Indus River

Category: Inland Aquatic Biomes.

Geographic Location: Asia.

Summary: The backbone of agriculture and food production in Pakistan, the Indus River biome has been damaged by human activity; its future is jeopardized by global warming.

The Indus River is one of the major rivers of south Asia. Its name derives from the Sanskrit word Sindhu, which simply means river or ocean. The Indus basin largely depends on the snows and glaciers of several key mountain ranges: the Himalayan, Karakoram, and Hindu Kush ranges of Tibet, northern Pakistan, and Afghanistan. The river originates near Mount Kailash on the Tibetan Plateau and travels southwestward approximately 1,900 miles (3,050 kilometers) before draining into the Arabian Sea, a northern part of the Indian Ocean.

Geography and Hydrology

The annual flow of the Indus is 7.3 trillion cubic feet (207 billion cubic meters)—twice the volume of the Nile River. The Tibetan Plateau ice field contains the largest area under perennial snow outside of the polar regions. Here, the Indus River headwaters are found, at an elevation of about 18,000 feet (5,500 meters). The glacial melt flows into the territory of Kashmir in India before entering Pakistan. Then it runs along the slopes of the Karakoram Range and the Nanga Pabat massif, forming gorges that reach depths of 15,000–17,000 feet (4,600–5,200 meters).

The river continues as a mountain river in Pakistan’s North West Frontier Province, before reaching the Punjab Plain. (The word Punjab means water of five rivers.) There, it receives five important tributaries—Jhelum, Chenab, Ravi, Beas, and Sutlej—that make it much larger, often resulting in flooding during the monsoon season. Another tributary of significance is the Kabul River, which rises in Afghanistan, crosses the Afghan-Pakistan border near the Khyber Pass, and flows into the main branch of the Indus at Attack, above the confluences of the five tributaries.

The Indus River basin covers about 200,000 square miles (518,000 square kilometers), extending from the foothills of the Himalayas to the Arabian Sea. Flooding during the rainy season is very common in the region; much of the ecosystem richness along the river is sustained by these regular flooding episodes. However, in 2010, extreme flooding in the basin and adjacent areas affected more than 20 million people and deluged nearly one-fifth of Pakistan. The 2010 flood was determined to be the most destructive in the history of Pakistan. Flooding also occurred in 2012, 2015, and 2016 although not as severe. Severe flooding also occurred in Pakistan in 2022, though unlike the 2010 flood it was not a direct result of the Indus River flooding. However, heavy monsoon rains during that time combined with peak flow rate of the Indus to create a deadly situation.

Biota

The Indus River basin covers a wide range of ecosystems, from the Tibetan Plateau alpine steppe through scrubland, the Indus Valley Desert, xeric woodlands, and broadleaf forests, to subtropical pine forests and the Indus Valley mangroves. Near the foothills, the dominant tree species is the deodar cedar (Cedrus deodara). In the plains, the most common tree species are acacia (Acacia arabica), shisham (Dalbergia sissoo), thistles, and tamarisk or salt cedar. Several palm species are found in the delta region.

The Indus River, including the delta region, is rich in fish species. There are 22 endemic (found nowhere else on Earth) fish species among the approximately 150 fish species that have been identified here. The endemics include Indus baril (Barilius modestus), Indus garua (Clupisoma naziri), and Rita catfish (Rita rita). The most common, and one of the commercially valuable, species found in the river is the Hilsa (Tenualosa ilisha), a local favorite edible species. Other common fish here are the palla, sukkur, thatta, and kotri, and several varieties of both catfish and snakehead.

An endangered dolphin species, the Indus River dolphin (Platanista minor), is endemic to the Indus River. In recent years, this cetacean has been threatened, due to its small population size, fragmentation of the river by dams and barrages, catching and poaching, pollution, and habitat degradation. World Wildlife Fund has been working in collaboration with Sindh Wildlife Department to educate fisherman and promote activities to help save this species.

The delta region is rich in marine life, and is considered to be one of the most important ecological regions in the world. The Indus River Delta–Arabian Sea mangroves support a high-salinity estuary, due to the salts brought to the coast by the Indus from the desert, a process that has intensified as the river is increasingly used for irrigation and water supply. Mangroves are an important habitat that support a range of plants specialized to survive in this salty environment. The mangroves here also support large numbers of fish, crustaceans such as freshwater shrimp, and invertebrates that find food, shelter and oxygen in the waters beneath the tree roots. Mangroves are also home to about 25 amphibian species and large numbers of migratory seabirds.

