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Global 200 > Large River Deltas >
Indus River Delta (156)

Indus River Delta
Indus Delta, Pakistan
Photograph by Tariq Mahmood


Western part of the Indian subcontinent: Pakistan
Large River Deltas

About 16,000 square miles (40,000 square kilometers) -- about twice the size of Massachusetts


· Where Snow Turns to Swamp
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
· Looking Ahead

Global 200 Snapshot

The Indus River Delta is a highly productive ecoregion at the juncture of both freshwater and marine systems. It has a rich freshwater fauna and is an important area for migrating water birds.  

Where Snow Turns to Swamp

Melting snow and glacier ice in the Himalayan Mountains pour into the Indus River, which picks up speed as it heads through Pakistan. Throughout its 1,900 mile (3,000 km) course, the Indus provides mineral-rich soil and water to its floodplains. Both the Indus and the streams that feed it are home to many types of unusual fish and other animals.

Special Features Special Features

Heavy rains swell the Indus River during the monsoon season from June to September. Because this happens soon after the winter snows melt, floods can occur at this time of year. For a long distance, the river is a wide channel of cloudy water twisting through a dry landscape. Before it pours into the Arabian Sea, the Indus creates a wide delta of swamps, streams, and extensive mangroves.

Did You Know?
After thousands of years of living in cloudy water, the Indus River dolphin has nearly lost its eyesight because it no longer needs it. Instead it has evolved a special ability called "echolocation" for hunting and navigation. The dolphin swims on its side and detects prey and other objects through sound waves.

Wild Side

Many fish species live in or migrate through the waters of the Indus River Delta. The Hilsa shad swims up from the Arabian Sea to spawn in freshwater. This fast swimmer has been clocked at 43 miles (71 km) per day. Other unusual fish that live in the Indus include the Indus baril, Indus garua (a catfish), and the Rita catfish. Several snakehead fish also live here, including the giant snakehead, which can grow to be 6 feet (2 m) long and eats fish, frogs, snakes, insects, and earthworms. There are even reports that it will occasionally eat a water bird! Species that are important to people as food, such as the golden mahaseer and large freshwater shrimp, are part of the abundant aquatic life of the delta. But the most unusual member of the ecoregion is the endangered Indus River dolphin, one of four species of freshwater dolphin in the world.

Cause for Concern

Dams on the river reduce flows in lower portions of the system and limit the transport of fertile sediments downstream into the delta. They pose a serious threat to the survival of the Indus River dolphin, as the remaining individuals become isolated into smaller groups. Water extraction for irrigation and run-off of chemicals into the rivers also threaten the freshwater species of the Indus Delta. Introduced species may pose a problem for the native fauna, too.

Looking Ahead

The Pakistani government has established a dolphin reserve along the Indus River and has launched a campaign to eliminate the hunting of dolphins, with the hope of saving this endangered species.

All text by World Wildlife Fund © 2001