveli Canal and Trimmu-Sidhnai- from it serve a cultivable area of about 5 million acres (2 million hectares) of land producing Mailsi-Bahawal link canal systems, which provide irrigation to areas in southern Punjab both food and cash crops. The Kotri Barrage, also known as the Ghulam Muhammad Barrage, province. was opened in 1955. It is near Hyderabad and is nearly 3,000 feet (900 metres) long. The right- The Indus Waters Treaty also made provision for the construction of two major dams in bank canal provides additional water to the city of Karachi. Sugarcane cultivation has been Pakistan. The Mangla Dam on the Jhelum River near the town of Jhelum is one of the largest expanded, and yields of rice and wheat have increased. rolled earth-�ll dams in the world. It has a crest length of about 10,300 feet (3,140 metres) and Experience in the Indian subcontinent and elsewhere has shown that canal irrigation, unless a maximum height of more than 480 feet (146 metres)—a �gure that includes the results of a carefully controlled, can seriously damage cultivated land. The water in unlined canals seeps project, completed in 2009, that raised the height of the dam by 30 feet (9 metres). Mangla through the soil and raises the water table, so the soil becomes waterlogged and useless for Reservoir, created by the dam, is 40 miles (64 km) long and has a surface area of 100 square cultivation. As irrigation by canals has expanded along the Indus and its tributaries, in some miles (260 square km). The project generates some 1,000 megawatts of hydroelectricity. In https://www.britannica.com/print/article/286872 6/9 https://www.britannica.com/print/article/286872 7/9 10/12/2017 Indus River -- Britannica Online Encyclopedia areas groundwater has risen above the surface to form shallow lakes. Elsewhere the water has evaporated in the intense summer heat, leaving behind layers of salt that make crop production impossible. Steps have been taken to provide adequate drainage systems to avoid waterlogging and salt buildup.

NAVIGATION

Until about 1880 the Indus and the other Punjab rivers carried some navigation, but the advent of the railways and expansion of irrigation works have eliminated all but small craft that ply the lower Indus in Sindh. There are �shing boats on the lower Indus, and the upper reaches of rivers and canals above the �rst railway crossing are now used for �oating timber down from the foothills of the Kashmir region.

Na�s Ahmad

Deryck O. Lodrick

The Editors of Encyclopædia Britannica

Source: "Indus River". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2017. Web. 12 Oct. 2017 .

https://www.britannica.com/print/article/286872 8/9 10/12/2017 Indus River -- Britannica Online Encyclopedia 10/12/2017 Indus River -- Britannica Online Encyclopedia areas groundwater has risen above the surface to form shallow lakes. Elsewhere the water has evaporated in the intense summer heat, leaving behind layers of salt that make crop production impossible. Steps have been taken to provide adequate drainage systems to avoid waterlogging and salt buildup.

NAVIGATION

Na�s Ahmad

Deryck O. Lodrick

The Editors of Encyclopædia Britannica

"Indus River". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2017. Web. 12 Oct. 2017 .

https://www.britannica.com/print/article/286872 8/9 https://www.britannica.com/print/article/286872 9/9