By Emran Hossain
Plans by China and India to construct hydropower dams on a major Himalayan river raise the prospect of deadly environmental and humanitarian catastrophes for millions of people living downstream, including those in impoverished Bangladesh.
Low-lying, largely agricultural Bangladesh is already feeling the brunt of a worsening crisis fueled by dams on transboundary rivers in upstream India. It has caused the drying up of rivers, dwindling crop production, and loss of livelihood for hundreds of thousands of farmers, pushing millions into poverty.
Scientific studies reveal that water diversion in India over the decades choked important rivers, including the Ganges, which takes the name Padma in Bangladesh, and the Teesta, a major tributary of the Brahmaputra River.
India and China are currently competing to build two of the world’s largest hydroelectric projects on the Brahmaputra’s main course, with water diversion plans threatening to drastically reduce the flow, particularly during the lean season.
Experts have described the latest plans to dam the Brahmaputra as reckless, particularly given the reality of climate change, where glacial lakes frequently burst and flash floods are triggered by heavy rains or cloud bursts.
Bangladesh faces a particularly serious challenge, as a reduction in the flow of fresh river water means saltwater intrusion, a phenomenon observed in parts of the southern coastal region.
Mega dams, mega threats
China is building a 60-gigawatt hydroelectric power facility in Medog, Tibet. It is considered the world’s largest hydroelectric power facility, with a capacity twice that of Bangladesh’s current generation capacity.
The US$170 billion project requires diverting 70 percent of the Brahmaputra’s natural flow. Called the Yarlung Zanbo in China, the Brahmaputra is 2,900 kilometers long and has a catchment area of 583,000 square kilometers, about four times the size of Bangladesh, before flowing into the Bay of Bengal.
China aims to capitalize on the enormous hydropower potential of a 2,000-meter drop over a distance of 50 kilometers by building a cascade of five stations that will require a tunnel through the Namcha Barwa mountain, which has an elevation of 7,782 meters, to divert the water flow.
Medog Dam, on the border between India and Tibet, is likely to dwarf the giant Three Gorges Dam. Currently billed as the world’s biggest, the Three Gorges displaced 1.4 million people.
Downstream from Medog, India is planning to build a US$17 billion dam in Arunachal Pradesh, the Brahmaputra’s entry point into India. With an estimated generation capacity of 11 gigawatts, the dam will store 9.3 billion cubic meters of water, enough to sustain 170 million people for one year.
Brahmaputra, the indispensable river
The Brahmaputra is the source of 70 percent of Bangladesh’s current natural fresh water supply. The river is an indispensable part of the Ganges-Brahmaputra-Meghna delta, also known as the Bengal delta, which was formed over centuries as the three river systems carried sediment downstream from the Himalayas to merge with the Bay of Bengal.
The sediment load in the joint river systems has halved to 1 billion tons from 2 billion tons over the past six decades, primarily attributed to dams and barrages trapping sediment upstream.
The Brahmaputra catchment area in India is particularly prone to rainfall. Damming the river means messing with an area responsible for draining one of the world’s wettest places.
India’s withholding of the Brahmaputra’s water will likely lead to a further increase in groundwater extraction for irrigation in Bangladesh, where groundwater levels have drastically declined over the last few decades, particularly in the catchment areas of the Ganges and Teesta, where natural water flow has drastically dropped due to barrages.
The Brahmaputra contributes substantially to the flow of the Meghna River, which keeps the rising sea at bay.
Silence while millions suffer
Besides trapping sediment, dams can lead to riverbed degradation, loss of soil fertility, and reduced water quality in downstream countries. Less natural water availability for irrigation results in excessive agricultural expenses, which are difficult to recover because crop failure becomes frequent due to flash floods, heat stress, and untimely rains.
A 2023 study revealed that the water flow in the Padma River had decreased by 26 percent over the last four decades, while the river’s flow during the lean season shrank by 50 percent.
It also stated that the permanent water area decreased from 140 square kilometers in 1984 to 70 square kilometers in 2019. The river’s depth also decreased from 12.8 meters in 1985 to 11.1 meters in 2019. One-third of the native fish species available in the Padma in 1982 have disappeared.
The Teesta, once a mighty river, has become a stream in Bangladesh, often broken by vast stretches of sandy riverbeds, because India arbitrarily withdrew almost the entire river flow at the Gajaldoba Barrage, built in 1995.
India also built dams on the tributaries of the Teesta, constructed reservoirs, and diverted an estimated 10 percent of water from the Teesta to the Mahananda, according to Indian media reports.
A study in 2016 revealed that water scarcity in the Teesta has caused the loss of 4.45 million metric tons of rice in the Nilphamari, Sayedpur, and Rangpur regions of Bangladesh in the last ten years.
Millions are already suffering due to the blocking of natural water flows in impoverished regions in South Asia and beyond. The new dams on the Brahmaputra are extremely bad news for many more millions in Bangladesh.
Sadly, the international community is largely silent on this issue, which is likely to become a nightmare for innocent millions, many of whom will be pushed to face poverty, displacement, and even death in the coming years.
The article was published in the ucanews