Human Impact

The Indus River has influenced the history, culture, geography, and economy of the region for thousands of years. Historically, the Indus Valley is known as one of the earliest hubs of human civilizations. The ancient cities of Harappa and Mohenjo-Daro, dating back to at least 3300 B.C.E., were discovered here.

There is evidence that ancient civilizations constructed an extensive network of irrigation canals in the region. The British East India Company initiated modern irrigation in 1851, with two major systems, the Guddu Barrage and Sukkur Barrage. The partition of India and Pakistan in 1949 led to the signing of the Indus Waters Treaty in 1960, which guarantees Pakistan water from the Indus, Jhelum, and Chenab Rivers, and gives India the rights to the water of the Ravi, Beas, and Sutlej Rivers. The treaty also permitted the construction of two huge dams in Pakistan. Overall, there are three major dams, 23 barrages, 12 inter-river canals, 48 canals, and 106,000 watercourses in the Indus River basin to either generate power or to irrigate. Unfortunately, many of these constructions have degraded the immediate and extended habitats around the Indus.

Pakistan depends on the Indus, especially because the lower plains and arid lands receive little rainfall. In recent years, the Indus River and the surrounding area have been affected by extensive deforestation, industrialization, urbanization, and climate change. Because of deforestation, the river is even shifting its course westward. Industrialization and urbanization have polluted the waters, affecting aquatic life.

Extensive construction of dams and barrages has altered the volume and flow of the river in the delta. This alteration of water flow is having a direct effect on the natural ecosystem and the lives of people in the region. The effect of climate change on the glacial and snow mountains of the Himalayas will further affect the flow of water in the river, and will have a huge effect on the people living in the lowlands.

Experts predict an increased temperature, shifting precipitation, and changes in the timing of snowfall and glacier melt in the coming decades. However, there will be additional pressure, as the population of Pakistan has significantly expanded in recent decades, to nearly 190 million, while that of India has reached 1.2 billion people. Feeding this number of people, many of whom live in semiarid environments, will pose a great challenge and will further stress their main water sources.

Adding to the tension, parts of the Indus River and several of its major tributaries flow through India, with whom Pakistan has had a long-standing border dispute in the Kashmir region. The two countries have fought two wars over the issue; despite the 1960 treaty, Pakistan fears that India might divert water from the upper reaches of the Indus.

Pakistan requires an integrated water-management policy to manage the river, both to meet its people’s demands and to support plant and animal life in the plains. Some options include increasing water storage by improving infrastructure, improving agricultural production by growing more food with less water, preventing increased salinity in the basin and delta, and developing better conservation standards with farmers, municipal managers, and ecologists.

Bibliography

Albinia, Alicia. Empires of the Indus: The Story of a River. W. W. Norton and Co., 2008.

Archer, D. R., et al. “Sustainability of Water Resources Management in the Indus Basin under Changing Climatic and Socio-Economic Conditions.” Hydrology and Earth System Sciences Discussions, vol. 7, no. 1, 2010.

Atif, Salmon, et al. "Investigating the Flood Damages in Lower Indus Basin Since 2000: Spatiotemporal Analyses of the Major Flood Events." Natural Hazards, vol. 108, no. 3, Sept. 2021, link.springer.com/article/10.1007/s11069-021-04783-w. Accessed 25 Sep. 2024.

Michel, Aloys Arthur. The Indus Rivers. Yale UP, 1967.

Nanditha, J.S., et al. “The Pakistan Flood of August 2022: Causes and Implications.” Earth’s Future, vol. 11, no. 3, 13 Mar. 2023, agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022EF003230. Accessed 25 Sep. 2024.

Qureshhi, Asad Sarwar. “Water Management in the Indus Basin in Pakistan: Challenges and Opportunities.” Mountain Research and Development, vol. 31, no. 3, 2011.

Revees, Randall R., and Abdul Aleem Chaudhry. “Status of the Indus River Dolphin Platanista Minor.” Oryx, vol. 32, no. 1, 1998.