Over the next decade, more than 400 large dams will be built on the Himalayan rivers—by India, China, Nepal, Bhutan, and Pakistan—to feed the region’s hunger for electricity and its need for irrigation. New ports and thermal power plants line the coastal arc that runs from India, through Southeast Asia, to China. India and China have embarked on schemes to divert rivers to bring water to their driest lands: Costing tens or hundreds of billions of dollars, they are the largest and most expensive construction projects the world has ever seen. At stake in how these plans unfold is the welfare of a significant portion of humanity. At stake is the future shape of Asia, the relations among its nations.
The Indian subcontinent is the crucible of the monsoon. In its simplest definition, the monsoon is “a seasonal prevailing wind.” There are other monsoons, in northern Australia and in North America; none is as pronounced, as marked in its reversal between wet and dry seasons, as the South Asian monsoon. More than 70 percent of total rainfall in South Asia occurs during just three months each year, between June and September. Even within that period, rainfall is not consistent: It is compressed into just 100 hours of torrential rain across the summer months.
Despite a vast expansion in irrigation since 1947, 60 percent of Indian agriculture remains rain-fed, and agriculture employs about half of India’s population. Unlike China, unlike most large countries in the world, India’s population will continue to be predominantly rural until the mid-21st century. No comparably large number of human beings anywhere in the world is so dependent on such intensely seasonal rainfall. In the first decade of the 20th century, the finance minister in the imperial government declared that “every budget is a gamble on the rains”; more than a century later, the leading environmental activist Sunita Narain reversed the terms but retained the substance of the observation: “India’s finance minister is the monsoon,” she declared.