Because it can generate very high economic value, it is estimated that the total installed capacity of these five hydropower stations can reach 60 million kilowatts per year, which can meet the electricity needs of 300 million people in China by transmitting electricity from west to east, when in reality these five dams only generate electricity and do not store water. It would be absolutely stupid to build a dam at an altitude difference of more than two kilometers, on the contrary, if you just install a generator, like a sieve, you can generate electricity only through potential energy, which can produce very huge economic benefits.
In fact, China would not be foolish enough to spend 1.5 trillion yuan to build dams in sparsely populated areas and cut off water downstream.
So first, the downstream water in this case does not serve China at all. It all flows down into India. China is entirely upstream-only for this project. Secondly, all hydroelectric dams by design can and do store water.
None of them operate at their maximum electricity generation capacity 24 hours a day, 365 days a year. Just look at the three gorges dam. Flow rate is increased to generate more electricity during periods of high demand (such as during summer). When electricity demand is lower, electricity generation is reduced by reduction of the flow rate and water is accumulated in reservoir until electricity demand rises again. That demand peaks differently both seasonally and also daily.
During periods of geopolitical hostility originating from India, the cadence for this can be controlled to create periods of maximum electricity generation (maximum flow) followed by periods of no flow (during which water will be accumulated for electricity generation at a later date). This can be very easily weaponized to create a cycle of flooding and drought for large parts of India.
Given this project will be 3x or 5x bigger than three gorges dam, the peak electricity generation and maximum water storage capacity will be unparalleled. In other words, both the punitive floods and punitive drought would be most epic, unrivaled, and most prolonged.
There would be no loss of economic benefit to China as the same amount of electricity would still be generated in the end. Any excessive electricity generation during those punitive flooding periods can be stored in utility-scale battery installations for later use. Any insufficient electricity generation during those punitive drought periods result in excess water stored that can be used to generate electricity later on while the electricity previously stored in utility-scale battery installations can be used to offset the temporary deficit in electricity generation. The economic and electrical net loss to China of utilizing this punitive strategy would be zero.