ELOPA, Arunachal Pradesh — Amid a desert of volleyball-sized boulders, Jibi Pulu bounces his Tata jeep over a trickling nullah. In his childhood, just 30-odd years ago, this stream used to irrigate his family paddy fields right here in the flatlands and provide fresh water to his ancestral village in the hills above the floodplain of the Dibang River, a major tributary of the Brahmaputra.
Today, the paddy fields are gone, and the village is abandoned, fallen prey to hillside erosion and river siltation. “This plain was once a narrow band of huge trees,” said Mr. Pulu, who heads the Idu-Mishmi tribe’s Community Resource Management Committee. “Now it’s a stony wasteland stretching for farther than the eye can see.
“As a young boy, I could sit here and watch animals come down right there to the river to drink – sambar deer, barking deer, wild boars, tigers, leopards, herds of wild elephants. It was like an African safari park. Now all you see of the animals are occasional tracks and droppings.”
Experiences like Mr. Pulu’s give vivid life to the numeric inputs that fuel Professor Subashisa Dutta’s statistical models. Together with his fellow civil engineering professor Shyamal Ghosh at the Indian Institute of Technology in Guwahati, Mr. Dutta has published the most recent climate change models of the Brahmaputra River basin. Using the known flood characteristics of the basin, they plugged in regional rainfall projections under the climate change scenario that assumes warming over the Indian subcontinent because of greenhouse gas concentrations.
The results look grim. The Brahmaputra valley will experience “longer floods and more flood events outside the monsoon period,” Mr. Dutta predicted. Not only will peak flows increase, but so will the incidence of pre-monsoon floods, which could jeopardize key production phases in the agricultural cycle.
The worst threat, he added, will not come from cataclysmic once-in-a century floods, but rather from increasing year-to-year volatility. “Five-year-period floods will have more change than the 50-year-period floods,” Mr. Dutta said. And some of the biggest impacts will happen at the tributary level, rather than on the main channel of the Brahmaputra.
“Many tributaries on the North Bank are changing course or transforming from a meandering river to a braided river,” he said. This can only make the floods “flashier, drastically changing the hazards,” he warned.
Right across the Indian Institute of Technology’s expansive academic complex, Arupjyoti Saikia, a historian, has reached much the same conclusion from a far more anecdotal, almost personalized approach. Freshly returned from a fellowship at Yale University’s Agrarian Studies program, Mr. Saikia is now writing a kind of biography of the Brahmaputra.
It’s a short biography, in geologic terms. If the Brahmaputra were a person, it would be a tempestuous teenager who frequents all-night raves during the wet season. Its youthful temperament reflects the young geology of its Himalayan catchment basin as much as the heavy monsoon rainfall it receives.
Viewed on the human time scale, on the other hand, the Brahmaputra presents an immemorial landscape that is in peril. Though the plains in Assam have been settled for thousands of years, Mr. Saikia noted that only in the last hundred have people lived so close to the river.
Population pressure on the land, he explained, has pushed people to migrate into areas vulnerable to flood. In the past, those who cultivated in the flood plains always migrated to higher land during flood season. But nowadays, Assam is much too crowded for people to make these seasonal migration shifts.
To screen the encroaching population from river hazards, the government of India went on a misguided embankment-building spree between the late 1940s through the 1970s.
People believed – and still do – that the embankments would protect them against floods. But time and again, that hope has proved false. Just this past flood season over 60 embankments broke, sending surging water into thatched-roof villages.
For at least four decades it has been clear to the technocrats that embankments spelled trouble, only compounding the hazards of the river while failing to tame it. But by the 1970s, “it was already too late; there was no going back,” Mr. Saikia lamented. “It permanently jeopardized the rhythm of the water.”
Yet “the Brahmaputra is still free,” Mr. Saikia said, sighing. Come monsoon time, “it can still play with its rhythm and it can dance as it likes.”
Jibi Pulu, who remembers the flowing waters that fed the rice paddy of his youth, knows this firsthand in his home region of the Dibang basin.
“See that plinth over there,” he said, pointing to a crumbling block of concrete atop an undercut bank. “Some Hindus tried to tame the river by building a Shiva temple there.” But just last year, the Dibang danced right over Nataraja, the lord of the cosmic dance.
Brian Orland’s dispatches will appear regularly in India Ink. Last month, he wrote about population growth along the Brahmaputra.
India Ink: A Volatile Brahmaputra River Will Grow Only More So
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