Physical features

The Indus River is about 1,800 miles (2,900 kilometers) long. It starts high in the Himalayas in the Tibet region of China. For about 500 miles (800 kilometers) the Indus flows swiftly through some of the world's tallest mountains, in the Himalayas and the nearby Karakoram Range. This course takes the river through northwestern India, the territory of Kashmir, and northern Pakistan. Much of the river's water comes from the melting of glaciers and snow in the mountains.

After leaving the mountains, the Indus flows onto the plains of Pakistan. First it crosses the hot, dry plain of the Punjab region. The name Punjab means “land of the five rivers.” It refers to the five rivers that empty into the Indus there: the Jhelum, Chenab, Ravi, Beas, and Sutlej. The waters of these rivers make the Indus much larger. The Indus then crosses the Sindh plain of southern Pakistan. In the delta region, the Indus breaks into a series of streams that empty into the Arabian Sea.

The amount of water carried by the Indus River depends on the weather. The water level is greatest from July to September, when heavy rains occur and snow melts in the mountains. The Indus sometimes floods during this time. The water level is lowest in the cooler winter months, from December to February.

Plants and animals

In ancient times parts of the Indus plains had a lot of forests. Over the years, however, people have cut down many of the trees to get wood to burn for fuel and to make room for raising livestock. Today there are some forests of acacia trees not far from the river as well as stretches of tall grass along the riverbanks. The Sindh plains in the south are mostly desert, with sand and only a little grass. The swampy delta has forests of mangrove trees.

The Indus is fairly rich in fish. The best-known kind that people eat is called the hilsa. The shallow area at the mouth of the river—that is, where the river empties into the sea—has a lot of shrimp.

In the Indus delta, both plants and animals have suffered in recent years because they have not gotten enough freshwater. The reason for this is the building of dams upstream. The dams store much of the river's water and therefore reduce its flow. By the time the Indus reaches the delta, the water level is much lower than it is upstream. Many of the streams in the delta have dried up altogether. As a result, salt water from the Arabian Sea has flowed into areas that once had freshwater. The salt water has greatly reduced the amount of land covered by mangrove trees. And because the mangrove swamps are important for the reproduction of fish and shrimp, the number of these creatures has dropped as well. Some kinds of fish have almost disappeared.

Economy

The Indus River is very important to the economy of the region through which it flows. Although much of the land is very dry, farming is possible because of the artificial watering methods called irrigation. Since ancient times people have used water from the Indus to water their crops. In the mid–19th century, when the British ruled what is now India and Pakistan, modern canals were built to irrigate the land. After India and Pakistan became independent countries in 1947, arguments arose over who would get to use the waters of the Indus River and its tributaries (the smaller rivers that flow into it). In 1960 the two countries signed a treaty in which they agreed to share the waters of the rivers. The main crops grown in the region are sugarcane, wheat, rice, and cotton.

Dams on the Indus and its tributaries are used both for irrigation and for creating electricity. Irrigation dams store the water that is delivered to the fields by canals. Dams that use the flow of the river to make electricity are called hydroelectric dams. The most important storage and hydroelectric dams are the Mangla Dam on the Jhelum River and the Tarbela Dam on the Indus. Both are in Pakistan.

Environmental issues

Use of the Indus has caused disputes among the people of Pakistan. People who live near the mouth of river believe that they are suffering because of the dams and canals upstream. As the Indus has dried up at its mouth and salt water from the Arabian Sea has flowed in, people have faced shortages of freshwater and flooding of their land. Many people have had to abandon their homes and move to other areas. Some scientists in the region argue that more water should be released from the dams to help push the seawater out. They also believe that any new dams or canals should be built only if they do not have a negative effect on the people living downstream.